To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the...To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the alloy across different planes were investigated.The anisotropy of SLM-fabricated Ti-6Al-4V alloys was analyzed,and the electron backscatter diffraction technique was used to investigate the influence of different grain types and orientations on the stress-strain distribution at various scales.Results reveal that in room-temperature compression tests at a strain rate of 10^(-3) s^(-1),both the compressive yield strength and microhardness vary along the deposition direction,indicating a certain degree of mechanical property anisotropy.The alloy exhibits a columnar microstructure;along the deposition direction,the grains appear equiaxed,and they have internal hexagonal close-packed(hcp)α/α'martensitic structure.α'phase has a preferential orientation approximately along the<0001>direction.Anisotropy arises from the high aspect ratio of columnar grains,along with the weak texture of the microstructure and low symmetry of the hcp crystal structure.展开更多
Chiral magnets have attracted considerable attention due to their intricate magnetic properties,among which B20compounds constitute a quintessential class that has gained significant focus,particularly in the study of...Chiral magnets have attracted considerable attention due to their intricate magnetic properties,among which B20compounds constitute a quintessential class that has gained significant focus,particularly in the study of skyrmions.MnGe,as a member of the B20 family,exhibits a more complex magnetic structure compared with other materials with similar crystal structures.In this work,we successfully synthesized high-quality MnGe thin films and characterized their magnetoresistance,M-H curves,magneto-Seebeck effect,and magnetic force microscopy(MFM)images,all of which demonstrate pronounced magnetic anisotropy.Notably,the Seebeck coefficient exhibits a plateau at low magnetic fields when the magnetic field is applied in the film plane,indicating a field region in which the magnetic structure remains stable.MFM imaging further reveals magnetic transitions within the MnGe films when the magnetic field is oriented along the film plane.These findings are crucial for advancing our understanding of the magnetic ground state of MnGe and the evolution of its magnetic structure under an applied external magnetic field.展开更多
We report the development of the[Pt_(0.75)Ti_(0.25)/Co-Ni multilayer/Ta]_n superlattice with strong spin-orbit torque,large perpendicular magnetic anisotropy,and remarkably low switching current density.We demonstrate...We report the development of the[Pt_(0.75)Ti_(0.25)/Co-Ni multilayer/Ta]_n superlattice with strong spin-orbit torque,large perpendicular magnetic anisotropy,and remarkably low switching current density.We demonstrate that the efficiency of the spin-orbit torque increases nearly linearly with the repetition number n,which is in excellent agreement with the spin Hall effect of the Pt_(0.75)Ti_(0.25)being essentially the only source of the observed spin-orbit torque.The perpendicular magnetic anisotropy field is also substantially enhanced by more than a factor of 2 as n increases from 1 to6.The[Pt_(0.75)Ti_(0.25)/Co-Ni multilayers/Ta]_n superlattice additionally exhibits deterministic,low-current-density magnetization switching despite the very large total layer thicknesses.The unique combination of strong spin-orbit torque,robust perpendicular magnetic anisotropy,low-current-density switching,and excellent high thermal stability makes the[Pt_(0.75)Ti_(0.25)/Co-Ni multilayer/Ta]_n superlattice a highly compelling material candidate for ultrafast,energy-efficient,and long-data-retention spintronic technologies.展开更多
Conventional cross rolling is influenced by the force couple effect of symmetrical rollers,resulting in the c-axis of the plate grains being oriented perpendicular to the rolling surface.This orientation contributes t...Conventional cross rolling is influenced by the force couple effect of symmetrical rollers,resulting in the c-axis of the plate grains being oriented perpendicular to the rolling surface.This orientation contributes to a high degree of work hardening and mechanical anisotropy,thereby complicating subsequent processing.In this study,the hard plate cross rolling(HP-CR)process is put forward for the first time,and the microstructure evolution and mechanical properties of rolled AZ31 Magnesium plate were analyzed.The results indicate that,in comparison to traditional cross rolling(CR),the average grain size of the HP-CR is refined to 5.33µm.Additionally,the average yield strength and elongation of the sheet are enhanced by 15.2%and 35.2%,respectively,while the average tensile strength is 283 MPa,and the r value decreases by 39.8%.These changes are attributed to the combined effects of grain refinement,microstructural homogenization,and basal texture weakening.On the one hand,the substantial energy stored in the original lattice distortion serves as a driving force for the dynamic recrystallization process,facilitating the elimination of the deformed grain structure.This process increases the proportion of recrystallized grains from 5%to 82%,reduces the degree of work hardening,and correspondingly decreases the density of geometrically necessary dislocations(ρ^(GND))by 70.8%,accompanied by the formation of high-angle grain boundaries(HAGB).On the other hand,dynamic recrystallization promotes grain rearrangement,resulting in an increased number of grains oriented in the transverse direction(TD),which diminishes the texture strength of the basal plane.Concurrently,the activation of non-basal slip systems reduces the resistance to dislocation sliding in various directions,significantly reduces the degree of mechanical anisotropy and enhancing the plastic deformation capacity of the plate.This research provides valuable scientific insights and technical foundations for the large-scale manufacturing of high-performance AZ31 magnesium alloy sheets.展开更多
The prevalence of wide-bandgap semiconductors urges the development of advanced soft magnetic materials for high-frequency applications.While soft magnetic alloys are limited by resonances at elevated frequencies,the ...The prevalence of wide-bandgap semiconductors urges the development of advanced soft magnetic materials for high-frequency applications.While soft magnetic alloys are limited by resonances at elevated frequencies,the incorporation of planar anisotropy serves as an effective strategy to overcome this dilemma and extend their potential for high-frequency applications.Herein,nanocrystalline Y_(2)Co_(14)B alloys have been designed with tuned magnetocrystalline and shape bi-anisotropy via melt spinning and magnetic field-assisted annealing.With the application of zero,transverse,rotational and longitudinal magnetic fields(denoted as ZFA,TFA,RFA and LFA),the effects of field direction and annealing time on microstructural and performance evolution have been investigated.Compared with ZFA,magnetic field-assisted annealing not only promotes the growth of nanograins but also alters the coincidence degree between intrinsic easy-plane(IEP)and artificial easy-plane(AEP)structures.While the random distribution of IEP structure is achieved for the RFA due to the formation of non-orientated nanograins,directional magnetic field-assisted annealing contributes to preferentially orientated(006)nanograins,especially for the LFA,resulting in optimal coincidence between the magnetocrystalline anisotropy and shape anisotropy.Such enhancement facilitates the transformation of magnetic domain structures into in-plane configurations with strip-like features.Consequently,a large ratio between the out-of-plane and in-plane anisotropy(H_(out)/H_(in))and improved softness of the alloy can be achieved,providing valuable references for future fabrication of rare-earth(R)transition-metal(T)alloys with superior easy-plane characteristics.展开更多
Although the plastic loading can enhance creep deformation and yield strength,the anisotropic Stress Relaxation Aging(SRA)behavior and mechanism under plastic loading remain unclear,which presents a significant challe...Although the plastic loading can enhance creep deformation and yield strength,the anisotropic Stress Relaxation Aging(SRA)behavior and mechanism under plastic loading remain unclear,which presents a significant challenge in accurately shaping aluminum alloy panels.In this study,the SRA behavior of 2195-T4 Al-Cu-Li alloys were thoroughly studied under initial loading stresses within the elastic(210/250 MPa)and plastic(380/420 MPa)ranges at 180℃by stress relaxation and tensile tests as well as microstructure characterization.The findings reveal that compared with those under elastic loadings,in-plane anisotropy(IPA)values of the stress relaxation amount,yield strength and fracture elongation under plastic loadings are reduced by 60%–80%,70%–90% and 72%–89%,respectively.Similarly,IPA values of precipitate size in grains and PrecipitationFree Zones(PFZ)width at grain boundaries under plastic loading decrease by 31.4%and 94.4%respectively.These results indicate plastic loading significantly weakens the anisotropic SRA behavior,owing to numerous uniformly distributed fine T1phases and small IPA values of both T1precipitates size and PFZ width in various loading directions.Compared with those of elastic loadingaged alloys,yield strength of plastic loading-aged alloys shows high strength-ductility because of the combined effect of closely dispersed fine T1precipitates,narrowed PFZ and numerous sheared and rotated T1phases at different locations during tensile process.The uniformly distributed larger Kernel Average Misorientation(KAM)and Schmidt factor values of the plastic loading-aged alloy,as well as the cross-slip generated,also help to enhance the strength and ductility of the alloy.展开更多
The Tan-Lu Fault Zone is a large NNE-trending fault zone that has a substantial effect on the development of eastern China and its earthquake disaster prevention efforts. Aiming at the azimuthally anisotropic structur...The Tan-Lu Fault Zone is a large NNE-trending fault zone that has a substantial effect on the development of eastern China and its earthquake disaster prevention efforts. Aiming at the azimuthally anisotropic structure in the upper crust and seismogenic tectonics in the Hefei segment of this fault, we collected phase velocity dispersion data of fundamental mode Rayleigh waves from ambient noise cross-correlation functions of ~400 temporal seismographs in an area of approximately 80 × 70 km along the fault zone. The period band of the dispersion data was ~0.5–10 s. We inverted for the upper crustal three-dimensional(3-D) shear velocity model with azimuthal anisotropy from the surface to 10 km depth by using a 3-D direct azimuthal anisotropy inversion method. The inversion result shows the spatial distribution characteristics of the tectonic units in the upper crust. Additionally, the deformation of the Tan-Lu Fault Zone and its conjugated fault systems could be inferred from the anisotropy model. In particular, the faults that have remained active from the early and middle Pleistocene control the anisotropic characteristics of the upper crustal structure in this area. The direction of fast axes near the fault zone area in the upper crust is consistent with the strike of the faults, whereas for the region far away from the fault zone, the direction of fast axes is consistent with the direction of the regional principal stress caused by plate movement. Combined with the azimuthal anisotropy models in the deep crust and uppermost mantle from the surface wave and Pn wave, the different anisotropic patterns caused by the Tan-Lu Fault Zone and its conjugated fault system nearby are shown in the upper and lower crust. Furthermore,by using the double-difference method, we relocated the Lujiang earthquake series, which contained 32 earthquakes with a depth shallower than 10 km. Both the Vs model and earthquake relocation results indicate that earthquakes mostly occurred in the vicinity of structural boundaries with fractured media, with high-level development of cracks and small-scale faults jammed between more rigid areas.展开更多
Wire arc additive manufacturing(WAAM)is one of the most promising approaches to manufacturing large and complex metal components owing to its low cost and high efficiency.However,pores and coarse columnar grains cause...Wire arc additive manufacturing(WAAM)is one of the most promising approaches to manufacturing large and complex metal components owing to its low cost and high efficiency.However,pores and coarse columnar grains caused by thermal accumulation in WAAM significantly decrease the strength and increase the anisotropy,preventing the achievement of both high strength and isotropy.In this study,the strength and anisotropy of AlMg-Sc-Zr alloys were improved by regulating heat input.The results indicated that as the heat input increased from 60 to 99 J/mm,all the components had lower porosity(lower than 0.04%),the size of the Al_(3)(Sc_(1-x),Zr_(x))phases decreased,and the number density increased.The average grain size gradually decreased,and the grain morphologies transformed from coarse equiaxed grain(CEG)+fine equiaxed grain(FEG)to FEG owing to the increase in Al_(3)(Sc_(1-x),Zr_(x))phases with increasing heat input.After heat treatment at 325℃for 6 h,high-density dispersed Al_(3)Sc phases(<10 nm)precipitated.The alloy possessed the highest strength at 79 J/mm,ultimate tensile strength(UTS)of approximately 423±3 MPa,and in-plane anisotropy of approximately 4.3%.At a heat input of 99 J/mm,the in-plane anisotropy decreased to 1.2%and UTS reached 414±5 MPa.The reduction in the CEG prolonged the crack propagation path,which improved the UTS in the vertical direction and reduced the anisotropy.Theoretical calculations indicated that the main strengthening mechanisms were solid solution and precipitation strengthening.This study lays the theoretical foundations for WAAM-processed high-strength and isotropic Al alloy components.展开更多
To weaken the basal texture and in-plane anisotropy of magnesium alloy, non-basal slips are pre-enhanced by pre-rolling with a single pass larger strain reduction at elevated temperatures. Then Mg alloy sheets with th...To weaken the basal texture and in-plane anisotropy of magnesium alloy, non-basal slips are pre-enhanced by pre-rolling with a single pass larger strain reduction at elevated temperatures. Then Mg alloy sheets with the thickness of 1 mm are achieved after five passes rolling at 300 ℃. A double peak and disperse basal texture is generated after pre- rolling at higher temperatures when the non-basal slips are more active. So, the texture intensity of pre-rolled samples is reduced. Moreover, the distribution condition of in-grain misorientation axes (a method to analyze the activation of slips) shows that the pyramidal slip is quite active during deformation. After annealing on final rolled sheets, the texture distributions are changed and the intensity of texture reduces obviously due to static recrystallization. In particular, the r-value and in-plane anisotropy of pre-rolled samples are obviously lower than those of sample without pre-rolling.展开更多
This work investigated the anisotropy tensile properties of Inconel 625 alloy fabricated by laser powder bed fusion (LPBF) under various tests temperature, focusing the anisotropy evolution during the high temperature...This work investigated the anisotropy tensile properties of Inconel 625 alloy fabricated by laser powder bed fusion (LPBF) under various tests temperature, focusing the anisotropy evolution during the high temperature. The microstructure contained columnar grains with (111) texture in the vertical plane (90° sample), while a large equiaxed grain with (100) texture was produced in the horizontal plane (0° sample). As for 45° sample, a large number of equiaxed grains and a few columnar grains with (111) texture can be observed. The sample produced at a 0° orientation demonstrates the highest tensile strength, whereas the 90° sample exhibits the greatest elongation. Conversely, the 45° sample displays the least favorable overall performance. As the tests temperature increased from room temperature to 600℃, the anisotropy rate of ultimate tensile strength, yield strength and ductility between 0° and 45° samples, decreased from 8.98 to 6.96%, 2.36 to 1.28%, 19.93 to 12.23%, as well as between 0° and 90° samples decreased from 4.87 to 4.03%, 11.88 to 7.21% and 14.11 to 6.89%, respectively, because of the recovery of oriented columnar grains.展开更多
Three-dimensional printing(3DP)offers valuable insight into the characterization of natural rocks and the verification of theoretical models due to its high reproducibility and accurate replication of complex defects ...Three-dimensional printing(3DP)offers valuable insight into the characterization of natural rocks and the verification of theoretical models due to its high reproducibility and accurate replication of complex defects such as cracks and pores.In this study,3DP gypsum samples with different printing directions were subjected to a series of uniaxial compression tests with in situ micro-computed tomography(micro-CT)scanning to quantitatively investigate their mechanical anisotropic properties and damage evolution characteristics.Based on the two-dimensional(2D)CT images obtained at different scanning steps,a novel void ratio variable was derived using the mean value and variance of CT intensity.Additionally,a constitutive model was formulated incorporating the proposed damage variable,utilizing the void ratio variable.The crack evolution and crack morphology of 3DP gypsum samples were obtained and analyzed using the 3D models reconstructed from the CT images.The results indicate that 3DP gypsum samples exhibit mechanical anisotropic characteristics similar to those found in naturally sedimentary rocks.The mechanical anisotropy is attributed to the bedding planes formed between adjacent layers and pillar-like structures along the printing direction formed by CaSO_(4)·2H_(2)O crystals of needle-like morphology.The mean gray intensity of the voids has a positive linear relationship with the threshold value,while the CT variance and void ratio have concave and convex relationships,respectively.The constitutive model can effectively match the stress–strain curves obtained from uniaxial compression experiments.This study provides comprehensive explanations of the failure modes and anisotropic mechanisms of 3DP gypsum samples,which is important for characterizing and understanding the failure mechanism and microstructural evolution of 3DP rocks when modeling natural rock behavior.展开更多
This article presents a micro-structure tensor enhanced elasto-plastic finite element(FE)method to address strength anisotropy in three-dimensional(3D)soil slope stability analysis.The gravity increase method(GIM)is e...This article presents a micro-structure tensor enhanced elasto-plastic finite element(FE)method to address strength anisotropy in three-dimensional(3D)soil slope stability analysis.The gravity increase method(GIM)is employed to analyze the stability of 3D anisotropic soil slopes.The accuracy of the proposed method is first verified against the data in the literature.We then simulate the 3D soil slope with a straight slope surface and the convex and concave slope surfaces with a 90turning corner to study the 3D effect on slope stability and the failure mechanism under anisotropy conditions.Based on our numerical results,the end effect significantly impacts the failure mechanism and safety factor.Anisotropy degree notably affects the safety factor,with higher degrees leading to deeper landslides.For concave slopes,they can be approximated by straight slopes with suitable boundary conditions to assess their stability.Furthermore,a case study of the Saint-Alban test embankment A in Quebec,Canada,is provided to demonstrate the applicability of the proposed FE model.展开更多
The anisotropy and tension-compression asymmetry of rare-earth magnesium(Mg-RE) alloys have attracted significant attention.In this study,the room-temperature tensile anisotropy and tensioncompression asymmetry of the...The anisotropy and tension-compression asymmetry of rare-earth magnesium(Mg-RE) alloys have attracted significant attention.In this study,the room-temperature tensile anisotropy and tensioncompression asymmetry of the extruded Mg-8.5Gd-4.5Y-0.8Zn-0.4Zr alloy were investigated utilizing techniques such as optical microscopy(OM),electron backscatter diffraction(EBSD),and viscoplastic self-consistent(VPSC) modeling.Among the tensile samples,the TO sample(with axis parallel to extrusion direction) exhibits the greatest tensile yield strength(TYS) of 270 MPa and ultimate tensile strength(UTS) of 336 MPa,the T45 sample(with axis inclined at a 45° angle to extrusion direction) and T90 sample(with axis perpendicular to extrusion direction) exhibit lower TYS and UTS.The CO sample shows a slightly greater compressive yield strength(CYS) of 290 MPa.The ratio of TYS/CYS is approximately 1.07.This study significantly adjusts the VPSC hardening parameters through the Schmid factor of deformation mechanisms in Mg-RE alloy,particularly increasing the τ0(critical resolved shear stress,CRSS) and τ1values for basalslip and {10-12} twinning.The ratios of CRSS for other deformation mechanisms to basalslip are approximately as follows:CRSSTwin/CRSSBas=2,CRSSpri/CRSSBas≈2.7and CRSSPyr/CRSSBas≈3.3,while these ratios in traditional alloys are generally higher.The stress-strain curves and pole figures obtained from the modified VPSC model demonstrate excellent agreement with experimental results.According to the VPSC simulation results,the primary factor contributing to tensile anisotropy is the disparity in the activation levels of slip systems.The inclusion of rare-earth elements mitigates the tension-compression asymmetry by reducing the difference of CRSS between different deformation mechanisms.展开更多
Laser-induced electro-response(LIER),as a new method that complements conventional rock physics testing techniques,is expected to address issues such as of unclear mechanisms,model deficiency,inconsistent evaluation p...Laser-induced electro-response(LIER),as a new method that complements conventional rock physics testing techniques,is expected to address issues such as of unclear mechanisms,model deficiency,inconsistent evaluation parameters,and difficulty in separating multiple coupling factors in shale anisotropy evaluation,and establish a more complete and reliable shale physical property evaluation system.A testing strategy for out of plane anisotropy(OPA)was proposed for characterising anisotropy by LIER,where the near infrared(NIR)continuous laser(CL)and nanosecond pulsed laser(PL)were used to irradiate the surface of oblique cut shale,and the transverse LIER of the surface was measured.A LIER detection model is constructed from the laser-thermal effect,residual transverse polarization electric field and thermionic emission transport mechanism,which is strongly relying on laser power,bias voltage,and inclination angle of the measurement direction relative to the bedding plane of shale.For OPA test on the slice of oblique cut shale under CL irradiation,the relationship between the product of LIER simulation parameters and the tilting angle can be described by a cubic function and an impulse function with a maximum value at the threshold angle.In addition,the thermal accumulation and transient thermal effects are induced in the shale under a high-energy short laser pulse irradiation,and the simulation results indicate that there is an exponential relationship between the product of parameters in the LIER model and the tilt angle.Thus,for OPA test under CL and PL irradiations,it is recommended to use the product of parameters as an evaluation index for shale anisotropy.Furthermore,to solve the problem of multiple influencing factors entangled in the exponential term of the LIER model,the tangential LIER measurement was performed on the side of cylindrical shale core,where the provided LIER model effectively presented the anisotropy of tight shale plug,especially the effects of bias voltage and laser power on LIER were relatively separated as independent variables.Finally,the LIER at the end of laser drilling is presented well using the optimized model under a focused ns NIR PL irradiation,indicating that LIER is expected to be a real-time means for characterizing shale anisotropy during laser drilling processes.These results show that the present work is fundamental for the precise evaluation and effective development of anisotropic shale reservoirs,and will drive the advances of LIER in the exploration for shale oil and gas.展开更多
A heterogeneous transverse direction(TD)-tilt texture in rare-earth-containing magnesium plates typically results in obvious in-plane anisotropy in their mechanical behavior.In this study,the planar anisotropy of yiel...A heterogeneous transverse direction(TD)-tilt texture in rare-earth-containing magnesium plates typically results in obvious in-plane anisotropy in their mechanical behavior.In this study,the planar anisotropy of yield strength during tension along the rolling direction(RD)and TD is quantified in a Mg-0.1Zn-0.5Gd plate with different grain sizes and texture patterns.Regardless of the grain size,the yield strength along the RD is approximately 33 MPa higher than that along the TD in the plate with the c-axis distributed in an elliptical region.In contrast,a near in-plane isotropy of the mechanical properties is observed in the plate with the c-axis aligned primarily in a circular region.Microstructural analysis and crystal plasticity simulations show that basal slip prevailed during the tension test,with varied complementary deformation modes in different loading directions.Prismatic slip is the main complementary deformation mode during tension along the RD,whereas tensile twinning is important during tension along the TD.The yield anisotropy is primarily attributed to the varied interceptσ_(0)in the Hall-Petch relation during tension along different directions.The invariant Hall-Petch slope k results in grain size independence on the mechanical anisotropy.Finally,a quantitative discussion on the differences ofσ_(0)and the similarity in k related to the relative activity of the deformation modes is provided.展开更多
The pronounced anisotropy in mechanical properties presents a major obstacle to the extensive application of aluminum-lithium(Al-Li)alloys,primarily attributed to heterogeneous precipitate distribution,grain structure...The pronounced anisotropy in mechanical properties presents a major obstacle to the extensive application of aluminum-lithium(Al-Li)alloys,primarily attributed to heterogeneous precipitate distribution,grain structure variations,and crystallographic texture.This study investigates the impact of pre-thermal treatment prior to hot rolling and aging treatment on the anisotropy of mechanical properties of 2195 alloy sheet fabricated by gas atomization,hot pressing and hot rolling.The results demonstrate that pre-treatment at 450℃for 4 h promotes finer and more uniform distribution of precipitates,effectively mitigating mechanical anisotropy of the alloy sheet.Additionally,this treatment facilitates recrystallization during hot rolling,further reducing mechanical anisotropy.The in-plane anisotropy(IPA)factors for ultimate tensile strength(UTS)and yield strength(YS)are 1.15%and 0.77%,respectively.Subsequent aging treatment enhances grain refinement and the uniformity of the T_(1) phase,suppresses the formation of precipitation-free zones(PFZs),significantly improving the strength and toughness of the alloy sheet.After peak aging at 165℃for 48 h,the alloy sheet exhibits YS of 547 MPa,UTS of 590 MPa,and elongation(EL)of 7.7%.展开更多
Malachite,being highly hydrophilic and difficult to be floated conventionally,is usually beneficiated by sulfidation flotation in industry.However,the complex crystal structure of malachite leads to the formation of v...Malachite,being highly hydrophilic and difficult to be floated conventionally,is usually beneficiated by sulfidation flotation in industry.However,the complex crystal structure of malachite leads to the formation of various fracture surfaces with distinct properties during crushing and grinding,resulting in surface anisotropy.In this study,we explored the surface anisotropy of malachite and further investigated its sulfidation mechanism from the coordination chemistry perspective,considering the influence of the Jahn-Teller effect on malachite sulfidation.Computational results reveal that the penta-coordinated Cu ions on the malachite(201)and(010)surfaces exhibit stronger activity compared to those on the malachite(201)surface.Additionally,the tetra-coordinated structure formed by HS^(−)adsorption on the malachite(010)and(201)surfaces is more stable,with more negative adsorption energy,compared to the hexa coordinated structure formed by HS−adsorption on the(201)surface.The sulfidized malachite surface has an additional pair ofπelectron and smaller HOMO(highest occupied molecular orbital)-LUMO(lowest unoccupied molecular orbital)gap with xanthate molecules,causing strongerπbackbonding with xanthate.This study provides new insights into the surface sulfidation mechanism of malachite and offers a theoretical reference for the design of targeted flotation reagents.展开更多
Technological advancements and the emphasis on reducing the use of hazardous materials,such as Pb,have led to the widely use of Sn-based Pb-free solder in advanced packaging technology.With the miniaturization of sold...Technological advancements and the emphasis on reducing the use of hazardous materials,such as Pb,have led to the widely use of Sn-based Pb-free solder in advanced packaging technology.With the miniaturization of solder joints,Sn-based micro solder joints often contain single or limitedβ-Sn grains.The strong anisotropy ofβ-Sn,which is significantly correlated with the reliability of the micro solder joints during service,requires the development of methods for controlling the orientations of theseβ-Sn grains.In this review,we focus on the anisotropy of theβ-Sn grains in micro solder joints and the interactions betweenβ-Sn grain orientation and reliability issues concerning electromigration(EM),thermomigration(TM),EM+TM,corrosion process,tensile and shear creep behavior,thermal cycling(TC)and cryogenic temperature.Furthermore,we summarize the strategies for controlling theβ-Sn orientation in micro solder joints.The methods include changing the solder joint size and composition,adding additives,nucleating on specific substrates and interfacial intermetallic compounds,with the aid of external loads during solidification process and introducing heredity effect of theβ-Sn texture during multi-reflow.Finally,the{101}and{301}twinning models with∼60°rotations about a common〈100〉are adopted to explain the mechanism ofβ-Sn grain nucleation and morphology.The shortcomings of the existing methods and the further potential for the development in the field are discussed to promote the application of Pb-free solders in advanced packaging.展开更多
Mg alloy often undergoes shear deformation during industrial processing.While its anisotropy and tension-compression asymmetry have been thoroughly studied under uniaxial loading,the understanding for shear loading is...Mg alloy often undergoes shear deformation during industrial processing.While its anisotropy and tension-compression asymmetry have been thoroughly studied under uniaxial loading,the understanding for shear loading is still lacking.This study employed a rolled AZ31B plate with typical basal texture to investigate the shear behaviors.Positive and negative simple shear experiments were performed at different angles in the transverse plane,whereby the visco-plastic self-consistent model was calibrated to reveal the deformation mechanisms and predict the mechanical responses at various orientations.Positive-negative shear asymmetry is present because extension twinning preferentially operates in one shear direction but is suppressed in the opposite direction.Simple shear induces multiple twin variants,thus impedes twin growth and slows the consumption of matrix,as compared to in-plane compression.For slip dominated simple shear,the interaction between loading-induced rigid body rotation and slip-induced crystal rotation produces distinct hardening behaviors,namely orthogonally asymmetric mechanical responses at complementary loading angles,which is largely absent in uniaxial loading.Finally,simulation results verify that positive-negative shear asymmetry appears only when the deviatoric normal stress on the sheet plane is non-zero.Positive-negative shear asymmetry persists except for the conditions of shear plane parallel to sheet plane,or shear direction parallel or perpendicular to rolling direction.展开更多
Longitudinal magnetic field annealing is utilized for modifying the magnetic anisotropy and enhancing the magnetic softness of Fe_(75)Co_(8)(B_(10)Si_(3)C_(3)P_(1))_(1-x)/_(17)Cux(x=0.5,0.75,1,1.25)nanocrystalline all...Longitudinal magnetic field annealing is utilized for modifying the magnetic anisotropy and enhancing the magnetic softness of Fe_(75)Co_(8)(B_(10)Si_(3)C_(3)P_(1))_(1-x)/_(17)Cux(x=0.5,0.75,1,1.25)nanocrystalline alloys.All of the magnetic field-annealed nanocrystalline alloys with Cu content more than 0.5 at.%exhibit significantly improved soft-magnetic properties,including high saturation magnetic flux density up to 1.87 T,effective permeability of 13,000-16,000 under the condition of 1 A/m and 1 kHz,coercivity as low as 1.6 A/m,and core loss of 0.11-0.45 W/kg under the condition of 1.0 T and 50 Hz.The application of a magnetic field promotes the nucleation and inhibits the growth of grains,leading to an increase in the number density of nanocrystals and the crystalline volume fraction,and a reduction in the grain size.The magnetic field annealing reduces the effective magneto-crystalline anisotropy energy to 2-4 J/m^(3),and induces longitudinal magnetic anisotropy with anisotropy energy density of 400-900 J/m^(3)which shows dependence on the crystalline volume fraction.The field-induced magnetic anisotropy dominates over the random local magnetic anisotropies,and results in the formation of regular magnetic domains aligned longitudinally,pinning-free domain wall displacement,and thus enhanced soft-magnetic properties.展开更多
基金National Natural Science Foundation of China(51504138,51674118,52271177)Hunan Provincial Natural Science Foundation of China(2023JJ50181)Supported by State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology(P2024-022)。
文摘To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the alloy across different planes were investigated.The anisotropy of SLM-fabricated Ti-6Al-4V alloys was analyzed,and the electron backscatter diffraction technique was used to investigate the influence of different grain types and orientations on the stress-strain distribution at various scales.Results reveal that in room-temperature compression tests at a strain rate of 10^(-3) s^(-1),both the compressive yield strength and microhardness vary along the deposition direction,indicating a certain degree of mechanical property anisotropy.The alloy exhibits a columnar microstructure;along the deposition direction,the grains appear equiaxed,and they have internal hexagonal close-packed(hcp)α/α'martensitic structure.α'phase has a preferential orientation approximately along the<0001>direction.Anisotropy arises from the high aspect ratio of columnar grains,along with the weak texture of the microstructure and low symmetry of the hcp crystal structure.
基金supported by the National Natural Science Foundation of China(Grant Nos.12488201,12274390,12304035,and 51627901)the Anhui Initiative in Quantum Information Technologies(Grant No.AHY160000)+3 种基金the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302802)the National Key R&D Program of the MOST of China(Grant No.2022YFA1602600)the Basic Research Program of the Chinese Academy of Sciences Based on Major Scientific Infrastructures(Grant No.JZHKYPT-2021-08)the National Key R&D Program of China(Grant No.2023YFA1607701)。
文摘Chiral magnets have attracted considerable attention due to their intricate magnetic properties,among which B20compounds constitute a quintessential class that has gained significant focus,particularly in the study of skyrmions.MnGe,as a member of the B20 family,exhibits a more complex magnetic structure compared with other materials with similar crystal structures.In this work,we successfully synthesized high-quality MnGe thin films and characterized their magnetoresistance,M-H curves,magneto-Seebeck effect,and magnetic force microscopy(MFM)images,all of which demonstrate pronounced magnetic anisotropy.Notably,the Seebeck coefficient exhibits a plateau at low magnetic fields when the magnetic field is applied in the film plane,indicating a field region in which the magnetic structure remains stable.MFM imaging further reveals magnetic transitions within the MnGe films when the magnetic field is oriented along the film plane.These findings are crucial for advancing our understanding of the magnetic ground state of MnGe and the evolution of its magnetic structure under an applied external magnetic field.
基金supported by the Beijing Natural Science Foundation(Grant No.Z230006)the National Key Research and Development Program of China(Grant No.2022YFA1204000)the National Natural Science Foundation of China(Grant Nos.12274405 and 12393831)。
文摘We report the development of the[Pt_(0.75)Ti_(0.25)/Co-Ni multilayer/Ta]_n superlattice with strong spin-orbit torque,large perpendicular magnetic anisotropy,and remarkably low switching current density.We demonstrate that the efficiency of the spin-orbit torque increases nearly linearly with the repetition number n,which is in excellent agreement with the spin Hall effect of the Pt_(0.75)Ti_(0.25)being essentially the only source of the observed spin-orbit torque.The perpendicular magnetic anisotropy field is also substantially enhanced by more than a factor of 2 as n increases from 1 to6.The[Pt_(0.75)Ti_(0.25)/Co-Ni multilayers/Ta]_n superlattice additionally exhibits deterministic,low-current-density magnetization switching despite the very large total layer thicknesses.The unique combination of strong spin-orbit torque,robust perpendicular magnetic anisotropy,low-current-density switching,and excellent high thermal stability makes the[Pt_(0.75)Ti_(0.25)/Co-Ni multilayer/Ta]_n superlattice a highly compelling material candidate for ultrafast,energy-efficient,and long-data-retention spintronic technologies.
基金supported by the Natural Science Foundation of Heilongjiang Province(No.JQ2022E004).
文摘Conventional cross rolling is influenced by the force couple effect of symmetrical rollers,resulting in the c-axis of the plate grains being oriented perpendicular to the rolling surface.This orientation contributes to a high degree of work hardening and mechanical anisotropy,thereby complicating subsequent processing.In this study,the hard plate cross rolling(HP-CR)process is put forward for the first time,and the microstructure evolution and mechanical properties of rolled AZ31 Magnesium plate were analyzed.The results indicate that,in comparison to traditional cross rolling(CR),the average grain size of the HP-CR is refined to 5.33µm.Additionally,the average yield strength and elongation of the sheet are enhanced by 15.2%and 35.2%,respectively,while the average tensile strength is 283 MPa,and the r value decreases by 39.8%.These changes are attributed to the combined effects of grain refinement,microstructural homogenization,and basal texture weakening.On the one hand,the substantial energy stored in the original lattice distortion serves as a driving force for the dynamic recrystallization process,facilitating the elimination of the deformed grain structure.This process increases the proportion of recrystallized grains from 5%to 82%,reduces the degree of work hardening,and correspondingly decreases the density of geometrically necessary dislocations(ρ^(GND))by 70.8%,accompanied by the formation of high-angle grain boundaries(HAGB).On the other hand,dynamic recrystallization promotes grain rearrangement,resulting in an increased number of grains oriented in the transverse direction(TD),which diminishes the texture strength of the basal plane.Concurrently,the activation of non-basal slip systems reduces the resistance to dislocation sliding in various directions,significantly reduces the degree of mechanical anisotropy and enhancing the plastic deformation capacity of the plate.This research provides valuable scientific insights and technical foundations for the large-scale manufacturing of high-performance AZ31 magnesium alloy sheets.
基金supported by the National Key R&D Program of China(No.2021YFB3501303)the National Natural Science Foundation of China(Nos.52122106 and U23A20547)+2 种基金the"Pioneer"R&D Program of Zhejiang Province(No.2022C01230)Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(No.2021SZ-FR005)the Space Application System of China Manned Space Program(No.KJZ-YY-NCL03).
文摘The prevalence of wide-bandgap semiconductors urges the development of advanced soft magnetic materials for high-frequency applications.While soft magnetic alloys are limited by resonances at elevated frequencies,the incorporation of planar anisotropy serves as an effective strategy to overcome this dilemma and extend their potential for high-frequency applications.Herein,nanocrystalline Y_(2)Co_(14)B alloys have been designed with tuned magnetocrystalline and shape bi-anisotropy via melt spinning and magnetic field-assisted annealing.With the application of zero,transverse,rotational and longitudinal magnetic fields(denoted as ZFA,TFA,RFA and LFA),the effects of field direction and annealing time on microstructural and performance evolution have been investigated.Compared with ZFA,magnetic field-assisted annealing not only promotes the growth of nanograins but also alters the coincidence degree between intrinsic easy-plane(IEP)and artificial easy-plane(AEP)structures.While the random distribution of IEP structure is achieved for the RFA due to the formation of non-orientated nanograins,directional magnetic field-assisted annealing contributes to preferentially orientated(006)nanograins,especially for the LFA,resulting in optimal coincidence between the magnetocrystalline anisotropy and shape anisotropy.Such enhancement facilitates the transformation of magnetic domain structures into in-plane configurations with strip-like features.Consequently,a large ratio between the out-of-plane and in-plane anisotropy(H_(out)/H_(in))and improved softness of the alloy can be achieved,providing valuable references for future fabrication of rare-earth(R)transition-metal(T)alloys with superior easy-plane characteristics.
基金support from the Key Program of the National Natural Science Foundation of China(No.51235010)。
文摘Although the plastic loading can enhance creep deformation and yield strength,the anisotropic Stress Relaxation Aging(SRA)behavior and mechanism under plastic loading remain unclear,which presents a significant challenge in accurately shaping aluminum alloy panels.In this study,the SRA behavior of 2195-T4 Al-Cu-Li alloys were thoroughly studied under initial loading stresses within the elastic(210/250 MPa)and plastic(380/420 MPa)ranges at 180℃by stress relaxation and tensile tests as well as microstructure characterization.The findings reveal that compared with those under elastic loadings,in-plane anisotropy(IPA)values of the stress relaxation amount,yield strength and fracture elongation under plastic loadings are reduced by 60%–80%,70%–90% and 72%–89%,respectively.Similarly,IPA values of precipitate size in grains and PrecipitationFree Zones(PFZ)width at grain boundaries under plastic loading decrease by 31.4%and 94.4%respectively.These results indicate plastic loading significantly weakens the anisotropic SRA behavior,owing to numerous uniformly distributed fine T1phases and small IPA values of both T1precipitates size and PFZ width in various loading directions.Compared with those of elastic loadingaged alloys,yield strength of plastic loading-aged alloys shows high strength-ductility because of the combined effect of closely dispersed fine T1precipitates,narrowed PFZ and numerous sheared and rotated T1phases at different locations during tensile process.The uniformly distributed larger Kernel Average Misorientation(KAM)and Schmidt factor values of the plastic loading-aged alloy,as well as the cross-slip generated,also help to enhance the strength and ductility of the alloy.
基金financially supported by the National Key Research and Development Program of China (2022YFC3005600)the Foundation of the Anhui Educational Commission (2023AH051198)+1 种基金the National Natural Science Foundation of China (42125401 and 42104063)the Joint Open Fund of Mengcheng National Geophysical Observatory (MENGO-202201)。
文摘The Tan-Lu Fault Zone is a large NNE-trending fault zone that has a substantial effect on the development of eastern China and its earthquake disaster prevention efforts. Aiming at the azimuthally anisotropic structure in the upper crust and seismogenic tectonics in the Hefei segment of this fault, we collected phase velocity dispersion data of fundamental mode Rayleigh waves from ambient noise cross-correlation functions of ~400 temporal seismographs in an area of approximately 80 × 70 km along the fault zone. The period band of the dispersion data was ~0.5–10 s. We inverted for the upper crustal three-dimensional(3-D) shear velocity model with azimuthal anisotropy from the surface to 10 km depth by using a 3-D direct azimuthal anisotropy inversion method. The inversion result shows the spatial distribution characteristics of the tectonic units in the upper crust. Additionally, the deformation of the Tan-Lu Fault Zone and its conjugated fault systems could be inferred from the anisotropy model. In particular, the faults that have remained active from the early and middle Pleistocene control the anisotropic characteristics of the upper crustal structure in this area. The direction of fast axes near the fault zone area in the upper crust is consistent with the strike of the faults, whereas for the region far away from the fault zone, the direction of fast axes is consistent with the direction of the regional principal stress caused by plate movement. Combined with the azimuthal anisotropy models in the deep crust and uppermost mantle from the surface wave and Pn wave, the different anisotropic patterns caused by the Tan-Lu Fault Zone and its conjugated fault system nearby are shown in the upper and lower crust. Furthermore,by using the double-difference method, we relocated the Lujiang earthquake series, which contained 32 earthquakes with a depth shallower than 10 km. Both the Vs model and earthquake relocation results indicate that earthquakes mostly occurred in the vicinity of structural boundaries with fractured media, with high-level development of cracks and small-scale faults jammed between more rigid areas.
基金supported by National Key Research and Development Program(Grant No.2024YFB4609700)the National Natural Science Foundation of China(Grant No.52374365)。
文摘Wire arc additive manufacturing(WAAM)is one of the most promising approaches to manufacturing large and complex metal components owing to its low cost and high efficiency.However,pores and coarse columnar grains caused by thermal accumulation in WAAM significantly decrease the strength and increase the anisotropy,preventing the achievement of both high strength and isotropy.In this study,the strength and anisotropy of AlMg-Sc-Zr alloys were improved by regulating heat input.The results indicated that as the heat input increased from 60 to 99 J/mm,all the components had lower porosity(lower than 0.04%),the size of the Al_(3)(Sc_(1-x),Zr_(x))phases decreased,and the number density increased.The average grain size gradually decreased,and the grain morphologies transformed from coarse equiaxed grain(CEG)+fine equiaxed grain(FEG)to FEG owing to the increase in Al_(3)(Sc_(1-x),Zr_(x))phases with increasing heat input.After heat treatment at 325℃for 6 h,high-density dispersed Al_(3)Sc phases(<10 nm)precipitated.The alloy possessed the highest strength at 79 J/mm,ultimate tensile strength(UTS)of approximately 423±3 MPa,and in-plane anisotropy of approximately 4.3%.At a heat input of 99 J/mm,the in-plane anisotropy decreased to 1.2%and UTS reached 414±5 MPa.The reduction in the CEG prolonged the crack propagation path,which improved the UTS in the vertical direction and reduced the anisotropy.Theoretical calculations indicated that the main strengthening mechanisms were solid solution and precipitation strengthening.This study lays the theoretical foundations for WAAM-processed high-strength and isotropic Al alloy components.
基金Project(52374395) supported by the National Natural Science Foundations of ChinaProjects(20210302123135,20210302123163) supported by the Natural Science Foundation of Shanxi Province,China+2 种基金Projects(YDZJSX20231B003,YDZJSX2021A010) supported by the Central Government Guided Local Science and Technology Development Projects,ChinaProject(2022M710541) supported by the China Postdoctoral Science FoundationProjects(202104021301022,202204021301009) supported by the Scientific and Technological Achievements Transformation Guidance Special Project of Shanxi Province,China。
文摘To weaken the basal texture and in-plane anisotropy of magnesium alloy, non-basal slips are pre-enhanced by pre-rolling with a single pass larger strain reduction at elevated temperatures. Then Mg alloy sheets with the thickness of 1 mm are achieved after five passes rolling at 300 ℃. A double peak and disperse basal texture is generated after pre- rolling at higher temperatures when the non-basal slips are more active. So, the texture intensity of pre-rolled samples is reduced. Moreover, the distribution condition of in-grain misorientation axes (a method to analyze the activation of slips) shows that the pyramidal slip is quite active during deformation. After annealing on final rolled sheets, the texture distributions are changed and the intensity of texture reduces obviously due to static recrystallization. In particular, the r-value and in-plane anisotropy of pre-rolled samples are obviously lower than those of sample without pre-rolling.
基金supported by the National Natural Science Foundation of China(Grant Nos.52205140,52175129)the Outstanding Youth Foundation of Hunan Province(Grant No.2023JJ20041)the Science and Technology Innovation Program of Hunan Province(2023RC3241).
文摘This work investigated the anisotropy tensile properties of Inconel 625 alloy fabricated by laser powder bed fusion (LPBF) under various tests temperature, focusing the anisotropy evolution during the high temperature. The microstructure contained columnar grains with (111) texture in the vertical plane (90° sample), while a large equiaxed grain with (100) texture was produced in the horizontal plane (0° sample). As for 45° sample, a large number of equiaxed grains and a few columnar grains with (111) texture can be observed. The sample produced at a 0° orientation demonstrates the highest tensile strength, whereas the 90° sample exhibits the greatest elongation. Conversely, the 45° sample displays the least favorable overall performance. As the tests temperature increased from room temperature to 600℃, the anisotropy rate of ultimate tensile strength, yield strength and ductility between 0° and 45° samples, decreased from 8.98 to 6.96%, 2.36 to 1.28%, 19.93 to 12.23%, as well as between 0° and 90° samples decreased from 4.87 to 4.03%, 11.88 to 7.21% and 14.11 to 6.89%, respectively, because of the recovery of oriented columnar grains.
基金supported by grants from the Human Resources Development program(Grant No.20204010600250)the Training Program of CCUS for the Green Growth(Grant No.20214000000500)by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)funded by the Ministry of Trade,Industry,and Energy of the Korean Government(MOTIE).
文摘Three-dimensional printing(3DP)offers valuable insight into the characterization of natural rocks and the verification of theoretical models due to its high reproducibility and accurate replication of complex defects such as cracks and pores.In this study,3DP gypsum samples with different printing directions were subjected to a series of uniaxial compression tests with in situ micro-computed tomography(micro-CT)scanning to quantitatively investigate their mechanical anisotropic properties and damage evolution characteristics.Based on the two-dimensional(2D)CT images obtained at different scanning steps,a novel void ratio variable was derived using the mean value and variance of CT intensity.Additionally,a constitutive model was formulated incorporating the proposed damage variable,utilizing the void ratio variable.The crack evolution and crack morphology of 3DP gypsum samples were obtained and analyzed using the 3D models reconstructed from the CT images.The results indicate that 3DP gypsum samples exhibit mechanical anisotropic characteristics similar to those found in naturally sedimentary rocks.The mechanical anisotropy is attributed to the bedding planes formed between adjacent layers and pillar-like structures along the printing direction formed by CaSO_(4)·2H_(2)O crystals of needle-like morphology.The mean gray intensity of the voids has a positive linear relationship with the threshold value,while the CT variance and void ratio have concave and convex relationships,respectively.The constitutive model can effectively match the stress–strain curves obtained from uniaxial compression experiments.This study provides comprehensive explanations of the failure modes and anisotropic mechanisms of 3DP gypsum samples,which is important for characterizing and understanding the failure mechanism and microstructural evolution of 3DP rocks when modeling natural rock behavior.
基金supported by the National Natural Science Foundation of China(Grant Nos.51890912,51979025 and 52011530189).
文摘This article presents a micro-structure tensor enhanced elasto-plastic finite element(FE)method to address strength anisotropy in three-dimensional(3D)soil slope stability analysis.The gravity increase method(GIM)is employed to analyze the stability of 3D anisotropic soil slopes.The accuracy of the proposed method is first verified against the data in the literature.We then simulate the 3D soil slope with a straight slope surface and the convex and concave slope surfaces with a 90turning corner to study the 3D effect on slope stability and the failure mechanism under anisotropy conditions.Based on our numerical results,the end effect significantly impacts the failure mechanism and safety factor.Anisotropy degree notably affects the safety factor,with higher degrees leading to deeper landslides.For concave slopes,they can be approximated by straight slopes with suitable boundary conditions to assess their stability.Furthermore,a case study of the Saint-Alban test embankment A in Quebec,Canada,is provided to demonstrate the applicability of the proposed FE model.
基金Project supported by the Key Research and Development Program of Heilongjiang (2022ZX01A01)National Natural Science Foundation of China (51975167)Natural Science Foundation of Heilongjiang Province(LH2022E080)
文摘The anisotropy and tension-compression asymmetry of rare-earth magnesium(Mg-RE) alloys have attracted significant attention.In this study,the room-temperature tensile anisotropy and tensioncompression asymmetry of the extruded Mg-8.5Gd-4.5Y-0.8Zn-0.4Zr alloy were investigated utilizing techniques such as optical microscopy(OM),electron backscatter diffraction(EBSD),and viscoplastic self-consistent(VPSC) modeling.Among the tensile samples,the TO sample(with axis parallel to extrusion direction) exhibits the greatest tensile yield strength(TYS) of 270 MPa and ultimate tensile strength(UTS) of 336 MPa,the T45 sample(with axis inclined at a 45° angle to extrusion direction) and T90 sample(with axis perpendicular to extrusion direction) exhibit lower TYS and UTS.The CO sample shows a slightly greater compressive yield strength(CYS) of 290 MPa.The ratio of TYS/CYS is approximately 1.07.This study significantly adjusts the VPSC hardening parameters through the Schmid factor of deformation mechanisms in Mg-RE alloy,particularly increasing the τ0(critical resolved shear stress,CRSS) and τ1values for basalslip and {10-12} twinning.The ratios of CRSS for other deformation mechanisms to basalslip are approximately as follows:CRSSTwin/CRSSBas=2,CRSSpri/CRSSBas≈2.7and CRSSPyr/CRSSBas≈3.3,while these ratios in traditional alloys are generally higher.The stress-strain curves and pole figures obtained from the modified VPSC model demonstrate excellent agreement with experimental results.According to the VPSC simulation results,the primary factor contributing to tensile anisotropy is the disparity in the activation levels of slip systems.The inclusion of rare-earth elements mitigates the tension-compression asymmetry by reducing the difference of CRSS between different deformation mechanisms.
基金supported by the National Natural Science Foundation of China(Nos.12374412 and 12404502).
文摘Laser-induced electro-response(LIER),as a new method that complements conventional rock physics testing techniques,is expected to address issues such as of unclear mechanisms,model deficiency,inconsistent evaluation parameters,and difficulty in separating multiple coupling factors in shale anisotropy evaluation,and establish a more complete and reliable shale physical property evaluation system.A testing strategy for out of plane anisotropy(OPA)was proposed for characterising anisotropy by LIER,where the near infrared(NIR)continuous laser(CL)and nanosecond pulsed laser(PL)were used to irradiate the surface of oblique cut shale,and the transverse LIER of the surface was measured.A LIER detection model is constructed from the laser-thermal effect,residual transverse polarization electric field and thermionic emission transport mechanism,which is strongly relying on laser power,bias voltage,and inclination angle of the measurement direction relative to the bedding plane of shale.For OPA test on the slice of oblique cut shale under CL irradiation,the relationship between the product of LIER simulation parameters and the tilting angle can be described by a cubic function and an impulse function with a maximum value at the threshold angle.In addition,the thermal accumulation and transient thermal effects are induced in the shale under a high-energy short laser pulse irradiation,and the simulation results indicate that there is an exponential relationship between the product of parameters in the LIER model and the tilt angle.Thus,for OPA test under CL and PL irradiations,it is recommended to use the product of parameters as an evaluation index for shale anisotropy.Furthermore,to solve the problem of multiple influencing factors entangled in the exponential term of the LIER model,the tangential LIER measurement was performed on the side of cylindrical shale core,where the provided LIER model effectively presented the anisotropy of tight shale plug,especially the effects of bias voltage and laser power on LIER were relatively separated as independent variables.Finally,the LIER at the end of laser drilling is presented well using the optimized model under a focused ns NIR PL irradiation,indicating that LIER is expected to be a real-time means for characterizing shale anisotropy during laser drilling processes.These results show that the present work is fundamental for the precise evaluation and effective development of anisotropic shale reservoirs,and will drive the advances of LIER in the exploration for shale oil and gas.
基金support of the National Key Research and Development Program of China(No.2022YFB3707102)the Key Project of Jiangsu Basic Research Program(No.BK20243005)the Basic Research Program of Jiangsu(No.BK20232025).
文摘A heterogeneous transverse direction(TD)-tilt texture in rare-earth-containing magnesium plates typically results in obvious in-plane anisotropy in their mechanical behavior.In this study,the planar anisotropy of yield strength during tension along the rolling direction(RD)and TD is quantified in a Mg-0.1Zn-0.5Gd plate with different grain sizes and texture patterns.Regardless of the grain size,the yield strength along the RD is approximately 33 MPa higher than that along the TD in the plate with the c-axis distributed in an elliptical region.In contrast,a near in-plane isotropy of the mechanical properties is observed in the plate with the c-axis aligned primarily in a circular region.Microstructural analysis and crystal plasticity simulations show that basal slip prevailed during the tension test,with varied complementary deformation modes in different loading directions.Prismatic slip is the main complementary deformation mode during tension along the RD,whereas tensile twinning is important during tension along the TD.The yield anisotropy is primarily attributed to the varied interceptσ_(0)in the Hall-Petch relation during tension along different directions.The invariant Hall-Petch slope k results in grain size independence on the mechanical anisotropy.Finally,a quantitative discussion on the differences ofσ_(0)and the similarity in k related to the relative activity of the deformation modes is provided.
基金Project(52274369)supported by the National Natural Science Foundation of ChinaProject(623020034)supported by the National Key Laboratory of Science and Technology on High-strength Structural Materials,China。
文摘The pronounced anisotropy in mechanical properties presents a major obstacle to the extensive application of aluminum-lithium(Al-Li)alloys,primarily attributed to heterogeneous precipitate distribution,grain structure variations,and crystallographic texture.This study investigates the impact of pre-thermal treatment prior to hot rolling and aging treatment on the anisotropy of mechanical properties of 2195 alloy sheet fabricated by gas atomization,hot pressing and hot rolling.The results demonstrate that pre-treatment at 450℃for 4 h promotes finer and more uniform distribution of precipitates,effectively mitigating mechanical anisotropy of the alloy sheet.Additionally,this treatment facilitates recrystallization during hot rolling,further reducing mechanical anisotropy.The in-plane anisotropy(IPA)factors for ultimate tensile strength(UTS)and yield strength(YS)are 1.15%and 0.77%,respectively.Subsequent aging treatment enhances grain refinement and the uniformity of the T_(1) phase,suppresses the formation of precipitation-free zones(PFZs),significantly improving the strength and toughness of the alloy sheet.After peak aging at 165℃for 48 h,the alloy sheet exhibits YS of 547 MPa,UTS of 590 MPa,and elongation(EL)of 7.7%.
基金Projects(52074356,U22A20170)supported by the National Natural Science Foundation of ChinaProject(2022YFC2904503)supported by the National Key R&D Program of China+4 种基金Project(2023SK2061)supported by the Special Fund for the Construction of Hunan Innovative Province,ChinaProject(2023CXQD002)supported by the Innovation-driven Project of Central South University,ChinaProject(2022RC1183)supported by the Science and Technology Innovation Program of Hunan Province,ChinaProject(kq2009005)supported by the Changsha Science and Technology Project(Changsha Outstanding Innovative Youth Training Program),ChinaProject supported by the High-performance Computing Centers of Central South University,China。
文摘Malachite,being highly hydrophilic and difficult to be floated conventionally,is usually beneficiated by sulfidation flotation in industry.However,the complex crystal structure of malachite leads to the formation of various fracture surfaces with distinct properties during crushing and grinding,resulting in surface anisotropy.In this study,we explored the surface anisotropy of malachite and further investigated its sulfidation mechanism from the coordination chemistry perspective,considering the influence of the Jahn-Teller effect on malachite sulfidation.Computational results reveal that the penta-coordinated Cu ions on the malachite(201)and(010)surfaces exhibit stronger activity compared to those on the malachite(201)surface.Additionally,the tetra-coordinated structure formed by HS^(−)adsorption on the malachite(010)and(201)surfaces is more stable,with more negative adsorption energy,compared to the hexa coordinated structure formed by HS−adsorption on the(201)surface.The sulfidized malachite surface has an additional pair ofπelectron and smaller HOMO(highest occupied molecular orbital)-LUMO(lowest unoccupied molecular orbital)gap with xanthate molecules,causing strongerπbackbonding with xanthate.This study provides new insights into the surface sulfidation mechanism of malachite and offers a theoretical reference for the design of targeted flotation reagents.
基金financially supported by the National Natural Science Foundation of China(No.52075072)the Provincial Applied Basic Research Program of Liaoning Provincial Department of Science and Technology(No.2023JH2/101300181)the Key R&D Program of Shandong Province,China(No.2022CXGC020408)。
文摘Technological advancements and the emphasis on reducing the use of hazardous materials,such as Pb,have led to the widely use of Sn-based Pb-free solder in advanced packaging technology.With the miniaturization of solder joints,Sn-based micro solder joints often contain single or limitedβ-Sn grains.The strong anisotropy ofβ-Sn,which is significantly correlated with the reliability of the micro solder joints during service,requires the development of methods for controlling the orientations of theseβ-Sn grains.In this review,we focus on the anisotropy of theβ-Sn grains in micro solder joints and the interactions betweenβ-Sn grain orientation and reliability issues concerning electromigration(EM),thermomigration(TM),EM+TM,corrosion process,tensile and shear creep behavior,thermal cycling(TC)and cryogenic temperature.Furthermore,we summarize the strategies for controlling theβ-Sn orientation in micro solder joints.The methods include changing the solder joint size and composition,adding additives,nucleating on specific substrates and interfacial intermetallic compounds,with the aid of external loads during solidification process and introducing heredity effect of theβ-Sn texture during multi-reflow.Finally,the{101}and{301}twinning models with∼60°rotations about a common〈100〉are adopted to explain the mechanism ofβ-Sn grain nucleation and morphology.The shortcomings of the existing methods and the further potential for the development in the field are discussed to promote the application of Pb-free solders in advanced packaging.
基金supports of the National Key Research and Development Program of China(Grant No.2023YFB3710900)the National Natural Science Foundation of China(Grant Nos.52071211 and 52071208)。
文摘Mg alloy often undergoes shear deformation during industrial processing.While its anisotropy and tension-compression asymmetry have been thoroughly studied under uniaxial loading,the understanding for shear loading is still lacking.This study employed a rolled AZ31B plate with typical basal texture to investigate the shear behaviors.Positive and negative simple shear experiments were performed at different angles in the transverse plane,whereby the visco-plastic self-consistent model was calibrated to reveal the deformation mechanisms and predict the mechanical responses at various orientations.Positive-negative shear asymmetry is present because extension twinning preferentially operates in one shear direction but is suppressed in the opposite direction.Simple shear induces multiple twin variants,thus impedes twin growth and slows the consumption of matrix,as compared to in-plane compression.For slip dominated simple shear,the interaction between loading-induced rigid body rotation and slip-induced crystal rotation produces distinct hardening behaviors,namely orthogonally asymmetric mechanical responses at complementary loading angles,which is largely absent in uniaxial loading.Finally,simulation results verify that positive-negative shear asymmetry appears only when the deviatoric normal stress on the sheet plane is non-zero.Positive-negative shear asymmetry persists except for the conditions of shear plane parallel to sheet plane,or shear direction parallel or perpendicular to rolling direction.
基金supported by the National Key R&D Program of China(No.2022YFB3804100)the National Natural Science Foundation of China(No.52231005)+1 种基金the Jiangsu Provincial Key R&D Program(No.BE2021088)the Start-up Research Fund of Southeast University(No.RF1028623113).
文摘Longitudinal magnetic field annealing is utilized for modifying the magnetic anisotropy and enhancing the magnetic softness of Fe_(75)Co_(8)(B_(10)Si_(3)C_(3)P_(1))_(1-x)/_(17)Cux(x=0.5,0.75,1,1.25)nanocrystalline alloys.All of the magnetic field-annealed nanocrystalline alloys with Cu content more than 0.5 at.%exhibit significantly improved soft-magnetic properties,including high saturation magnetic flux density up to 1.87 T,effective permeability of 13,000-16,000 under the condition of 1 A/m and 1 kHz,coercivity as low as 1.6 A/m,and core loss of 0.11-0.45 W/kg under the condition of 1.0 T and 50 Hz.The application of a magnetic field promotes the nucleation and inhibits the growth of grains,leading to an increase in the number density of nanocrystals and the crystalline volume fraction,and a reduction in the grain size.The magnetic field annealing reduces the effective magneto-crystalline anisotropy energy to 2-4 J/m^(3),and induces longitudinal magnetic anisotropy with anisotropy energy density of 400-900 J/m^(3)which shows dependence on the crystalline volume fraction.The field-induced magnetic anisotropy dominates over the random local magnetic anisotropies,and results in the formation of regular magnetic domains aligned longitudinally,pinning-free domain wall displacement,and thus enhanced soft-magnetic properties.
