The functional properties of glasses are governed by their formation history and the complex relaxation processes they undergo.However,under extreme conditions,glass behaviors are still elusive.In this study,we employ...The functional properties of glasses are governed by their formation history and the complex relaxation processes they undergo.However,under extreme conditions,glass behaviors are still elusive.In this study,we employ simulations with varied protocols to evaluate the effectiveness of different descriptors in predicting mechanical properties across both low-and high-pressure regimes.Our findings demonstrate that conventional structural and configurational descriptors fail to correlate with the mechanical response following pressure release,whereas the activation energy descriptor exhibits robust linearity with shear modulus after correcting for pressure effects.Notably,the soft mode parameter emerges as an ideal and computationally efficient alternative for capturing this mechanical behavior.These findings provide critical insights into the influence of pressure on glassy properties,integrating the distinct features of compressed glasses into a unified theoretical framework.展开更多
As the mine depth around the world increases,the temperature of the surrounding rock of the mining workface increases significantly.To control the heat hazards,the hot water in the mining floor is developed during min...As the mine depth around the world increases,the temperature of the surrounding rock of the mining workface increases significantly.To control the heat hazards,the hot water in the mining floor is developed during mining to decrease the min-ing workface temperature while also developing geothermal energy.This method is called the co-exploitation of mine and geothermal energy(CMGE).The geothermal development may precipitate the large-scale failure of the nearby fault zone during the mining process.However,the evolution of shear slide and shear failure of fault under geothermal production/rein-jection during mining is missing.Therefore,a fully-coupled hydraulic mechanism(HM)double-medium model for CMGE was developed based on the measured data of the Chensilou mine.A comparative analysis of the mechanical response of fault between CMGE and single mining was conducted.The disturbance of geothermal production pressure and reinjection pressure under mining on fault stability were respectively expounded.The results indicate that:(1)The disturbance of geo-thermal reinjection amplifies the disturbance of mining on fault stability.The amplified effect resulted in a normal stress drop of the fault,further leading to a substantial increase in shear slide distance,failure area,and cumulative seismic moment of fault compared with the single mining process.(2)As the distance of reinjection well to the fault decreases,the fault failure intensity increases.Setting the production well within the fault is advantageous for controlling fault stability under CMGE.(3)The essence of the combined disturbance of CMGE on the nearby fault is the overlay of tensile stress disturbance on the fault rock mass of the mining and geothermal reinjection.Though the geothermal reinjection causes a minor normal stress drop of fault,it can result in a more serious fault failure under CMGE.This paper supplies a significant gap in understanding thenearby faults failure under CMGE.展开更多
The microstructural characterization,corrosion behavior and tensile properties of the extruded lean Mg−1Bi−0.5Sn−0.5In(wt.%)alloy were investigated through scanning electron microscopy(SEM),electron backscatter diffra...The microstructural characterization,corrosion behavior and tensile properties of the extruded lean Mg−1Bi−0.5Sn−0.5In(wt.%)alloy were investigated through scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),X-ray photoelectron spectroscopy(XPS),electrochemical measurements and tensile tests.The results reveal that a microstructure consisting of dynamically recrystallized and deformed grains is obtained.Notably,the investigated alloy exhibits excellent strength−ductility synergy,with tensile yield strength(TYS),ultimate tensile strength(UTS)and elongation(EL)of 254.8 MPa,315.4 MPa,and 25.3%,respectively.Furthermore,in 3.5 wt.%NaCl solution,with the increase of immersion time,the dominant corrosion mechanism of the studied alloy transforms from pitting corrosion to filiform corrosion.After the immersion for 24 h,a composite oxide film(SnO2−Bi2O3−In2O3)is formed,which delays the corrosion process,and the corrosion rate(PH=1.53 mm/a)is finally stabilized.展开更多
The undrained mechanical behavior of unsaturated completely weathered granite(CWG)is highly susceptible to alterations in the hydraulic environment,particularly under uniaxial loading conditions,due to the unique natu...The undrained mechanical behavior of unsaturated completely weathered granite(CWG)is highly susceptible to alterations in the hydraulic environment,particularly under uniaxial loading conditions,due to the unique nature of this soil type.In this study,a series of unconfined compression tests were carried out on unsaturated CWG soil in an underground engineering site,and the effects of varying the environmental variables on the main undrained mechanical properties were analyzed.Based on the experimental results,a novel constitutive model was then established using the damage mechanics theory and the undetermined coefficient method.The results demonstrate that the curves of remolded CWG specimens with different moisture contents and dry densities exhibited diverse characteristics,including brittleness,significant softening,and ductility.As a typical indicator,the unconfined compression strength of soil specimens initially increased with an increase in moisture content and then decreased.Meanwhile,an optimal moisture content of approximately 10.5%could be observed,while a critical moisture content value of 13.0%was identified,beyond which the strength of the specimen decreases sharply.Moreover,the deformation and fracture of CWG specimens were predominantly caused by shear failure,and the ultimate failure modes were primarily influenced by moisture content rather than dry density.Furthermore,by comparing several similar models and the experimental data,the proposed model could accurately replicate the undrained mechanical characteristics of unsaturated CWG soil,and quantitatively describe the key mechanical indexes.These findings offer a valuable reference point for understanding the underlying mechanisms,anticipating potential risks,and implementing effective control measures in similar underground engineering projects.展开更多
A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states...A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states.The experimental results indicate that the dip angle of structural plane(θ)and the intermediate principal stress(σ2)have an important influence on the peak strength,cracking mode,and rockburst severity.The peak strength exhibits a first increase and then decrease as a function ofσ2 for a constantθ.However,whenσ2 is constant,the maximum peak strength is obtained atθof 90°,and the minimum peak strength is obtained atθof 30°or 45°.For the case of an inclined structural plane,the crack type at the tips of structural plane transforms from a mix of wing and anti-wing cracks to wing cracks with an increase inσ2,while the crack type around the tips of structural plane is always anti-wing cracks for the vertical structural plane,accompanied by a series of tensile cracks besides.The specimens with structural plane do not undergo slabbing failure regardless ofθ,and always exhibit composite tensile-shear failure whatever theσ2 value is.With an increase inσ2 andθ,the intensity of the rockburst is consistent with the tendency of the peak strength.By analyzing the relationship between the cohesion(c),internal friction angle(φ),andθin sandstone specimens,we incorporateθinto the true triaxial unloading strength criterion,and propose a modified linear Mogi-Coulomb criterion.Moreover,the crack propagation mechanism at the tips of structural plane,and closure degree of the structural plane under true triaxial unloading conditions are also discussed and summarized.This study provides theoretical guidance for stability assessment of surrounding rocks containing geological structures in deep complex stress environments.展开更多
The fracture mechanisms of coarse-grained heat-affected zone(CGHAZ)for Mg and Mg–Ca deoxidized high-strength low-alloy(HSLA)steels after high heat input welding(HHIW)were investigated based on the microstructures,cra...The fracture mechanisms of coarse-grained heat-affected zone(CGHAZ)for Mg and Mg–Ca deoxidized high-strength low-alloy(HSLA)steels after high heat input welding(HHIW)were investigated based on the microstructures,crack behaviors and mechanical properties.Compared to Mg–Ca steel,the proportion of intergranular acicular ferrites(IAFs)and polygonal ferrites(PFs)in Mg steel increases from 59.97%to 90.16%.The high-angle grain boundaries(HAGBs)and geometrically necessary dislocations density increase from 55.5%and 4.30×10^(14) m^(-2)to 70.4%and 5.48×10^(14) m^(–2),respectively,while effective grain size decreases from 9.46 to 8.12μm.The area fraction of radial zone in Mg steel decreases from 80.8%to 37.7%and cleavage plane is smaller with more curved and finer tearing ridges.The inclusions distributed at the center of cleavage planes and along river lines can serve as crack initiation sites.The zigzag pattern of primary crack propagation path has width of 476μm and the length of secondary cracks remains below 10μm.These cracks are deflected or arrested by IAFs,PFs and HAGBs,and tend to propagate along{110}plane family.These factors contribute to superior overall mechanical properties of Mg steel,especially increasing low-temperature impact toughness from 23 to 175 J.展开更多
The reservoir landslide undergoes periodic saturation-drying cycles affected by reservoir fluctuation in hydropower project area,leading to the irreversible impact on the landslide materials.Sliding zone is the sheari...The reservoir landslide undergoes periodic saturation-drying cycles affected by reservoir fluctuation in hydropower project area,leading to the irreversible impact on the landslide materials.Sliding zone is the shearing part in formation of landslide and controls the further development of landslide.The mechanical behavior of sliding zone soil under compression is a crucial factor in the stability analysis in landslides.In this paper,the sliding zone soil from a giant landslide in the biggest hydropower project area,Three Gorges Reservoir Area,is taken as the research case.The particlesize distribution of the sliding zone soil from this landslide is studied and fractal dimension is adopted as representation.Periodic saturation-drying is introduced as the affecting factor on sliding zone soil properties.The triaxial compression test is conducted to reveal the mechanical behavior of the soil,including stress-strain behavior,elastic modulus,failure stress and strength parameters.These behavior of sliding zone soils with different fractal dimensions are studied under the effects of periodic saturation-drying cycles.The normalized stress-strain curves are displayed for further calculation.The data considering saturation-drying cycles are obtained and compared with the experimental results.展开更多
Smart materials,especially shape memory composites and 4D printing materials,are widely used in aerospace.Deflectors are essential equipment in wind tunnel construction.Classical deflectors are made of metal materials...Smart materials,especially shape memory composites and 4D printing materials,are widely used in aerospace.Deflectors are essential equipment in wind tunnel construction.Classical deflectors are made of metal materials and have a relatively high structural weight.The deflector made of smart material has the advantage of being lighter in weight compared to classical structure,and it could change the bending angle of the deflector structure under external excitation.In this study,the corresponding mechanical property test and finite element simulation of the smart material are carried out,and the deflector made of smart material is further studied and analyzed.Maxwell viscoelasticity model for the material is established,and relevant parameters are obtained through stress relaxation test fitting.According to relevant parameters and literature,finite element simulation of intelligent deflector structure is carried out.The pressure loss coefficient,airflow deflection angle,and velocity uniformity are studied.The numerical model of the minimum pressure loss coefficient is established with reference to the relevant data,and the formula for calculating the optimal upwind radius of the deflector is obtained.Combined with the numerical simulation results of the flow deflection angle and velocity uniformity of the flow field,it provides a reference for the selection of the size of the deflector.展开更多
Exploring dynamic mechanical responses and failure behaviors of hot dry rock(HDR)is significant for geothermal exploitation and stability assessment.In this study,via the split Hopkinson pressure bar(SHPB)system,a ser...Exploring dynamic mechanical responses and failure behaviors of hot dry rock(HDR)is significant for geothermal exploitation and stability assessment.In this study,via the split Hopkinson pressure bar(SHPB)system,a series of dynamic compression tests were conducted on granite treated by cyclic thermal shocks at different temperatures.We analyzed the effects of cyclic thermal shock on the thermal-related physical and dynamic mechanical behaviors of granite.Specifically,the P-wave velocity,dynamic strength,and elastic modulus of the tested granite decrease with increasing temperature and cycle number,while porosity and peak strain increase.The degradation law of dynamic mechanical properties could be described by a cubic polynomial.Cyclic thermal shock promotes shear cracks propagation,causing dynamic failure mode of granite to transition from splitting to tensile-shear composite failure,accompanied by surface spalling and debris splashing.Moreover,the thermal shock damage evolution and coupled failure mechanism of tested granite are discussed.The evolution of thermal shock damage with thermal shock cycle numbers shows an obvious S-shaped surface,featured by an exponential correlation with dynamic mechanical parameters.In addition,with increasing thermal shock temperature and cycles,granite mineral species barely change,but the length and width of thermal cracks increase significantly.The non-uniform expansion of minerals,thermal shock-induced cracking,and water-rock interaction are primary factors for deteriorating dynamic mechanical properties of granite under cyclic thermal shock.展开更多
Developing cost-efective and high-performance magnesium alloys is a key focus in lightweight materials applications.In this work,a Mg extrusion alloy with a remarkable cost-performance advantage was prepared by microa...Developing cost-efective and high-performance magnesium alloys is a key focus in lightweight materials applications.In this work,a Mg extrusion alloy with a remarkable cost-performance advantage was prepared by microalloying with costefective zirconium and adjusting the deformation temperature.Investigations revealed that both the degree of dynamic recrystallization(DRX)and the average grain size increased with increasing extrusion temperature,developing a more homogeneous microstructure.Although all samples exhibited a typical basal texture,a progressive spreading of crystallographic orientations along the<10–10>–<11–20>arc became increasingly pronounced with elevated extrusion temperatures.At a low extrusion temperature of 200℃,the heterogeneous microstructure and strong basal texture favored texture and grain boundary strengthening,resulting in the largest yield strength of~244 MPa.However,the potential diference between coarse and fne grains aggravated localized corrosion with a higher corrosion rate of~14.56 mm/y.Conversely,at a high extrusion temperature of 320℃,the coarse grains and weak basal texture enhanced dislocation storage and the activation of multiple slip systems during axial tension,providing better strain hardening ability and the largest ductility of~13.6%.Nevertheless,grain coarsening and texture weakening were detrimental to mechanical strength(~162 MPa).Interestingly,extrusion at 250℃ developed a good combination of grain size,microstructure homogeneity,and texture intensity,achieving synergistic enhancement in grain boundary strengthening,dislocation storage,and uniform corrosion.Thus,a balanced yield strength of~185 MPa,ductility of~12.9%,and corrosion rate of~4.31 mm/y were obtained in this sample.展开更多
In this work,through performing microstructural characterization,tensile testing and failure analysis,the influence of electrochemical hydrogen charging on the microstructure and mechanical behavior of an as-cast Mg-8...In this work,through performing microstructural characterization,tensile testing and failure analysis,the influence of electrochemical hydrogen charging on the microstructure and mechanical behavior of an as-cast Mg-8wt.%Li alloy was investigated.It revealed that after being hydrogen charged at 50 mA/cm2 for respectively 3 h,6 h and 18 h in 0.1 M NaCl solution,obvious HID occurred and the damage degree was gradually increased with the hydrogen charging time.For the sample being hydrogen charged for 3 h,micro pores with the diameter ranging from 10~30µm were formed and preferentially present inα-Mg phase.Moreover,micro cracks with the length ranging from 10~50µm mainly initiated inα-Mg phase,atα-Mg/β-Li interfaces and the peripheries of pores.With the increase of hydrogen charging time,the numbers of pores and cracks were obviously increased.Tensile results revealed that the hydrogen charging can simultaneously decrease the tensile strength and ductility of the alloy.Compared with the uncharged sample,the tensile yield strength,ultimate tensile strength and the elongation ratio to failure were respectively reduced by 5.7%,7.3%,31.7%for the 3h-charged sample and 24.6%,24.8%,67.0%for the 18h-charged sample.Failure analysis indicated that hydrogen charging can induce the brittle cracking of the alloy and the size of brittle cracking region being composed of quasi-cleavage facets and interfacial cracks on the fracture surfaces was increased with the hydrogen charging time.展开更多
The influence of alloying dysprosium(Dy)element on the biodegradable behavior and mechanical prop-erty of Mg-6 Zn alloys in a simulated body solution(SBF)solution was studied.The results indicate that Dy significantly...The influence of alloying dysprosium(Dy)element on the biodegradable behavior and mechanical prop-erty of Mg-6 Zn alloys in a simulated body solution(SBF)solution was studied.The results indicate that Dy significantly contributes to grain refinement,and form a distinctive fiber texture in Dy-containing al-loys.The presence of Dy promotes the formation of granular DyZn3 precipitates,which possess a higher electrode potential than the matrix,thus accelerating matrix corrosion.Corrosion results demonstrate that the Dy element is not beneficial to reducing the initial corrosion rate of Mg-6 Zn but is conducive to improving the protective effect of product film as the immersion time increases.Dy-containing alloys exhibit higher strength than Mg-6 Zn while maintaining good plasticity related to grain boundary and precipitation strength effects.Consequently,the incorporation of 2 wt.%Dy into Mg-6 Zn alloys results in a synergistic enhancement of strength,as well as moderate corrosion resistance and fracture elongation.展开更多
The effects of Zr addition on the mechanical properties and in vitro degradation behavior of Mg-1.0Yb-xZr(x=0,0.2,1.0,and 1.53,wt.%)cast alloys were investigated.The results indicated that with increasing Zr addition,...The effects of Zr addition on the mechanical properties and in vitro degradation behavior of Mg-1.0Yb-xZr(x=0,0.2,1.0,and 1.53,wt.%)cast alloys were investigated.The results indicated that with increasing Zr addition,a much refined and homogeneous equiaxed grain structure was achieved from a typical columnar grain structure,in companion with the appearance and coarsening of Zr-rich particles.Subsequent electrochemical and immersion tests demonstrated that the corrosion of the alloy was Zr-addition dependent.A trace or excessive Zr addition caused severe localized corrosion attacks,whereas Zr-free and 1.0 Zr alloyed counterparts were generally corroded uniformly.The good combination of mechanical properties and corrosion resistance of the Mg-1.0Yb-1.0Zr alloy was resulted from the refined and homogeneous equiaxed grain structure and fine dispersed Zr-rich particles,thus improving the comprehensive mechanical properties by grain refinement and reducing corrosion rate by generating a more stable and compact passivation layer during long-term immersion.展开更多
Additive manufactured Mg-RE alloys usually show exceptional mechanical properties,which is mainly attributed to their refined grains in previous studies.Since Mg-RE series are typical age-hardenable alloys,this study ...Additive manufactured Mg-RE alloys usually show exceptional mechanical properties,which is mainly attributed to their refined grains in previous studies.Since Mg-RE series are typical age-hardenable alloys,this study focuses on the aging behavior of wire arc additive manufactured Mg-9Gd-3Y-0.5Zr(GW93K)alloy and compares it with the as-cast counterpart,providing a new insight into the strengthening mechanism of additive manufactured alloys.It was revealed that both the refined equiaxedα-Mg grains and small-sized(only 5~10 nm)β′precipitates with an extremely high number density(~2.53×10^(4)µm^(-2))should be considered for the strengthening mechanisms of the deposited alloy.The promoted precipitation behavior is facilitated by the dislocation pile-ups formed under multiple thermal cycles and a high cooling rate during deposition.As a result,the deposited alloy at peak-aged state exhibits better comprehensive properties of UTS=392 MPa and EL=3.3%,which is 19%and 18%higher than that of the cast sample,individually.展开更多
A systematic study was conducted on the microstructure,mechanical properties,and corrosion resistance of Ti-20Zr-xAl-2.5Sn(x=5,7,9,11,and 13 wt.%)quaternary alloy.The microstructure of the rolled alloys was characteri...A systematic study was conducted on the microstructure,mechanical properties,and corrosion resistance of Ti-20Zr-xAl-2.5Sn(x=5,7,9,11,and 13 wt.%)quaternary alloy.The microstructure of the rolled alloys was characterized by optical microscopy,X-ray diffraction,scanning electron microscopy,and transmission electron microscopy.The mechanical properties were analyzed through tensile tests,microhardness tests,and friction wear tests.Corrosion performance was evaluated using electrochemical tests,and X-ray photoelectron spectroscopy was employed to analyze the passivation film on the alloy surface.The results show that increasing Al content improves the mechanical properties of the alloy,but excessive Al leads to the creation of Ti_(3)Al,resulting in a substantial deterioration of the mechanical characteristics of the alloy.The alloy with 7 wt.%Al exhibited the best overall mechanical properties.Electrochemical experiments revealed that higher Al content positively affected the corrosion resistance,with the alloy containing 7 wt.%Al showing the best corrosion resistance,followed by a slight decline.A small amount of Al_(2)O_(3)in the passivation film enhanced the corrosion resistance,but the formation of Al_(2)O_(3)with higher Al content decreased the corrosion performance.展开更多
This study develops novel Mg-Sn-In-Ga alloys as potential implant materials for orthopedic applications.The corrosion behavior of the Mg-Sn-In-Ga alloys was studied through mass loss measurements,hydrogen evolution me...This study develops novel Mg-Sn-In-Ga alloys as potential implant materials for orthopedic applications.The corrosion behavior of the Mg-Sn-In-Ga alloys was studied through mass loss measurements,hydrogen evolution measurements,electrochemical analysis,and corrosion morphology observations.The results show that the corrosion rate of the Mg-1Sn-1In-1Ga alloy was only 0.10±0.003 mm/y after immersion in Hank’s solution for 15 days.This outstanding corrosion resistance was associated with the protective efect of the corrosion products.The increase in the Sn and Ga element content led to the precipitation of a large amount of Mg_(2)Sn and Mg_(5)Ga_(2),which had a dominant efect on the corrosion rate in the Mg-5Sn-1In-2Ga alloy.These precipitates increased the current density and detached from the alloy surface during the corrosion process.This can lead to a weakened protective efect of the corrosion layer,and thus generate localized corrosion and an increase in the corrosion rate.The strength of the Mg-5Sn-1In-2Ga alloy was enhanced due to fne-grain strengthening and precipitation strengthening.The ultimate tensile strength and yield strength of the Mg-5Sn-1In-2Ga alloy were~309 MPa and~253 MPa,respectively.展开更多
Zinc(Zn)-based materials show broad application prospects for bone repair due to their biodegradability and good biocompatibility.In particular,Zn metal foam has unique interconnected pore structure that facilitates i...Zinc(Zn)-based materials show broad application prospects for bone repair due to their biodegradability and good biocompatibility.In particular,Zn metal foam has unique interconnected pore structure that facilitates inward growth of new bone tissue,making it ideal candidates for orthopedic implants.However,pure Zn metal foam shows poor mechanical property,high degradation rate,and unsatisfactory osteogenic activity.Herein,Zinc-manganese(Zn-Mn)alloy foams were electrodeposited in Zn and Mn-containing electrolytes to overcome the concerns.The results showed that Mn could be incorporated into the foams in the form of MnZn_(13).Zn-Mn alloy foams showed better mechanical property and osteogenic activity as well as moderate degradation rate when compared with pure Zn metal foam.In addition,these properties could also be regulated by preparation process.The peak stress and osteogenic activity increased with deposition current(0.3‒0.5 A)and electrolyte pH(3‒5),but decreased with electrolyte temperature(20‒40℃),while the degradation rate exhibited opposite tendency,which suggests high deposition current and electrolyte pH and low electrolyte temperature can fabricate Zn-Mn alloy foam with favorable mechanical property,moderate degradation rate,and osteogenic activity.These findings provide a valuable reference for the design and fabrication of novel Zn-based biodegradable materials.展开更多
Ti-Gd alloys with Gd contents of 2 wt%-8 wt% were prepared,and the influence of Gd content on the microstructure,mechanical properties,corrosion behavior,neutron absorption property and density of the alloy weas inves...Ti-Gd alloys with Gd contents of 2 wt%-8 wt% were prepared,and the influence of Gd content on the microstructure,mechanical properties,corrosion behavior,neutron absorption property and density of the alloy weas investigated.The micro structure changes from full lamellar α phase to fine equiaxed crystals,and the area fraction of Gd-rich phase decreases from 3.2% to 1.8% and then increases to 9.1%.Gd has three existing forms:pure Gd,compound oxide of Gd_(2)TiO_(5)and/or Gd_(2)O_(3)and solidifies in the Ti matrix.Ti-4Gd exhibits the best mechanical properties,its tensile strength and elongation is 102 MPa and 49%,respectively.The neutron transmittancy of Ti-8Gd alloy in water is the lowest,which is 3.75%.The corrosion rate of Ti-Gd alloy is 0.00097-0.00238 mm/a,which meets the corrosion standard of small-scale nuclear reactors and containers for spent fuel.展开更多
High temperature and high stress are critical challenges facing enhanced geothermal systems(EGS).This study investigates the physical and mechanical behavior and acoustic emission(AE)characteristics of granite subject...High temperature and high stress are critical challenges facing enhanced geothermal systems(EGS).This study investigates the physical and mechanical behavior and acoustic emission(AE)characteristics of granite subjected to heating–water cooling treatments at temperatures ranging from 25℃ to 400℃.Changes in physical properties,including volume expansion,mass loss,and P-wave velocity,were examined to quantify the extent of thermal damage.Results show that visible surface cracking occurs on granite samples treated above 300℃,with P-wave velocity being the most sensitive indicator of thermal damage.Uniaxial and triaxial compression tests were conducted to explore the effects of temperature and confining pressure on granite’s strength,deformation,failure modes,energy evolution,and brittleness.While peak strength remains largely unaffected by temperature,failure modes transition from axial splitting to shear as confining pressure increases.Thermal damage reduces the rock’s energy storage capacity and increases energy dissipation during loading.The brittleness index decreases with temperature and confining pressure,though granite still exhibits pronounced brittle behavior within the studied range.Distinct differences were observed in the AE temporal characteristics and energy evolution of granite samples under uniaxial and triaxial compression conditions.As the specimen approaches failure,the abrupt increase in AE hit rate occurs earlier than the corresponding rise in AE energy.The global b-value of the granite samples increased with treatment temperature,and the global b-value in triaxial compression tests was higher than that in uniaxial compression tests.The evolution of timedependent b-value also varied with increasing confining pressure.These findings,particularly the AE temporal characteristics and distinct b-value evolution under confinement of thermally damaged granite,provide important implications for microseismic-based stability assessment and early warning in thermally damaged rock masses.展开更多
Basalt fibers/7075 aluminum matrix composites were studied to meet the demand of aluminum alloy drill pipes for material wear resistance.The composites with different basalt fiber additions were prepared by hot presse...Basalt fibers/7075 aluminum matrix composites were studied to meet the demand of aluminum alloy drill pipes for material wear resistance.The composites with different basalt fiber additions were prepared by hot pressed sintering and hot extrusion.The mechanical properties as well as friction and wear properties of the composites were studied by microstructure analysis,tensile experiments,friction and wear experiments.The results showed that basalt fibers were oriented and uniformly distributed and led to local grain refinement in the alloy matrix.The hardness and elongation of the composites were improved.The friction coefficient of the composites increased and then decreased,and the maximum wear depth and wear amount decreased,then increased,then decreased again with the growth of basalt fiber addition.Meanwhile,the inclusion of basalt fibers mitigated the uneven wear of the extruded 7075 aluminum alloy.The value of wear depth difference of 7075-0.2BF was the smallest,and that of 7075-2.0BF was close to it.The maximum wear depth and wear volume the 7075-0.2BF and 7075-2.0BF were also the smallest.The inhibition of uneven wear by basalt fibers enhanced of wear resistance for 7075 aluminum alloy,which has reference significance for improving the performance of aluminum alloy drill pipes.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.T2325004 and 52161160330)the National Natural Science Foundation of China (Grants No.12504233)+2 种基金Advanced MaterialsNational Science and Technology Major Project (Grant No.2024ZD0606900)the Talent Hub for “AI+New Materials” Basic Researchthe Key Research and Development Program of Ningbo (Grant No.2025Z088)。
文摘The functional properties of glasses are governed by their formation history and the complex relaxation processes they undergo.However,under extreme conditions,glass behaviors are still elusive.In this study,we employ simulations with varied protocols to evaluate the effectiveness of different descriptors in predicting mechanical properties across both low-and high-pressure regimes.Our findings demonstrate that conventional structural and configurational descriptors fail to correlate with the mechanical response following pressure release,whereas the activation energy descriptor exhibits robust linearity with shear modulus after correcting for pressure effects.Notably,the soft mode parameter emerges as an ideal and computationally efficient alternative for capturing this mechanical behavior.These findings provide critical insights into the influence of pressure on glassy properties,integrating the distinct features of compressed glasses into a unified theoretical framework.
基金supported by the Key Project of the National Natural Science Foundation of China(U23B2091)the National Key R&D Program of China(2022YFC2905600)+1 种基金the Youth Project of the National Natural Science Foundation of China(52304104 and 52404157)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(GZB20240825).
文摘As the mine depth around the world increases,the temperature of the surrounding rock of the mining workface increases significantly.To control the heat hazards,the hot water in the mining floor is developed during mining to decrease the min-ing workface temperature while also developing geothermal energy.This method is called the co-exploitation of mine and geothermal energy(CMGE).The geothermal development may precipitate the large-scale failure of the nearby fault zone during the mining process.However,the evolution of shear slide and shear failure of fault under geothermal production/rein-jection during mining is missing.Therefore,a fully-coupled hydraulic mechanism(HM)double-medium model for CMGE was developed based on the measured data of the Chensilou mine.A comparative analysis of the mechanical response of fault between CMGE and single mining was conducted.The disturbance of geothermal production pressure and reinjection pressure under mining on fault stability were respectively expounded.The results indicate that:(1)The disturbance of geo-thermal reinjection amplifies the disturbance of mining on fault stability.The amplified effect resulted in a normal stress drop of the fault,further leading to a substantial increase in shear slide distance,failure area,and cumulative seismic moment of fault compared with the single mining process.(2)As the distance of reinjection well to the fault decreases,the fault failure intensity increases.Setting the production well within the fault is advantageous for controlling fault stability under CMGE.(3)The essence of the combined disturbance of CMGE on the nearby fault is the overlay of tensile stress disturbance on the fault rock mass of the mining and geothermal reinjection.Though the geothermal reinjection causes a minor normal stress drop of fault,it can result in a more serious fault failure under CMGE.This paper supplies a significant gap in understanding thenearby faults failure under CMGE.
基金supported by the National Natural Science Foundation of China(No.51901153)the Natural Science Foundation of Shanxi,China(No.202103021224049)+1 种基金the Shanxi Zhejiang University New Materials and Chemical Research Institute Scientific Research Project,China(No.2022SX-TD025)the Open Project of Salt Lake Chemical Engineering Research Complex,Qinghai University,China(No.2023-DXSSKF-Z02).
文摘The microstructural characterization,corrosion behavior and tensile properties of the extruded lean Mg−1Bi−0.5Sn−0.5In(wt.%)alloy were investigated through scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),X-ray photoelectron spectroscopy(XPS),electrochemical measurements and tensile tests.The results reveal that a microstructure consisting of dynamically recrystallized and deformed grains is obtained.Notably,the investigated alloy exhibits excellent strength−ductility synergy,with tensile yield strength(TYS),ultimate tensile strength(UTS)and elongation(EL)of 254.8 MPa,315.4 MPa,and 25.3%,respectively.Furthermore,in 3.5 wt.%NaCl solution,with the increase of immersion time,the dominant corrosion mechanism of the studied alloy transforms from pitting corrosion to filiform corrosion.After the immersion for 24 h,a composite oxide film(SnO2−Bi2O3−In2O3)is formed,which delays the corrosion process,and the corrosion rate(PH=1.53 mm/a)is finally stabilized.
基金Project(42202318)supported by the National Natural Science Foundation of ChinaProject(252300421199)supported by the Natural Science Foundation of Henan Province,ChinaProject(2024JJ6219)supported by the Hunan Provincial Natural Science Foundation of China。
文摘The undrained mechanical behavior of unsaturated completely weathered granite(CWG)is highly susceptible to alterations in the hydraulic environment,particularly under uniaxial loading conditions,due to the unique nature of this soil type.In this study,a series of unconfined compression tests were carried out on unsaturated CWG soil in an underground engineering site,and the effects of varying the environmental variables on the main undrained mechanical properties were analyzed.Based on the experimental results,a novel constitutive model was then established using the damage mechanics theory and the undetermined coefficient method.The results demonstrate that the curves of remolded CWG specimens with different moisture contents and dry densities exhibited diverse characteristics,including brittleness,significant softening,and ductility.As a typical indicator,the unconfined compression strength of soil specimens initially increased with an increase in moisture content and then decreased.Meanwhile,an optimal moisture content of approximately 10.5%could be observed,while a critical moisture content value of 13.0%was identified,beyond which the strength of the specimen decreases sharply.Moreover,the deformation and fracture of CWG specimens were predominantly caused by shear failure,and the ultimate failure modes were primarily influenced by moisture content rather than dry density.Furthermore,by comparing several similar models and the experimental data,the proposed model could accurately replicate the undrained mechanical characteristics of unsaturated CWG soil,and quantitatively describe the key mechanical indexes.These findings offer a valuable reference point for understanding the underlying mechanisms,anticipating potential risks,and implementing effective control measures in similar underground engineering projects.
基金supports from the National Natural Science Foundation of China (Grant Nos.52004143 and 52374095)the open fund for the Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines (Grant No.SKLMRDPC21KF06).
文摘A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states.The experimental results indicate that the dip angle of structural plane(θ)and the intermediate principal stress(σ2)have an important influence on the peak strength,cracking mode,and rockburst severity.The peak strength exhibits a first increase and then decrease as a function ofσ2 for a constantθ.However,whenσ2 is constant,the maximum peak strength is obtained atθof 90°,and the minimum peak strength is obtained atθof 30°or 45°.For the case of an inclined structural plane,the crack type at the tips of structural plane transforms from a mix of wing and anti-wing cracks to wing cracks with an increase inσ2,while the crack type around the tips of structural plane is always anti-wing cracks for the vertical structural plane,accompanied by a series of tensile cracks besides.The specimens with structural plane do not undergo slabbing failure regardless ofθ,and always exhibit composite tensile-shear failure whatever theσ2 value is.With an increase inσ2 andθ,the intensity of the rockburst is consistent with the tendency of the peak strength.By analyzing the relationship between the cohesion(c),internal friction angle(φ),andθin sandstone specimens,we incorporateθinto the true triaxial unloading strength criterion,and propose a modified linear Mogi-Coulomb criterion.Moreover,the crack propagation mechanism at the tips of structural plane,and closure degree of the structural plane under true triaxial unloading conditions are also discussed and summarized.This study provides theoretical guidance for stability assessment of surrounding rocks containing geological structures in deep complex stress environments.
基金financial support by the National Natural Science Foundation of China(No.52474361)the Independent Research Project of State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University(No.SKLASS 2023-Z01)the Science and Technology Commission of Shanghai Municipality(No.19DZ2270200).
文摘The fracture mechanisms of coarse-grained heat-affected zone(CGHAZ)for Mg and Mg–Ca deoxidized high-strength low-alloy(HSLA)steels after high heat input welding(HHIW)were investigated based on the microstructures,crack behaviors and mechanical properties.Compared to Mg–Ca steel,the proportion of intergranular acicular ferrites(IAFs)and polygonal ferrites(PFs)in Mg steel increases from 59.97%to 90.16%.The high-angle grain boundaries(HAGBs)and geometrically necessary dislocations density increase from 55.5%and 4.30×10^(14) m^(-2)to 70.4%and 5.48×10^(14) m^(–2),respectively,while effective grain size decreases from 9.46 to 8.12μm.The area fraction of radial zone in Mg steel decreases from 80.8%to 37.7%and cleavage plane is smaller with more curved and finer tearing ridges.The inclusions distributed at the center of cleavage planes and along river lines can serve as crack initiation sites.The zigzag pattern of primary crack propagation path has width of 476μm and the length of secondary cracks remains below 10μm.These cracks are deflected or arrested by IAFs,PFs and HAGBs,and tend to propagate along{110}plane family.These factors contribute to superior overall mechanical properties of Mg steel,especially increasing low-temperature impact toughness from 23 to 175 J.
基金financially supported by the National Natural Science Foundation of China(Nos.42107194,42090054,42377182)the Fundamental Research Funds for the Central Universities(No.CUGL190810)the Open Foundation of Engineering Research Center of Rock-Soil Drilling&Excavation and Protection,Ministry of Education(No.201802)。
文摘The reservoir landslide undergoes periodic saturation-drying cycles affected by reservoir fluctuation in hydropower project area,leading to the irreversible impact on the landslide materials.Sliding zone is the shearing part in formation of landslide and controls the further development of landslide.The mechanical behavior of sliding zone soil under compression is a crucial factor in the stability analysis in landslides.In this paper,the sliding zone soil from a giant landslide in the biggest hydropower project area,Three Gorges Reservoir Area,is taken as the research case.The particlesize distribution of the sliding zone soil from this landslide is studied and fractal dimension is adopted as representation.Periodic saturation-drying is introduced as the affecting factor on sliding zone soil properties.The triaxial compression test is conducted to reveal the mechanical behavior of the soil,including stress-strain behavior,elastic modulus,failure stress and strength parameters.These behavior of sliding zone soils with different fractal dimensions are studied under the effects of periodic saturation-drying cycles.The normalized stress-strain curves are displayed for further calculation.The data considering saturation-drying cycles are obtained and compared with the experimental results.
文摘Smart materials,especially shape memory composites and 4D printing materials,are widely used in aerospace.Deflectors are essential equipment in wind tunnel construction.Classical deflectors are made of metal materials and have a relatively high structural weight.The deflector made of smart material has the advantage of being lighter in weight compared to classical structure,and it could change the bending angle of the deflector structure under external excitation.In this study,the corresponding mechanical property test and finite element simulation of the smart material are carried out,and the deflector made of smart material is further studied and analyzed.Maxwell viscoelasticity model for the material is established,and relevant parameters are obtained through stress relaxation test fitting.According to relevant parameters and literature,finite element simulation of intelligent deflector structure is carried out.The pressure loss coefficient,airflow deflection angle,and velocity uniformity are studied.The numerical model of the minimum pressure loss coefficient is established with reference to the relevant data,and the formula for calculating the optimal upwind radius of the deflector is obtained.Combined with the numerical simulation results of the flow deflection angle and velocity uniformity of the flow field,it provides a reference for the selection of the size of the deflector.
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(Grant Nos.52225904 and 52039007)the Natural Science Foundation of Sichuan Province(Grant No.2023NSFSC0377)supported by the New Cornerstone Science Foundation through the XPLORER PRIZE.
文摘Exploring dynamic mechanical responses and failure behaviors of hot dry rock(HDR)is significant for geothermal exploitation and stability assessment.In this study,via the split Hopkinson pressure bar(SHPB)system,a series of dynamic compression tests were conducted on granite treated by cyclic thermal shocks at different temperatures.We analyzed the effects of cyclic thermal shock on the thermal-related physical and dynamic mechanical behaviors of granite.Specifically,the P-wave velocity,dynamic strength,and elastic modulus of the tested granite decrease with increasing temperature and cycle number,while porosity and peak strain increase.The degradation law of dynamic mechanical properties could be described by a cubic polynomial.Cyclic thermal shock promotes shear cracks propagation,causing dynamic failure mode of granite to transition from splitting to tensile-shear composite failure,accompanied by surface spalling and debris splashing.Moreover,the thermal shock damage evolution and coupled failure mechanism of tested granite are discussed.The evolution of thermal shock damage with thermal shock cycle numbers shows an obvious S-shaped surface,featured by an exponential correlation with dynamic mechanical parameters.In addition,with increasing thermal shock temperature and cycles,granite mineral species barely change,but the length and width of thermal cracks increase significantly.The non-uniform expansion of minerals,thermal shock-induced cracking,and water-rock interaction are primary factors for deteriorating dynamic mechanical properties of granite under cyclic thermal shock.
基金supported by the Natural Science Foundation Project of CQ CSTC(Grant Nos.CSTB2024NSCQ-MSX0473 and CSTC2020JCYJ-MSXMX0170)the National Natural Science Foundation of China(Grant No.51975484)the Research Initiation Project under the Talent Introduction Program at Southwest University(Grant No.SWU-KR24001).
文摘Developing cost-efective and high-performance magnesium alloys is a key focus in lightweight materials applications.In this work,a Mg extrusion alloy with a remarkable cost-performance advantage was prepared by microalloying with costefective zirconium and adjusting the deformation temperature.Investigations revealed that both the degree of dynamic recrystallization(DRX)and the average grain size increased with increasing extrusion temperature,developing a more homogeneous microstructure.Although all samples exhibited a typical basal texture,a progressive spreading of crystallographic orientations along the<10–10>–<11–20>arc became increasingly pronounced with elevated extrusion temperatures.At a low extrusion temperature of 200℃,the heterogeneous microstructure and strong basal texture favored texture and grain boundary strengthening,resulting in the largest yield strength of~244 MPa.However,the potential diference between coarse and fne grains aggravated localized corrosion with a higher corrosion rate of~14.56 mm/y.Conversely,at a high extrusion temperature of 320℃,the coarse grains and weak basal texture enhanced dislocation storage and the activation of multiple slip systems during axial tension,providing better strain hardening ability and the largest ductility of~13.6%.Nevertheless,grain coarsening and texture weakening were detrimental to mechanical strength(~162 MPa).Interestingly,extrusion at 250℃ developed a good combination of grain size,microstructure homogeneity,and texture intensity,achieving synergistic enhancement in grain boundary strengthening,dislocation storage,and uniform corrosion.Thus,a balanced yield strength of~185 MPa,ductility of~12.9%,and corrosion rate of~4.31 mm/y were obtained in this sample.
基金supported by the National Natural Science Foundation of China Projects under grant[nos.U21A2049,52071220,51871211,51701129 and 51971054]Liaoning Province's project of“Revitalizing Liaoning Talents”(XLYC1907062)+6 种基金the Doctor Startup Fund of Natural Science Foundation Program of Liaoning Province(no.2019-BS-200)the Strategic New Industry Development Special Foundation of Shenzhen(JCYJ20170306141749970)the funds of International Joint Laboratory for Light Alloys,Liaoning BaiQianWan Talents Program,the Domain Foundation of Equipment Advance Research of 13th Five-year Plan(61409220118)National Key Research and Development Program of China under grant[nos.2017YFB0702001 and 2016YFB0301105]the Innovation Fund of Institute of Metal Research(IMR),Chinese Academy of Sciences(CAS),the National Basic Research Program of China(973 Program)project under grant no.2013CB632205the Fundamental Research Fund for the Central Universities under grant[no.N2009006]Bintech-IMR R&D Program[no.GYY-JSBU-2022-009].
文摘In this work,through performing microstructural characterization,tensile testing and failure analysis,the influence of electrochemical hydrogen charging on the microstructure and mechanical behavior of an as-cast Mg-8wt.%Li alloy was investigated.It revealed that after being hydrogen charged at 50 mA/cm2 for respectively 3 h,6 h and 18 h in 0.1 M NaCl solution,obvious HID occurred and the damage degree was gradually increased with the hydrogen charging time.For the sample being hydrogen charged for 3 h,micro pores with the diameter ranging from 10~30µm were formed and preferentially present inα-Mg phase.Moreover,micro cracks with the length ranging from 10~50µm mainly initiated inα-Mg phase,atα-Mg/β-Li interfaces and the peripheries of pores.With the increase of hydrogen charging time,the numbers of pores and cracks were obviously increased.Tensile results revealed that the hydrogen charging can simultaneously decrease the tensile strength and ductility of the alloy.Compared with the uncharged sample,the tensile yield strength,ultimate tensile strength and the elongation ratio to failure were respectively reduced by 5.7%,7.3%,31.7%for the 3h-charged sample and 24.6%,24.8%,67.0%for the 18h-charged sample.Failure analysis indicated that hydrogen charging can induce the brittle cracking of the alloy and the size of brittle cracking region being composed of quasi-cleavage facets and interfacial cracks on the fracture surfaces was increased with the hydrogen charging time.
基金supported by the National Natural Science Foundation of China(No.52301133)the China Postdoctoral Science Foundation(No.2023M730276)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(No.YESS20210415).
文摘The influence of alloying dysprosium(Dy)element on the biodegradable behavior and mechanical prop-erty of Mg-6 Zn alloys in a simulated body solution(SBF)solution was studied.The results indicate that Dy significantly contributes to grain refinement,and form a distinctive fiber texture in Dy-containing al-loys.The presence of Dy promotes the formation of granular DyZn3 precipitates,which possess a higher electrode potential than the matrix,thus accelerating matrix corrosion.Corrosion results demonstrate that the Dy element is not beneficial to reducing the initial corrosion rate of Mg-6 Zn but is conducive to improving the protective effect of product film as the immersion time increases.Dy-containing alloys exhibit higher strength than Mg-6 Zn while maintaining good plasticity related to grain boundary and precipitation strength effects.Consequently,the incorporation of 2 wt.%Dy into Mg-6 Zn alloys results in a synergistic enhancement of strength,as well as moderate corrosion resistance and fracture elongation.
基金the financial supports from the China Scholarship Council(No.201808505057)。
文摘The effects of Zr addition on the mechanical properties and in vitro degradation behavior of Mg-1.0Yb-xZr(x=0,0.2,1.0,and 1.53,wt.%)cast alloys were investigated.The results indicated that with increasing Zr addition,a much refined and homogeneous equiaxed grain structure was achieved from a typical columnar grain structure,in companion with the appearance and coarsening of Zr-rich particles.Subsequent electrochemical and immersion tests demonstrated that the corrosion of the alloy was Zr-addition dependent.A trace or excessive Zr addition caused severe localized corrosion attacks,whereas Zr-free and 1.0 Zr alloyed counterparts were generally corroded uniformly.The good combination of mechanical properties and corrosion resistance of the Mg-1.0Yb-1.0Zr alloy was resulted from the refined and homogeneous equiaxed grain structure and fine dispersed Zr-rich particles,thus improving the comprehensive mechanical properties by grain refinement and reducing corrosion rate by generating a more stable and compact passivation layer during long-term immersion.
基金supported by the National Natural Science Foundation of China(Nos.U2037601,U2241231,and 51821001).
文摘Additive manufactured Mg-RE alloys usually show exceptional mechanical properties,which is mainly attributed to their refined grains in previous studies.Since Mg-RE series are typical age-hardenable alloys,this study focuses on the aging behavior of wire arc additive manufactured Mg-9Gd-3Y-0.5Zr(GW93K)alloy and compares it with the as-cast counterpart,providing a new insight into the strengthening mechanism of additive manufactured alloys.It was revealed that both the refined equiaxedα-Mg grains and small-sized(only 5~10 nm)β′precipitates with an extremely high number density(~2.53×10^(4)µm^(-2))should be considered for the strengthening mechanisms of the deposited alloy.The promoted precipitation behavior is facilitated by the dislocation pile-ups formed under multiple thermal cycles and a high cooling rate during deposition.As a result,the deposited alloy at peak-aged state exhibits better comprehensive properties of UTS=392 MPa and EL=3.3%,which is 19%and 18%higher than that of the cast sample,individually.
基金supported by the National Natural Science Foundation of China(Grant Nos.52474406,52405226,and 52071126)the Natural Science Foundation of Hebei Province of China(Grant No.E2024202254)+2 种基金the Natural Science Foundation of Tianjin City China(Grant No.22JCQNJC01240)the Central Guidance on Local Science and Technology Development Fund of Hebei Province(Grant No.226Z1009G)the Special funds for science and technology innovation in Hebei(Grant No.2022X19).
文摘A systematic study was conducted on the microstructure,mechanical properties,and corrosion resistance of Ti-20Zr-xAl-2.5Sn(x=5,7,9,11,and 13 wt.%)quaternary alloy.The microstructure of the rolled alloys was characterized by optical microscopy,X-ray diffraction,scanning electron microscopy,and transmission electron microscopy.The mechanical properties were analyzed through tensile tests,microhardness tests,and friction wear tests.Corrosion performance was evaluated using electrochemical tests,and X-ray photoelectron spectroscopy was employed to analyze the passivation film on the alloy surface.The results show that increasing Al content improves the mechanical properties of the alloy,but excessive Al leads to the creation of Ti_(3)Al,resulting in a substantial deterioration of the mechanical characteristics of the alloy.The alloy with 7 wt.%Al exhibited the best overall mechanical properties.Electrochemical experiments revealed that higher Al content positively affected the corrosion resistance,with the alloy containing 7 wt.%Al showing the best corrosion resistance,followed by a slight decline.A small amount of Al_(2)O_(3)in the passivation film enhanced the corrosion resistance,but the formation of Al_(2)O_(3)with higher Al content decreased the corrosion performance.
基金supported by the National Natural Science Foundation of China(No.52301041)the Guizhou Provincial Basic Research Program(No.QianKeHeJiChu-ZK[2024]YiBan036)+1 种基金the Special Fund for Special Posts of Guizhou University(No.[2023]26)the Fundamental Research Funds for the Central Universities.E.G.thanks support from Xiaomi Foundation.
文摘This study develops novel Mg-Sn-In-Ga alloys as potential implant materials for orthopedic applications.The corrosion behavior of the Mg-Sn-In-Ga alloys was studied through mass loss measurements,hydrogen evolution measurements,electrochemical analysis,and corrosion morphology observations.The results show that the corrosion rate of the Mg-1Sn-1In-1Ga alloy was only 0.10±0.003 mm/y after immersion in Hank’s solution for 15 days.This outstanding corrosion resistance was associated with the protective efect of the corrosion products.The increase in the Sn and Ga element content led to the precipitation of a large amount of Mg_(2)Sn and Mg_(5)Ga_(2),which had a dominant efect on the corrosion rate in the Mg-5Sn-1In-2Ga alloy.These precipitates increased the current density and detached from the alloy surface during the corrosion process.This can lead to a weakened protective efect of the corrosion layer,and thus generate localized corrosion and an increase in the corrosion rate.The strength of the Mg-5Sn-1In-2Ga alloy was enhanced due to fne-grain strengthening and precipitation strengthening.The ultimate tensile strength and yield strength of the Mg-5Sn-1In-2Ga alloy were~309 MPa and~253 MPa,respectively.
基金supported by the Key Research and Development Program of Shanxi Province(202102130501007)the Natural Science Foundation of Shanxi Province(202403021212109,202203021211173)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(2024L039).
文摘Zinc(Zn)-based materials show broad application prospects for bone repair due to their biodegradability and good biocompatibility.In particular,Zn metal foam has unique interconnected pore structure that facilitates inward growth of new bone tissue,making it ideal candidates for orthopedic implants.However,pure Zn metal foam shows poor mechanical property,high degradation rate,and unsatisfactory osteogenic activity.Herein,Zinc-manganese(Zn-Mn)alloy foams were electrodeposited in Zn and Mn-containing electrolytes to overcome the concerns.The results showed that Mn could be incorporated into the foams in the form of MnZn_(13).Zn-Mn alloy foams showed better mechanical property and osteogenic activity as well as moderate degradation rate when compared with pure Zn metal foam.In addition,these properties could also be regulated by preparation process.The peak stress and osteogenic activity increased with deposition current(0.3‒0.5 A)and electrolyte pH(3‒5),but decreased with electrolyte temperature(20‒40℃),while the degradation rate exhibited opposite tendency,which suggests high deposition current and electrolyte pH and low electrolyte temperature can fabricate Zn-Mn alloy foam with favorable mechanical property,moderate degradation rate,and osteogenic activity.These findings provide a valuable reference for the design and fabrication of novel Zn-based biodegradable materials.
基金Project supported by the National Key R&D Program of China (2023YFB3506703)。
文摘Ti-Gd alloys with Gd contents of 2 wt%-8 wt% were prepared,and the influence of Gd content on the microstructure,mechanical properties,corrosion behavior,neutron absorption property and density of the alloy weas investigated.The micro structure changes from full lamellar α phase to fine equiaxed crystals,and the area fraction of Gd-rich phase decreases from 3.2% to 1.8% and then increases to 9.1%.Gd has three existing forms:pure Gd,compound oxide of Gd_(2)TiO_(5)and/or Gd_(2)O_(3)and solidifies in the Ti matrix.Ti-4Gd exhibits the best mechanical properties,its tensile strength and elongation is 102 MPa and 49%,respectively.The neutron transmittancy of Ti-8Gd alloy in water is the lowest,which is 3.75%.The corrosion rate of Ti-Gd alloy is 0.00097-0.00238 mm/a,which meets the corrosion standard of small-scale nuclear reactors and containers for spent fuel.
基金supported by the CHN Energy Investment Group,grant numbers GJNY-23-86 and GJNY-23-92.
文摘High temperature and high stress are critical challenges facing enhanced geothermal systems(EGS).This study investigates the physical and mechanical behavior and acoustic emission(AE)characteristics of granite subjected to heating–water cooling treatments at temperatures ranging from 25℃ to 400℃.Changes in physical properties,including volume expansion,mass loss,and P-wave velocity,were examined to quantify the extent of thermal damage.Results show that visible surface cracking occurs on granite samples treated above 300℃,with P-wave velocity being the most sensitive indicator of thermal damage.Uniaxial and triaxial compression tests were conducted to explore the effects of temperature and confining pressure on granite’s strength,deformation,failure modes,energy evolution,and brittleness.While peak strength remains largely unaffected by temperature,failure modes transition from axial splitting to shear as confining pressure increases.Thermal damage reduces the rock’s energy storage capacity and increases energy dissipation during loading.The brittleness index decreases with temperature and confining pressure,though granite still exhibits pronounced brittle behavior within the studied range.Distinct differences were observed in the AE temporal characteristics and energy evolution of granite samples under uniaxial and triaxial compression conditions.As the specimen approaches failure,the abrupt increase in AE hit rate occurs earlier than the corresponding rise in AE energy.The global b-value of the granite samples increased with treatment temperature,and the global b-value in triaxial compression tests was higher than that in uniaxial compression tests.The evolution of timedependent b-value also varied with increasing confining pressure.These findings,particularly the AE temporal characteristics and distinct b-value evolution under confinement of thermally damaged granite,provide important implications for microseismic-based stability assessment and early warning in thermally damaged rock masses.
基金Project(2021YFC2900200)supported by the National Key Research and Development Project of ChinaProject(20230203114SF)supported by the Key Research and Development Project of Jilin Province,China。
文摘Basalt fibers/7075 aluminum matrix composites were studied to meet the demand of aluminum alloy drill pipes for material wear resistance.The composites with different basalt fiber additions were prepared by hot pressed sintering and hot extrusion.The mechanical properties as well as friction and wear properties of the composites were studied by microstructure analysis,tensile experiments,friction and wear experiments.The results showed that basalt fibers were oriented and uniformly distributed and led to local grain refinement in the alloy matrix.The hardness and elongation of the composites were improved.The friction coefficient of the composites increased and then decreased,and the maximum wear depth and wear amount decreased,then increased,then decreased again with the growth of basalt fiber addition.Meanwhile,the inclusion of basalt fibers mitigated the uneven wear of the extruded 7075 aluminum alloy.The value of wear depth difference of 7075-0.2BF was the smallest,and that of 7075-2.0BF was close to it.The maximum wear depth and wear volume the 7075-0.2BF and 7075-2.0BF were also the smallest.The inhibition of uneven wear by basalt fibers enhanced of wear resistance for 7075 aluminum alloy,which has reference significance for improving the performance of aluminum alloy drill pipes.
