Most of the so-called Bayan Obo fine-grained dolomite marbles collected from the main and east orebodies show a microporphyritic texture,namely the microphenocrysts are set in a very finegrained matrix,although nearly...Most of the so-called Bayan Obo fine-grained dolomite marbles collected from the main and east orebodies show a microporphyritic texture,namely the microphenocrysts are set in a very finegrained matrix,although nearly all of them have undergone recrystallization caused either by deformation or alteration.The texture seems likely to have maintained the original features.It is known that one of the most characteristic textures of volcanic rocks is the porphyritic texture,and the microporphyritic texture is a variety in which both the phenocrysts and the matrix are only distinguishable with the microscope.Therefore,the dolomite marbles in the main and east orebodies may be related to the extrusive carbonatites.In addition,there also occur some carbonatite sills and dykes with different textures at Bayan Obo.Thus,the Bayan Obo carbonatites are polyphase intrusive and extrusive carbonatites.展开更多
Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusi...Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusion speeds(3 and 6 mm/s).The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy,and the second phase showed streamline distribution along the extrusion direction(ED).With extrusion temperature increased from 260 to 320℃,the microstructure,texture,and mechanical properties of alloys changed slightly.The dynamic recrystallization(DRX)degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1,and the strength gradually decreased but elongation(EL)increased.With the extrusion speed increased from 3 to 6 mm/s,the grain sizes and DRX degree increased significantly,and the samples presented the typical<2111>-<1123>rare-earth(RE)textures.The alloy extruded at 260℃ with extrusion ratio of 10:1 and extrusion speed of 3 mm/s showed the tensile yield strength(TYS)of 213 MPa and EL of 30.6%.After quantitatively analyzing the contribution of strengthening mechanisms,it was found that the grain boundary strengthening and dislocation strengthening played major roles among strengthening contributions.These results provide some guidelines for enlarging the industrial application of extruded Mg-RE alloy.展开更多
The high-strength Mg-7Sn alloys(wt.%)with a heterogeneous grain structure were prepared by low-temperature extrusion(230°C)with the extrusion ratio of 9:1(9E230)and 17:1(17E230).The two extruded alloys contained ...The high-strength Mg-7Sn alloys(wt.%)with a heterogeneous grain structure were prepared by low-temperature extrusion(230°C)with the extrusion ratio of 9:1(9E230)and 17:1(17E230).The two extruded alloys contained fine dynamic recrystallization(DRX)grains(FG)and coarse un DRX grains(CG).The difference in deformability between CG and FG leads to the formation of heterogeneous grain structure.The average grain size and basal texture intensities increased while the volume fraction of CG decreased with increasing extrusion ratio.Tensile testing results indicated that the extruded 17E230 alloy exhibited higher tensile strengths than 9E230 alloy,whose tensile yield strength(σ_(0.2)),ultimate tensile strengths(σ_(b)),and elongation to failure(ε_(f))were 231.1 MPa,319.5MPa,and 12.54%respectively.The high tensile strengths of the extruded alloy mainly originated from grain refinement,texture strengthening,precipitation strengthening from a great number of nano-scale Mg_(2)Sn phases,solid solution strengthening and hetero-deformation induced(HDI)strengthening,while the good ductility of the alloy was also mainly attributed to grain refinement,activation of the non-basal slip systems and HDI hardening.展开更多
The microstructures and mechanical properties of Al-8.3Zn-3.3Cu-2.2Mg alloys prepared via hot extrusion and liquid forging methods were investigated.Results show that based on DEFORM simulation analysis,the optimal ho...The microstructures and mechanical properties of Al-8.3Zn-3.3Cu-2.2Mg alloys prepared via hot extrusion and liquid forging methods were investigated.Results show that based on DEFORM simulation analysis,the optimal hot extrusion parameters are determined as ingot initial temperature of 380°C and extrusion speed of 3 mm/s.The hot-extruded aluminum alloy after T6 heat treatment presents superior mechanical properties with yield strength of 519.6 MPa,ultimate tensile strength of 582.1 MPa,and elongation of 11.0%.Compared with the properties of gravity-cast and liquid-forged alloys,the yield strength of hot-extruded alloy increases by 30.8%and 4.9%,and the ultimate tensile strength improves by 43.5%and 10.2%,respectively.The significant improvement in tensile strength of the hot-extruded alloys is attributed to the elimination of casting defects and the refinement of matrix grain and eutectic phases.In addition,the hot-extruded alloy demonstrates superior plasticity compared with the liquid-forged alloy.This is because severe plastic deformation occurs during hot extrusion,which effectively breaks and disperses the eutectic phases,facilitating the dissolution and precipitation of the second phases and inhibiting the microcrack initiation.展开更多
The Mg-Y-Zn magnesium alloy system is known for the presence of Long-Period Stacking Ordered(LPSO)phases that improves strength and ductility with minimal amounts of alloying elements.Even better improvements are asso...The Mg-Y-Zn magnesium alloy system is known for the presence of Long-Period Stacking Ordered(LPSO)phases that improves strength and ductility with minimal amounts of alloying elements.Even better improvements are associated with the specific microstructure known as the Mille-Feuille(MF)structure that can occur in this alloy as well after proper heat treatment.This study systematically compares the traditional ingot metallurgy method with the Bridgman method(slow cooling),coupled with diverse heat treatments and extrusion process.Microscopic analyses reveal variations in the presence of LPSO phases,MF structure,and especially grain size,leading to divergent mechanical and corrosion properties.The Bridgman approach surprisingly stands out,ensuring superior mechanical properties due to kink and texture strengthening.展开更多
Traditional manufacturing processes for lightweight curved profiles are often associated with lengthy procedures,high costs,low efficiency,and high energy consumption.In order to solve this problem,a new staggered ext...Traditional manufacturing processes for lightweight curved profiles are often associated with lengthy procedures,high costs,low efficiency,and high energy consumption.In order to solve this problem,a new staggered extrusion(SE)process was used to form the curved profile of AZ31 magnesium alloy in this paper.The study investigates the mapping relationship between the curvature,microstructure,and mechanical properties of the formed profiles by using different eccentricities of the die.Scanning electron microscopy(SEM)and electron backscatter diffraction techniques are employed to examine the effects of different eccentricity values(e)on grain morphology,recrystallization mechanisms,texture,and Schmid factors of the products.The results demonstrate that the staggered extrusion method promotes the deep refinement of grain size in the extruded products,with an average grain size of only 15%of the original billet,reaching 12.28μm.The tensile strength and elongation of the curved profiles after extrusion under the eccentricity value of 10 mm,20 mm and 30 mm are significantly higher than those of the billet,with the tensile strength is increased to 250,270,235 MPa,and the engineering strain elongation increased to 10.5%,12.1%,15.9%.This indicates that staggered extrusion enables curvature control of the profiles while improving their strength.展开更多
This study compares the microstructural evolution,dynamic recrystallization(DRX)behavior,tensile properties,and age-hardenability between the newly developed high-speed-extrudable BA56 alloy and those of the widely re...This study compares the microstructural evolution,dynamic recrystallization(DRX)behavior,tensile properties,and age-hardenability between the newly developed high-speed-extrudable BA56 alloy and those of the widely recognized AZ31 alloy in industry.Unlike the AZ31 alloy,which retains partially unrecrystallized grains,the high-speed-extruded BA56 alloy demonstrates a coarser but entirely recrystallized and more homogeneous microstructure.The fine-grained structure and abundant Mg_(3)Bi_(2) particles in the BA56 extrusion billet significantly enhance its DRX behavior,thus enabling rapid and complete recrystallization during extrusion.The BA56 alloy contains band-like fragmented Mg_(3)Bi_(2) particles and numerous fine Mg_(3)Bi_(2) particles distributed throughout the material,in contrast to the sparse Al_(8)Mn_(5) particles in the AZ31 alloy.These features contribute to superior mechanical properties of the BA56 alloy,which achieves tensile yield and ultimate tensile strengths of 205 and 292 MPa,respectively,compared to 196 and 270 MPa for the AZ31 alloy.The superior strength of the BA56 alloy,even with its coarser grain size,can be explained by its elevated Hall-Petch constant and the strengthening contribution from the fine Mg_(3)Bi_(2) particles.Additionally,the BA56 alloy demonstrates significant age-hardenability,achieving a 22%enhancement in hardness following T5 aging,attributed to the precipitation of nanoscale Mg_(3)Bi_(2) and Mg_(17)Al_(12) phases.By contrast,the AZ31 alloy shows minimal hardening due to the absence of precipitate formation during aging.These findings suggest that the BA56 alloy is a promising candidate for the production of extruded Mg components requiring a combination of high productivity,superior mechanical performance,and wide-ranging process adaptability.展开更多
Fabricating Mg/Al laminate is an effective strategy to circumvent the inherently low formability and poor corrosion resistance of Mg alloys.Here,Mg/Al laminate with good bonding quality and mechanical properties was s...Fabricating Mg/Al laminate is an effective strategy to circumvent the inherently low formability and poor corrosion resistance of Mg alloys.Here,Mg/Al laminate with good bonding quality and mechanical properties was successfully fabricated via porthole die co-extrusion process using ZK60 Mg and TiB_(2)/6061Al composite as constituted layers.Integrating the results from microstructural characterization and mechanical testing,the effects of extrusion temperature on microstructure,interfacial structure,element diffusion,and mechanical properties were investigated.The results show that Mg/Al laminate achieves a sound welding quality by mechanical bonding and diffusion bonding.The obvious intermetallic compounds(βandγ)layer forms at Mg/Al interface,and its thickness increases to 8.3μm as the extrusion temperature reaches 400℃.High extrusion temperature promotes the dynamic recrystallization and grain growth of Mg and Al layers,while the dislocation density decreases.β/γinterface shows a coherent feature,whileγ/Mg interface is semi-coherent with a locally ordered transition zone of 4.5 nm.The rich Mg and Cr layers are found at TiB_(2)/6061 interface,which is conducive to improving the bonding quality.When the extrusion temperature is 370℃,the thickness of diffusion layer is around 5.0μm,and the bonding strength reaches 18.68 MPa,resulting in the best comprehensive mechanical properties.This work provides a new direction for the development of Mg/Al laminate with excellent strength and ductility.展开更多
Obtaining high strength in low-RE-alloyed Mg alloys(RE<6 wt%)remains a huge challenge so far.In this work,we fabricated a novel high-strength and low-RE-alloyed Mg-3Yb-0.6Zn-0.4Zr(wt%)alloy using the conventional e...Obtaining high strength in low-RE-alloyed Mg alloys(RE<6 wt%)remains a huge challenge so far.In this work,we fabricated a novel high-strength and low-RE-alloyed Mg-3Yb-0.6Zn-0.4Zr(wt%)alloy using the conventional extrusion at low temperature,which breaks through the stereotypical"fewer RE,lower strength"wisdom.The microstructure of the alloy and mechanical properties were examined with op-tical microscopy(OM),X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and Instron testing machine.This alloy exhibits a high tensile yield strength of 410 MPa and a favorable elongation of 7.8%,outperforming the majority of traditional high-strength Mg-Gd-Y(-Zn)-Zr extrusion alloys with high RE additions,at least 12 wt%.The high yield strength of the alloy is closely associated with the synergistic effect of submicron recrystallized grains and highly-textural hot-worked grains containing numerous dynamic precipitates and residual dislocations,rather than the widely-considered age-hardening in those heavy RE containing Mg alloys.This work provides an important reference for the development of high-performance extruded Mg alloys with low RE solutes.展开更多
Although the degradability and biosafety of magnesium alloys make them advantageous for biological applications,medical implants made of magnesium alloys often fail prematurely due to corrosion.Therefore,improving the...Although the degradability and biosafety of magnesium alloys make them advantageous for biological applications,medical implants made of magnesium alloys often fail prematurely due to corrosion.Therefore,improving the corrosion resistance of magnesium alloys has become an urgent problem in the alloy design process.In this study,we designed and prepared Mg-xZn-0.5Y-0.5Zr(x=1,2,and 3,wt%)alloys in a hot extruded state and analyzed their surface structure through scanning electron microscopy,energy dispersion spectrometry,and X-ray diffraction.It was found that increasing the Zn content refined the recrystallized grains in the alloy.Particularly in Mg-3Zn-0.5Y-0.5Zr,the I phase became finer,forming both granular and nanoscale needle-like particles.Surface characterization after the immersion experiment showed that the corrosion product layer was mainly composed of Mg(OH)_(2),Zn(OH)_(2),CaCO_(3),and hy-droxyapatite.The degradation rate of ZW305K was the lowest,measured as 4.1 and 6.0 mm·a^(-1) with the hydrogen precipitation method and weight loss method respectively.Electrochemical experiments further explained the corrosion circuit model of the alloy in solution and confirmed the earlier results.The maximum polarization resistance of ZW305K was 874.5Ω·cm^(2),and the lowest corrosion current density was 0.104 mA·cm^(-2).As a biomedical alloy,it must exhibit good biocompatibility,so the alloy was also tested through cytotoxicity,cell adhesion,and staining experiments.The cell viability of each group after 48 h was greater than 80%,showing that the addition of zinc enhances the alloy’s biocompatibility.In summary,the prepared alloys have the potential to be used as biodegradable implant materials.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 microstructure and mechanical properties of Mg−4.5Al−2.5Zn−0.3Mn−0.2Ca(wt.%,designated as AZ42)alloys in extruded(at extrusion ratios of 28,20 and 11.5)and peak-aged states were investigated,by using optical micro...The microstructure and mechanical properties of Mg−4.5Al−2.5Zn−0.3Mn−0.2Ca(wt.%,designated as AZ42)alloys in extruded(at extrusion ratios of 28,20 and 11.5)and peak-aged states were investigated,by using optical microscopy,scanning electron microscopy,energy dispersive spectrometry and electron backscatter diffraction.The results show that extrusion produces a typical basal fiber texture and streamlines of second phases.All samples exhibit the lowest Schmid factor of basal slip(SFb)and the superior tensile yield strength(TYS)along extrusion direction(ED).The sample with extrusion ratio of 20 exhibits the largest average grain size,but the smallest SFb which compensates for the disadvantage of grain coarsening and maintains the strength.After being peak-aged at 175℃for 48 h,the sample with the extrusion ratio of 20 shows the optimal TYS along all the directions,compared to the other samples.This hopes to provide useful information for optimizing the deformation parameters of the AZ42 alloys.展开更多
Investment casting shell moulds are widely applied to cast alloys, but how to efficiently form a hierarchical porous structure inside the wall is an innovation and challenge. In this research, porous shell moulds with...Investment casting shell moulds are widely applied to cast alloys, but how to efficiently form a hierarchical porous structure inside the wall is an innovation and challenge. In this research, porous shell moulds with three infill patterns(rectilinear, grid, and honeycomb) were prepared using bauxite slurry and slurry extrusionbased additive manufacturing technology, and the effects of infill patterns on the properties were evaluated. The hierarchical pores inside the wall are composed of the macropores formed by infills and the micropores among bauxite particles. Different infill patterns result in changes in distribution and shape of pores, thereby affecting the properties of the shell moulds. The honeycomb pattern has more comprehensive advantages compared to the other two infill patterns. The samples prepared with the honeycomb pattern exhibit the highest bending strength(11.62 MPa) and porosity(41.6%), as well as good heat-transfer ability, with an average shrinkage rate within 2.0%. This work provides an attractive feasibility for fabricating shell moulds with hierarchical porous walls.展开更多
This work managed the extrusion strain path by designing various extrusion die cavities,successfully realizing the texture modification for the ZK60 magnesium alloy.The mechanisms involving the texture dependence on t...This work managed the extrusion strain path by designing various extrusion die cavities,successfully realizing the texture modification for the ZK60 magnesium alloy.The mechanisms involving the texture dependence on the extrusion die cavity as well as their effects on the mechanical properties were emphatically investigated.Results showed that dynamic recrystallization refined the grain size and improved the microstructure homogeneity in the three extrusion specimens,but did not produce too large microstructure differences.By comparison,significant texture differences developed owing to the various extrusion die cavities,which here were mainly reflected in the strong or weak texture components for the c-axes//TD and the c-axes//ND.Such texture differences started from the deformation texture instead of the recrystallization texture whose roles only consisted in dispersing the texture component and reducing the texture intensity.The results from the finite element analysis and the visco-plastic self-consistent model indicated that,in order to accommodate the different strain components induced by the extrusion die cavities,slip systems or tension twinning were activated differently,and this was the critical reason causing the above texture differences.One modified Hall-Petch relationship was adopted to analyze the conjoint effects of grain refinement and texture variation on the yield stress.Additionally,the quantitative results about deformation mechanism activation fractions demonstrated that the texture variations influenced the competition relationships between the twinning induced deformation and the slip dominant deformation,and the former generally produced the lower yield stress and the increasing stage of strain hardening rate,while the latter produced the higher yield stress and the continuous decline of strain hardening rate.展开更多
The development of low-cost,high-performance Mg alloys is crucial to the industrial applications of large-scale production of Mg alloys.In this work,extruded Mg-5Bi-3Al alloy with excellent mechanical properties is su...The development of low-cost,high-performance Mg alloys is crucial to the industrial applications of large-scale production of Mg alloys.In this work,extruded Mg-5Bi-3Al alloy with excellent mechanical properties is successfully prepared by modifying the extrusion temperatures(240℃and 300℃).The extruded alloy obtained ultra-high strength(yield strength=380 MPa,ultimate tensile strength=418 MPa)and excellent plasticity(elongation=10.2%)at the extrusion temperature of 240℃,the main contributing factors are primarily attributed to the synergistic effect of ultrafine recrystallized grain size(~0.5µm)and high density of Mg_(3)Bi_(2)precipitates.Stacking faults within the sub-micron Mg_(3)Bi_(2)phase are observed in the E240 alloy,confirming the plastic deformation capability of Mg_(3)Bi_(2)phase.The effects of extrusion temperature on the microstructure,mechanical properties,and work-hardening behavior of the extruded Mg-5Bi-3Al alloys at room temperature are systematically investigated.The results suggest that decreasing the extrusion temperature can refine recrystallized grain size and Mg_(3)Bi_(2)phase size,and the quantity of Mg_(3)Bi_(2)phase is increased,while increasing the extrusion temperature can improve the degree of recrystallization and weaken texture.The work hardening rate is increased with the increased extrusion temperature,mainly due to the coarsening of grains and precipitates,and the weakening of texture.This work provides an experimental basis for preparing high-performance wrought Mg-5Bi-3Al alloys.展开更多
The slow phase transition from formⅡto formⅠhas always been an important factor that restricts the processing and application of polybutene-1(PB-1).After extensive efforts,a set of effective methods for promoting th...The slow phase transition from formⅡto formⅠhas always been an important factor that restricts the processing and application of polybutene-1(PB-1).After extensive efforts,a set of effective methods for promoting the phase transition rate in PB-1 was established by adjusting the crystallization,nucleation,and growth temperatures.Nevertheless,low-molecular-weight PB-1(LMWPB-1)faces challenges because this method requires a low crystallization temperature,which is difficult to achieve during extrusion processing.In this study,we attempted to increase the phase transition rate in PB-1 by changing the annealing temperature after processing rather than the crystallization temperature in the classical scheme.The results indicated that regardless of low-or high-molecular-weight PB-1,repeated annealing between 0 and 90℃could also promote formⅡto formⅠphase transition.The initial content of formⅠincreased with the heating and cooling cycles.The half-time of the phase transition(t_(1/2))was also shortened after heating/cooling.After 100 heating/cooling cycles,t_(1/2) was reduced to one-quarter of that without annealing,which had almost the same effect as the crystallization temperature at 25℃in promoting the phase transition.This study indicates that annealing after processing is also an important factor affecting the phase transition of PB-1,and should receive sufficient attention.展开更多
Pesticides play a pivotal role in modern agriculture. However, the pesticide industry faces significant challenges closely linked to major global concerns such as pesticide resistance, environmental pollution, food sa...Pesticides play a pivotal role in modern agriculture. However, the pesticide industry faces significant challenges closely linked to major global concerns such as pesticide resistance, environmental pollution, food safety, and crop yields. Developing safe, efficient, and environmentally friendly pesticides has become a key challenge for the industry. Recently, Qing Yang and colleagues unveiled the mode of action of a dual-functional protein, the ABCH transporter, which plays essential roles in lipid transport to construct the lipid barrier of insect cuticles and in pesticide detoxification within insects. Since ABCH transporters are critical for all insects but absent in mammals and plants, this elegant and exciting work provides a highly promising target for developing safe, low-resistance pesticides. Here, we highlight the groundbreaking discoveries made by Qing Yang's team in unraveling the intricate mechanisms of the ABCH transporter.展开更多
The effects of forward extrusion as well as extrusion combined with reversible torsion(KoBo extrusion),followed by additional deformation via the MaxStrain module of the Gleeble thermomechanical simulator,on the micro...The effects of forward extrusion as well as extrusion combined with reversible torsion(KoBo extrusion),followed by additional deformation via the MaxStrain module of the Gleeble thermomechanical simulator,on the microstructure,mechanical properties,and electrical conductivity of a Cu−0.7Mg(wt.%)alloy,were investigated.The simulation results highlighted the critical influence of processing history on determining the equivalent strain distribution.The sample subjected to forward extrusion at 400℃and subsequent MaxStrain processing(FM sample),possessed 76%lower grain size compared to the sample processed solely with MaxStrain(AM sample).Likewise,the KoBo-extruded and MaxStrain-processed sample(KM sample)exhibited 66%smaller grain size compared to the AM sample.Tensile test results revealed that the AM,FM,and KM samples,respectively,possessed 251%,288%,and 360%higher yield strength,and 95%,121%,and 169%higher tensile strength compared to the initial annealed alloy,as a result of grain refinement as well as deformation strengthening.Finally,the electrical conductivity measurements revealed that AM,FM,and KM samples,respectively,possessed electrical conductivity values of 37.9,35.6,and 32.0 MS/m,which,by considering their mechanical properties,makes them eligible to be categorized as high-strength and high-conductivity copper alloys.展开更多
Mg-1.2Y-1.2Ni(at.%)alloy was extruded at 400℃with an extrusion ratio of 16:1 and different rates from 1 to 6 mm/s.The effect of extrusion rate on microstructure and mechanical properties of the Mg-1.2Y-1.2Ni alloy wa...Mg-1.2Y-1.2Ni(at.%)alloy was extruded at 400℃with an extrusion ratio of 16:1 and different rates from 1 to 6 mm/s.The effect of extrusion rate on microstructure and mechanical properties of the Mg-1.2Y-1.2Ni alloy was systematically investigated.With the increase of extrusion rate,the average recrystallized grain size of Mg-1.2Y-1.2Ni alloy and mean particle diameter of Mg2Ni phase were increased,while the density of geometrically necessary dislocation and the intensity of the basal texture were decreased.When extrusion rate increases from 1 to 6 mm/s,the tensile yield strength(TYS)of asextruded Mg-1.2Y-1.2Ni alloy decreases from 501 to 281 MPa,while the elongation to failure increases from 1.5%to 6.2%.The Mg-1.2Y-1.2Ni alloy extruded at 3 mm/s obtained TYS of 421 MPa,the ultimate tensile strength(UTS)of 440 MPa and elongation to failure of 2.6%,respectively,exhibiting comprehensive mechanical properties with relatively good plasticity and ultrahigh strength.The ultrahigh TYS of 501 and 421 MPa was mainly due to the strengthening from ultrafine recrystallized grains,high volume fraction long period stacking ordered(LPSO)phases and high density dislocations.展开更多
基金supported by the National Natural Sciences Foundation of China(No. 40472057)the National Major Basic Development Project(2006CB403503)
文摘Most of the so-called Bayan Obo fine-grained dolomite marbles collected from the main and east orebodies show a microporphyritic texture,namely the microphenocrysts are set in a very finegrained matrix,although nearly all of them have undergone recrystallization caused either by deformation or alteration.The texture seems likely to have maintained the original features.It is known that one of the most characteristic textures of volcanic rocks is the porphyritic texture,and the microporphyritic texture is a variety in which both the phenocrysts and the matrix are only distinguishable with the microscope.Therefore,the dolomite marbles in the main and east orebodies may be related to the extrusive carbonatites.In addition,there also occur some carbonatite sills and dykes with different textures at Bayan Obo.Thus,the Bayan Obo carbonatites are polyphase intrusive and extrusive carbonatites.
基金supported by the National Science and Technology Major Project,China(No.2019-VI-0004-0118)the National Natural Science Foundation of China(No.51771152)the National Key R&D Program of China(No.2018YFB1106800)。
文摘Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusion speeds(3 and 6 mm/s).The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy,and the second phase showed streamline distribution along the extrusion direction(ED).With extrusion temperature increased from 260 to 320℃,the microstructure,texture,and mechanical properties of alloys changed slightly.The dynamic recrystallization(DRX)degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1,and the strength gradually decreased but elongation(EL)increased.With the extrusion speed increased from 3 to 6 mm/s,the grain sizes and DRX degree increased significantly,and the samples presented the typical<2111>-<1123>rare-earth(RE)textures.The alloy extruded at 260℃ with extrusion ratio of 10:1 and extrusion speed of 3 mm/s showed the tensile yield strength(TYS)of 213 MPa and EL of 30.6%.After quantitatively analyzing the contribution of strengthening mechanisms,it was found that the grain boundary strengthening and dislocation strengthening played major roles among strengthening contributions.These results provide some guidelines for enlarging the industrial application of extruded Mg-RE alloy.
基金supported by the Major Science and Technology Project of Gansu Province(Grant No.22ZD6GA008)the National Natural Science Foundation of China(Nos.52261027,52001152 and 51961021)+2 种基金the Open Project of State Key Laboratory for Mechanical Behavior of Materials(20192102)Undergraduate Innovation and Entrepreneurship Training Program(Nos.DC20231482,DC20231188 and DC20231558)Gansu Provincial Excellent Graduate Students“Innovation Star”Program(2022CXZX-394)。
文摘The high-strength Mg-7Sn alloys(wt.%)with a heterogeneous grain structure were prepared by low-temperature extrusion(230°C)with the extrusion ratio of 9:1(9E230)and 17:1(17E230).The two extruded alloys contained fine dynamic recrystallization(DRX)grains(FG)and coarse un DRX grains(CG).The difference in deformability between CG and FG leads to the formation of heterogeneous grain structure.The average grain size and basal texture intensities increased while the volume fraction of CG decreased with increasing extrusion ratio.Tensile testing results indicated that the extruded 17E230 alloy exhibited higher tensile strengths than 9E230 alloy,whose tensile yield strength(σ_(0.2)),ultimate tensile strengths(σ_(b)),and elongation to failure(ε_(f))were 231.1 MPa,319.5MPa,and 12.54%respectively.The high tensile strengths of the extruded alloy mainly originated from grain refinement,texture strengthening,precipitation strengthening from a great number of nano-scale Mg_(2)Sn phases,solid solution strengthening and hetero-deformation induced(HDI)strengthening,while the good ductility of the alloy was also mainly attributed to grain refinement,activation of the non-basal slip systems and HDI hardening.
基金Natural Science Foundation of Shandong Province of China(ZR2023QE193)。
文摘The microstructures and mechanical properties of Al-8.3Zn-3.3Cu-2.2Mg alloys prepared via hot extrusion and liquid forging methods were investigated.Results show that based on DEFORM simulation analysis,the optimal hot extrusion parameters are determined as ingot initial temperature of 380°C and extrusion speed of 3 mm/s.The hot-extruded aluminum alloy after T6 heat treatment presents superior mechanical properties with yield strength of 519.6 MPa,ultimate tensile strength of 582.1 MPa,and elongation of 11.0%.Compared with the properties of gravity-cast and liquid-forged alloys,the yield strength of hot-extruded alloy increases by 30.8%and 4.9%,and the ultimate tensile strength improves by 43.5%and 10.2%,respectively.The significant improvement in tensile strength of the hot-extruded alloys is attributed to the elimination of casting defects and the refinement of matrix grain and eutectic phases.In addition,the hot-extruded alloy demonstrates superior plasticity compared with the liquid-forged alloy.This is because severe plastic deformation occurs during hot extrusion,which effectively breaks and disperses the eutectic phases,facilitating the dissolution and precipitation of the second phases and inhibiting the microcrack initiation.
基金supported by Japan Society for the Promotion of Science(KAKENHI Grant-in-Aid for Scientific Research,18H05475,18H05476 and JP20H00312)MRC International Collaborative Research Grant+4 种基金The authors would like to thank the Czech Science Foundation(Project No.22-22248S)specific university research(A1_FCHT_2024_007)for financial supportsupported by the Ministry of Education,Youth,and Sports of the Czech Republic.Project No.CZ.02.01.01/00/22_008/0004591co-funded by the European UnionCzechNanoLab project LM2023051 funded by MEYS CR is gratefully acknowledged for the financial support of the measurements/sample fabrication at LNSM Research Infrastructure。
文摘The Mg-Y-Zn magnesium alloy system is known for the presence of Long-Period Stacking Ordered(LPSO)phases that improves strength and ductility with minimal amounts of alloying elements.Even better improvements are associated with the specific microstructure known as the Mille-Feuille(MF)structure that can occur in this alloy as well after proper heat treatment.This study systematically compares the traditional ingot metallurgy method with the Bridgman method(slow cooling),coupled with diverse heat treatments and extrusion process.Microscopic analyses reveal variations in the presence of LPSO phases,MF structure,and especially grain size,leading to divergent mechanical and corrosion properties.The Bridgman approach surprisingly stands out,ensuring superior mechanical properties due to kink and texture strengthening.
基金Project(JQ2022E004)supported by the Natural Science Foundation of Heilongjiang Province,China。
文摘Traditional manufacturing processes for lightweight curved profiles are often associated with lengthy procedures,high costs,low efficiency,and high energy consumption.In order to solve this problem,a new staggered extrusion(SE)process was used to form the curved profile of AZ31 magnesium alloy in this paper.The study investigates the mapping relationship between the curvature,microstructure,and mechanical properties of the formed profiles by using different eccentricities of the die.Scanning electron microscopy(SEM)and electron backscatter diffraction techniques are employed to examine the effects of different eccentricity values(e)on grain morphology,recrystallization mechanisms,texture,and Schmid factors of the products.The results demonstrate that the staggered extrusion method promotes the deep refinement of grain size in the extruded products,with an average grain size of only 15%of the original billet,reaching 12.28μm.The tensile strength and elongation of the curved profiles after extrusion under the eccentricity value of 10 mm,20 mm and 30 mm are significantly higher than those of the billet,with the tensile strength is increased to 250,270,235 MPa,and the engineering strain elongation increased to 10.5%,12.1%,15.9%.This indicates that staggered extrusion enables curvature control of the profiles while improving their strength.
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Korea government(MSIT)(Nos.RS-2024–00351052 and RS-2024–00450561).
文摘This study compares the microstructural evolution,dynamic recrystallization(DRX)behavior,tensile properties,and age-hardenability between the newly developed high-speed-extrudable BA56 alloy and those of the widely recognized AZ31 alloy in industry.Unlike the AZ31 alloy,which retains partially unrecrystallized grains,the high-speed-extruded BA56 alloy demonstrates a coarser but entirely recrystallized and more homogeneous microstructure.The fine-grained structure and abundant Mg_(3)Bi_(2) particles in the BA56 extrusion billet significantly enhance its DRX behavior,thus enabling rapid and complete recrystallization during extrusion.The BA56 alloy contains band-like fragmented Mg_(3)Bi_(2) particles and numerous fine Mg_(3)Bi_(2) particles distributed throughout the material,in contrast to the sparse Al_(8)Mn_(5) particles in the AZ31 alloy.These features contribute to superior mechanical properties of the BA56 alloy,which achieves tensile yield and ultimate tensile strengths of 205 and 292 MPa,respectively,compared to 196 and 270 MPa for the AZ31 alloy.The superior strength of the BA56 alloy,even with its coarser grain size,can be explained by its elevated Hall-Petch constant and the strengthening contribution from the fine Mg_(3)Bi_(2) particles.Additionally,the BA56 alloy demonstrates significant age-hardenability,achieving a 22%enhancement in hardness following T5 aging,attributed to the precipitation of nanoscale Mg_(3)Bi_(2) and Mg_(17)Al_(12) phases.By contrast,the AZ31 alloy shows minimal hardening due to the absence of precipitate formation during aging.These findings suggest that the BA56 alloy is a promising candidate for the production of extruded Mg components requiring a combination of high productivity,superior mechanical performance,and wide-ranging process adaptability.
基金supports from the National Natural Science Foundation of China(52175338 and 52222510)Science Fund for Distinguished Young Scholars of Shandong Province(ZR2021JQ21)Key Research and Development Program of Shandong Province(2021ZLGX01).
文摘Fabricating Mg/Al laminate is an effective strategy to circumvent the inherently low formability and poor corrosion resistance of Mg alloys.Here,Mg/Al laminate with good bonding quality and mechanical properties was successfully fabricated via porthole die co-extrusion process using ZK60 Mg and TiB_(2)/6061Al composite as constituted layers.Integrating the results from microstructural characterization and mechanical testing,the effects of extrusion temperature on microstructure,interfacial structure,element diffusion,and mechanical properties were investigated.The results show that Mg/Al laminate achieves a sound welding quality by mechanical bonding and diffusion bonding.The obvious intermetallic compounds(βandγ)layer forms at Mg/Al interface,and its thickness increases to 8.3μm as the extrusion temperature reaches 400℃.High extrusion temperature promotes the dynamic recrystallization and grain growth of Mg and Al layers,while the dislocation density decreases.β/γinterface shows a coherent feature,whileγ/Mg interface is semi-coherent with a locally ordered transition zone of 4.5 nm.The rich Mg and Cr layers are found at TiB_(2)/6061 interface,which is conducive to improving the bonding quality.When the extrusion temperature is 370℃,the thickness of diffusion layer is around 5.0μm,and the bonding strength reaches 18.68 MPa,resulting in the best comprehensive mechanical properties.This work provides a new direction for the development of Mg/Al laminate with excellent strength and ductility.
基金supported by National Natural Science Foundation of China(52201111,52201137,52275389)Taiyuan University of Science and Technology Scientific Research Initial Funding(20232102)+1 种基金Reward funds for excellent doctor of work in coming to Shanxi(No.20242068)Special fund for Scienceand Technology Innovation Teamsof ShanxiProvince.
文摘Obtaining high strength in low-RE-alloyed Mg alloys(RE<6 wt%)remains a huge challenge so far.In this work,we fabricated a novel high-strength and low-RE-alloyed Mg-3Yb-0.6Zn-0.4Zr(wt%)alloy using the conventional extrusion at low temperature,which breaks through the stereotypical"fewer RE,lower strength"wisdom.The microstructure of the alloy and mechanical properties were examined with op-tical microscopy(OM),X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and Instron testing machine.This alloy exhibits a high tensile yield strength of 410 MPa and a favorable elongation of 7.8%,outperforming the majority of traditional high-strength Mg-Gd-Y(-Zn)-Zr extrusion alloys with high RE additions,at least 12 wt%.The high yield strength of the alloy is closely associated with the synergistic effect of submicron recrystallized grains and highly-textural hot-worked grains containing numerous dynamic precipitates and residual dislocations,rather than the widely-considered age-hardening in those heavy RE containing Mg alloys.This work provides an important reference for the development of high-performance extruded Mg alloys with low RE solutes.
基金supported by the National Natural Science Foundation of China(Nos.52371070 and 52271249),the Key Research and Development Program of Shaanxi,China(No.2023-YBGY-488)the State Key Laboratory of Solidification Processing in Northwestern Polytechnical University(No.SKLSP202415)Additional support was provided by the Xi’an Talent Plan,China(No.XAYC240016)。
文摘Although the degradability and biosafety of magnesium alloys make them advantageous for biological applications,medical implants made of magnesium alloys often fail prematurely due to corrosion.Therefore,improving the corrosion resistance of magnesium alloys has become an urgent problem in the alloy design process.In this study,we designed and prepared Mg-xZn-0.5Y-0.5Zr(x=1,2,and 3,wt%)alloys in a hot extruded state and analyzed their surface structure through scanning electron microscopy,energy dispersion spectrometry,and X-ray diffraction.It was found that increasing the Zn content refined the recrystallized grains in the alloy.Particularly in Mg-3Zn-0.5Y-0.5Zr,the I phase became finer,forming both granular and nanoscale needle-like particles.Surface characterization after the immersion experiment showed that the corrosion product layer was mainly composed of Mg(OH)_(2),Zn(OH)_(2),CaCO_(3),and hy-droxyapatite.The degradation rate of ZW305K was the lowest,measured as 4.1 and 6.0 mm·a^(-1) with the hydrogen precipitation method and weight loss method respectively.Electrochemical experiments further explained the corrosion circuit model of the alloy in solution and confirmed the earlier results.The maximum polarization resistance of ZW305K was 874.5Ω·cm^(2),and the lowest corrosion current density was 0.104 mA·cm^(-2).As a biomedical alloy,it must exhibit good biocompatibility,so the alloy was also tested through cytotoxicity,cell adhesion,and staining experiments.The cell viability of each group after 48 h was greater than 80%,showing that the addition of zinc enhances the alloy’s biocompatibility.In summary,the prepared alloys have the potential to be used as biodegradable implant materials.
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supported by the National Natural Science Foundation of China(No.51904036)the Hunan Provincial Key Research and Development Program,China(No.2023GK2049)+2 种基金Changsha Municipal Natural Science Foundation,China(Nos.kq2402016,kq2402014)the Postgraduate Scientific Research Innovation Project of Hunan Province,China(No.CX20240772)the Sichuan Science and Technology Program,China(No.2024NSFSC0151)。
文摘The microstructure and mechanical properties of Mg−4.5Al−2.5Zn−0.3Mn−0.2Ca(wt.%,designated as AZ42)alloys in extruded(at extrusion ratios of 28,20 and 11.5)and peak-aged states were investigated,by using optical microscopy,scanning electron microscopy,energy dispersive spectrometry and electron backscatter diffraction.The results show that extrusion produces a typical basal fiber texture and streamlines of second phases.All samples exhibit the lowest Schmid factor of basal slip(SFb)and the superior tensile yield strength(TYS)along extrusion direction(ED).The sample with extrusion ratio of 20 exhibits the largest average grain size,but the smallest SFb which compensates for the disadvantage of grain coarsening and maintains the strength.After being peak-aged at 175℃for 48 h,the sample with the extrusion ratio of 20 shows the optimal TYS along all the directions,compared to the other samples.This hopes to provide useful information for optimizing the deformation parameters of the AZ42 alloys.
基金financially supported by the National Natural Science Foundation of China (No. 52062029)the Key Science and Technology Project of Gansu Province (No. 18YF1GA064)the Natural Science Foundation of Gansu Provence (No. 25JRRA094)。
文摘Investment casting shell moulds are widely applied to cast alloys, but how to efficiently form a hierarchical porous structure inside the wall is an innovation and challenge. In this research, porous shell moulds with three infill patterns(rectilinear, grid, and honeycomb) were prepared using bauxite slurry and slurry extrusionbased additive manufacturing technology, and the effects of infill patterns on the properties were evaluated. The hierarchical pores inside the wall are composed of the macropores formed by infills and the micropores among bauxite particles. Different infill patterns result in changes in distribution and shape of pores, thereby affecting the properties of the shell moulds. The honeycomb pattern has more comprehensive advantages compared to the other two infill patterns. The samples prepared with the honeycomb pattern exhibit the highest bending strength(11.62 MPa) and porosity(41.6%), as well as good heat-transfer ability, with an average shrinkage rate within 2.0%. This work provides an attractive feasibility for fabricating shell moulds with hierarchical porous walls.
基金supported by National Natural Science Foundation of China(Grant No.52205344,51925401)Postdoctoral Research Foundation of China(Grant No.2023M732398)+1 种基金National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact(Grant No.WDZC2023-1)Key Research and Development Program of Shandong Province(Grant No.2023CXPT066).
文摘This work managed the extrusion strain path by designing various extrusion die cavities,successfully realizing the texture modification for the ZK60 magnesium alloy.The mechanisms involving the texture dependence on the extrusion die cavity as well as their effects on the mechanical properties were emphatically investigated.Results showed that dynamic recrystallization refined the grain size and improved the microstructure homogeneity in the three extrusion specimens,but did not produce too large microstructure differences.By comparison,significant texture differences developed owing to the various extrusion die cavities,which here were mainly reflected in the strong or weak texture components for the c-axes//TD and the c-axes//ND.Such texture differences started from the deformation texture instead of the recrystallization texture whose roles only consisted in dispersing the texture component and reducing the texture intensity.The results from the finite element analysis and the visco-plastic self-consistent model indicated that,in order to accommodate the different strain components induced by the extrusion die cavities,slip systems or tension twinning were activated differently,and this was the critical reason causing the above texture differences.One modified Hall-Petch relationship was adopted to analyze the conjoint effects of grain refinement and texture variation on the yield stress.Additionally,the quantitative results about deformation mechanism activation fractions demonstrated that the texture variations influenced the competition relationships between the twinning induced deformation and the slip dominant deformation,and the former generally produced the lower yield stress and the increasing stage of strain hardening rate,while the latter produced the higher yield stress and the continuous decline of strain hardening rate.
基金supported by the National Natural Science Foundation of China[grant nos.52371005,52022017,and 51927801]Fundamental Research Funds for the Central Universities.E.G.thanks Xiaomi Foundation for support.
文摘The development of low-cost,high-performance Mg alloys is crucial to the industrial applications of large-scale production of Mg alloys.In this work,extruded Mg-5Bi-3Al alloy with excellent mechanical properties is successfully prepared by modifying the extrusion temperatures(240℃and 300℃).The extruded alloy obtained ultra-high strength(yield strength=380 MPa,ultimate tensile strength=418 MPa)and excellent plasticity(elongation=10.2%)at the extrusion temperature of 240℃,the main contributing factors are primarily attributed to the synergistic effect of ultrafine recrystallized grain size(~0.5µm)and high density of Mg_(3)Bi_(2)precipitates.Stacking faults within the sub-micron Mg_(3)Bi_(2)phase are observed in the E240 alloy,confirming the plastic deformation capability of Mg_(3)Bi_(2)phase.The effects of extrusion temperature on the microstructure,mechanical properties,and work-hardening behavior of the extruded Mg-5Bi-3Al alloys at room temperature are systematically investigated.The results suggest that decreasing the extrusion temperature can refine recrystallized grain size and Mg_(3)Bi_(2)phase size,and the quantity of Mg_(3)Bi_(2)phase is increased,while increasing the extrusion temperature can improve the degree of recrystallization and weaken texture.The work hardening rate is increased with the increased extrusion temperature,mainly due to the coarsening of grains and precipitates,and the weakening of texture.This work provides an experimental basis for preparing high-performance wrought Mg-5Bi-3Al alloys.
基金financially supported by the National Natural Science Foundation of China(No.22175183)。
文摘The slow phase transition from formⅡto formⅠhas always been an important factor that restricts the processing and application of polybutene-1(PB-1).After extensive efforts,a set of effective methods for promoting the phase transition rate in PB-1 was established by adjusting the crystallization,nucleation,and growth temperatures.Nevertheless,low-molecular-weight PB-1(LMWPB-1)faces challenges because this method requires a low crystallization temperature,which is difficult to achieve during extrusion processing.In this study,we attempted to increase the phase transition rate in PB-1 by changing the annealing temperature after processing rather than the crystallization temperature in the classical scheme.The results indicated that regardless of low-or high-molecular-weight PB-1,repeated annealing between 0 and 90℃could also promote formⅡto formⅠphase transition.The initial content of formⅠincreased with the heating and cooling cycles.The half-time of the phase transition(t_(1/2))was also shortened after heating/cooling.After 100 heating/cooling cycles,t_(1/2) was reduced to one-quarter of that without annealing,which had almost the same effect as the crystallization temperature at 25℃in promoting the phase transition.This study indicates that annealing after processing is also an important factor affecting the phase transition of PB-1,and should receive sufficient attention.
基金National Natural Science Foundation of China(32471265).
文摘Pesticides play a pivotal role in modern agriculture. However, the pesticide industry faces significant challenges closely linked to major global concerns such as pesticide resistance, environmental pollution, food safety, and crop yields. Developing safe, efficient, and environmentally friendly pesticides has become a key challenge for the industry. Recently, Qing Yang and colleagues unveiled the mode of action of a dual-functional protein, the ABCH transporter, which plays essential roles in lipid transport to construct the lipid barrier of insect cuticles and in pesticide detoxification within insects. Since ABCH transporters are critical for all insects but absent in mammals and plants, this elegant and exciting work provides a highly promising target for developing safe, low-resistance pesticides. Here, we highlight the groundbreaking discoveries made by Qing Yang's team in unraveling the intricate mechanisms of the ABCH transporter.
基金financially supported by Silesian University of Technology,Poland(No.11/030/BK_23/1127)V?B–Technical University of Ostrava Czech Republic(No.CZ.02.1.01/0.0/0.0/17_049/0008399)。
文摘The effects of forward extrusion as well as extrusion combined with reversible torsion(KoBo extrusion),followed by additional deformation via the MaxStrain module of the Gleeble thermomechanical simulator,on the microstructure,mechanical properties,and electrical conductivity of a Cu−0.7Mg(wt.%)alloy,were investigated.The simulation results highlighted the critical influence of processing history on determining the equivalent strain distribution.The sample subjected to forward extrusion at 400℃and subsequent MaxStrain processing(FM sample),possessed 76%lower grain size compared to the sample processed solely with MaxStrain(AM sample).Likewise,the KoBo-extruded and MaxStrain-processed sample(KM sample)exhibited 66%smaller grain size compared to the AM sample.Tensile test results revealed that the AM,FM,and KM samples,respectively,possessed 251%,288%,and 360%higher yield strength,and 95%,121%,and 169%higher tensile strength compared to the initial annealed alloy,as a result of grain refinement as well as deformation strengthening.Finally,the electrical conductivity measurements revealed that AM,FM,and KM samples,respectively,possessed electrical conductivity values of 37.9,35.6,and 32.0 MS/m,which,by considering their mechanical properties,makes them eligible to be categorized as high-strength and high-conductivity copper alloys.
基金the financial support from the National Natural Science Foundation of China(No.12164004)the Jiangxi Provincial Natural Science Foundation(Nos.20242BAB25210,20232BCJ25067,20232BAB214004 and 20224BAB204029)+2 种基金the Foundation of Education Department of Jiangxi Provincial(Nos.GJJ2201247 and GJJ211436)the Young and Middle-aged Teachers Education Scientific Research Project of Fujian Province(No.JAT231008)supported by Sinoma Institute of Materials Research(Guang Zhou)Co.,Ltd(SIMR).
文摘Mg-1.2Y-1.2Ni(at.%)alloy was extruded at 400℃with an extrusion ratio of 16:1 and different rates from 1 to 6 mm/s.The effect of extrusion rate on microstructure and mechanical properties of the Mg-1.2Y-1.2Ni alloy was systematically investigated.With the increase of extrusion rate,the average recrystallized grain size of Mg-1.2Y-1.2Ni alloy and mean particle diameter of Mg2Ni phase were increased,while the density of geometrically necessary dislocation and the intensity of the basal texture were decreased.When extrusion rate increases from 1 to 6 mm/s,the tensile yield strength(TYS)of asextruded Mg-1.2Y-1.2Ni alloy decreases from 501 to 281 MPa,while the elongation to failure increases from 1.5%to 6.2%.The Mg-1.2Y-1.2Ni alloy extruded at 3 mm/s obtained TYS of 421 MPa,the ultimate tensile strength(UTS)of 440 MPa and elongation to failure of 2.6%,respectively,exhibiting comprehensive mechanical properties with relatively good plasticity and ultrahigh strength.The ultrahigh TYS of 501 and 421 MPa was mainly due to the strengthening from ultrafine recrystallized grains,high volume fraction long period stacking ordered(LPSO)phases and high density dislocations.
