The corrosion behavior and microstructure characteristics of metal inert gas(MIG)welded dissimilar joints of the 6005A alloy modified with Sc(designated as 6005A+Sc)and the 5083 alloy were investigated using corrosion...The corrosion behavior and microstructure characteristics of metal inert gas(MIG)welded dissimilar joints of the 6005A alloy modified with Sc(designated as 6005A+Sc)and the 5083 alloy were investigated using corrosion tests and microscopy techniques.Results show that the dissimilar joints exhibit strong stress corrosion cracking(SCC)resistance,maintaining substantial strength during slow strain rate tensile tests.Notably,the heat-affected zone(HAZ)and base metal(BM)on the 6005A+Sc side show superior performance in terms of inter-granular corrosion(IGC)and exfoliation corrosion(EXCO)compared to the corresponding zones on the 5083 side.The lower corrosion resistance of the 5083-BM and the 5083-HAZ can be attributed to the presence of numerous Al_(2)Mg_(3)phases and micro-scaled Al_(6)(Mn,Fe)intermetallics,mainly distributed along the rolling direction.Conversely,the enhanced corrosion resistance of the 6005A+Sc-BM and the 6005A+Sc-HAZ can be attributed to the discontinuously distributed grain boundary precipitates(β-Mg_(2)Si),the smaller grain size,and the reduced corrosive current density.展开更多
Al−3.51Mg−0.42Mn−0.76Sc−0.40Zr(wt.%)alloy was prepared by selective laser melting(SLM)method.The mechanical properties and microstructure of the alloy after annealing at 300℃or 325℃for 6 h were studied.The tensile s...Al−3.51Mg−0.42Mn−0.76Sc−0.40Zr(wt.%)alloy was prepared by selective laser melting(SLM)method.The mechanical properties and microstructure of the alloy after annealing at 300℃or 325℃for 6 h were studied.The tensile strength,yield strength and elongation of the SLM alloy were 339 MPa,213 MPa and 24%,respectively.After annealing at 300℃for 6 h,the tensile and yield strength of the alloy were increased to 518 MPa and 505 MPa,respectively,and the elongation decreased to 13%.After annealing at 325℃for 6 h,the yield strength of the alloy was reduced to 483 MPa.The grain size of the alloy after annealing at 300℃and 325℃did not grow significantly,but the segregation of Mg element was significantly reduced.Nanoscale Al3(Sc,Zr)phase was precipitated from the alloy matrix,and its average size increased with the increase of annealing temperature.Therefore,the strength improvement of the annealed SLM aluminum alloy was mainly attributed to the precipitation strengthening of Al3(Sc,Zr),and the strengthening mechanism was mainly dislocation cutting mechanism.When the annealing temperature was too high,the coarsening of Al3(Sc,Zr)particles caused the strength to decrease.展开更多
The intergranular corrosion behavior of 2050 Al-Li alloy subjected to non-isothermal aging(NIA)treatment with varying pre-deformation amounts was investigated.Results indicate that the resistance to intergranular corr...The intergranular corrosion behavior of 2050 Al-Li alloy subjected to non-isothermal aging(NIA)treatment with varying pre-deformation amounts was investigated.Results indicate that the resistance to intergranular corrosion improves with increasing pre-deformation amouts.However,when the pre-deformation amount reaches 20%,the corrosion resistance deteriorates.Microstructural analyses via transmission electron microscopy(TEM)and electron backscatter diffraction(EBSD)reveal that as pre-deformation amount increases,the fraction of high-angle grain boundaries(HAGBs)decreases,while the proportion of low-angle grain boundaries(LAGBs)increases.This change provides additional nucleation sites for precipitates,leading to a reduction in T1 phase size and an increase in T1 phase density.The finer T1 phases contribute to a lower localized potential difference within the grains,slowering corrosion propagation.Furthermore,during corrosion,preferential dissolution of Li results in Cu enrichment along grain boundaries,which further reduces the intergranular corrosion resistance.展开更多
The effects of minor Sc and Zr additions on the mechanical properties and microstructure evolution of Al Zn Mg Cu alloys were studied using tensile tests, scanning electron microscopy (SEM) and transmission electron m...The effects of minor Sc and Zr additions on the mechanical properties and microstructure evolution of Al Zn Mg Cu alloys were studied using tensile tests, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The ultimate tensile strength of the peak-aged Al Zn Mg Cu alloy is improved by about 105 MPa with the addition of 0.10% Zr. An increase of about 133 MPa is observed with the joint addition of 0.07% Sc and 0.07% Zr. For the alloys modified with the minor addition of Sc and Zr (0.14%), the main strengthening mechanisms of minor addition of Sc and Zr are fine-grain strengthening, sub-structure strengthening and the Orowan strengthening mechanism produced by the Al3(Sc,Zr) and Al3Zr dispersoids. The volume of Al3Zr particles is less than that of Al3(Sc,Zr) particles, but the distribution of Al3(Sc,Zr) particles is more dispersed throughout the matrix leading to pinning the dislocations motion and restraining the recrystallization more effectively.展开更多
An ultrafine-grained Al−Zn−Mg−Zr alloy with superior mechanical performance was obtained by high passes of equal angular pressing(ECAP)and subsequent aging.After 8 ECAP passes and aging,the yield strength(YS)and ultim...An ultrafine-grained Al−Zn−Mg−Zr alloy with superior mechanical performance was obtained by high passes of equal angular pressing(ECAP)and subsequent aging.After 8 ECAP passes and aging,the yield strength(YS)and ultimate tensile strength(UTS)of the solid-solutioned alloy are significantly improved from(98±10)and(226±7)MPa to(405±9)and(427±9)MPa,respectively.A large elongation is also maintained((17.4±2.5)%).The microstructure features including grain refinement,morphology of precipitates,and dislocation density,were revealed with multiscale characterizations,including transmission electron microscopy,electron backscattered diffraction,and X-ray diffraction.After 8 passes of ECAP,the original coarse elongated grains are refined to a unique bimodal grain structure consisting of ultrafine equiaxed and lath-like grains.Additionally,the effects of ECAP and subsequent aging on the strengthening contribution of a variety of strengthening mechanisms,such as dislocation strengthening and precipitation strengthening,were discussed in detail.展开更多
Arc erosion behavior of Ag/Ni materials with different operation numbers was investigated by OM,3DOP and SEM.The results indicated that the arc erosion of Ag/10Ni electrical contact material fabricated by sintering−ex...Arc erosion behavior of Ag/Ni materials with different operation numbers was investigated by OM,3DOP and SEM.The results indicated that the arc erosion of Ag/10Ni electrical contact material fabricated by sintering−extrusion technology was more and more serious with the operation numbers increasing from 1000 to 40000.With the same operation numbers,the arc erosion on anode was more serious than that on cathode.Besides,the pores preferred to emerge around the arc effect spot during the first 10000 operations.And the morphology of the molten silver on cathode and anode was different due to the action of gravity and arc erosion.Furthermore,the relationships among arc energy,arc time,welding force,electric resistivity,temperature and mass change on contacts were discussed,which indicated that the mass loss on cathode was mainly caused by the fracture of molten bridge.展开更多
The evolution of microstructure and properties of Al−5.87Zn−2.07Mg−2.42Cu alloys during non-isothermal aging was studied.The mechanical properties of the alloy were tested by stretching at room temperature.The results...The evolution of microstructure and properties of Al−5.87Zn−2.07Mg−2.42Cu alloys during non-isothermal aging was studied.The mechanical properties of the alloy were tested by stretching at room temperature.The results show that in the non-isothermal aging process,when the alloy is cooled to 140℃,the ultimate tensile strength of the alloy reaches a maximum value of 582 MPa and the elongation is 11.9%.The microstructure was tested through a transmission electron microscope,and the experimental results show that the GP zones andη'phases are the main strengthening precipitates.At the cooling stage,when the temperature dropped to 180℃,the GP zones were precipitated again.Besides,the experimental results show that the main strengthening phase during non-isothermal aging isη'phases.展开更多
The porous NiTi(pNiTi)samples were produced by sintering evaporation using Ti−50.8Ni(at.%)gasatomized powders.The samples were analyzed by metallographic microscope and X-ray dispersive spectroscopy(XRD).A comparison ...The porous NiTi(pNiTi)samples were produced by sintering evaporation using Ti−50.8Ni(at.%)gasatomized powders.The samples were analyzed by metallographic microscope and X-ray dispersive spectroscopy(XRD).A comparison of nickel(Ni)release and cytocompatibility between pNiTi and dense NiTi(dNiTi)was made.The results showed that the pNiTi has good mechanical properties.Ni releases from pNiTi in vitro and in vivo are more serious than those form dNiTi.The proliferation and differentiation of cells cultured with the pNiTi extracting liquid are significantly worse,and the rate of early apoptosis is higher.In conclusion,pNiTi is mechanically similar to bone,but pNiTi releases more Ni and interferes with cell proliferation and differentiation.A significantly cautious approach should be adopted when using it as a medical implant.展开更多
The high temperature mechanical properties(250 ℃) and microstructure of a die-forged Al-5.87 Zn-2.07 Mg-2.42 Cu alloy after T6 heat treatment were investigated. High temperature tensile tests show that as the tempera...The high temperature mechanical properties(250 ℃) and microstructure of a die-forged Al-5.87 Zn-2.07 Mg-2.42 Cu alloy after T6 heat treatment were investigated. High temperature tensile tests show that as the temperature increases from room temperature to 250 ℃, the ultimate tensile strength of the alloy decreases from 638 to 304 MPa, and the elongation rises from 13.6% to 20.4%. Transmission electron microscopy(TEM) and electron backscattered diffraction(EBSD) were applied for microstructure characterization, which indicates that the increase of tensile temperature can lead to the coarsening of precipitates, drop of dislocation density, and increase of dynamic recovery. After tensile testing at 250 ℃, a sub-grain structure composed of a high fraction of small-angle grain boundary is formed.展开更多
Nonadiabatic holonomic quantum computers serve as the physical platform for nonadiabatic holonomic quantum computation.As quantum computation has entered the noisy intermediate-scale era,building accurate intermediate...Nonadiabatic holonomic quantum computers serve as the physical platform for nonadiabatic holonomic quantum computation.As quantum computation has entered the noisy intermediate-scale era,building accurate intermediate-scale nonadiabatic holo-nomic quantum computers is clearly necessary.Given that measurements are the sole means of extracting information,they play an indispensable role in nonadiabatic holonomic quantum computers.Accordingly,developing methods to reduce measurement errors in nonadiabatic holonomic quantum computers is of great importance.However,while much attention has been given to the research on nonadiabatic holonomic gates,the research on reducing measurement errors in nonadiabatic holonomic quantum computers is severely lacking.In this study,we propose a measurement error reduction method tailored for intermediate-scale nonadiabatic holonomic quantum computers.The reason we say this is because our method can not only reduce the measurement errors in the computer but also be useful in mitigating errors originating from nonadiabatic holonomic gates.Given these features,our method significantly advances the construction of accurate intermediate-scale nonadiabatic holonomic quantum computers.展开更多
基金financially supported by the Science and Technology Innovation Program of Hunan Province,China(No.2023RC3055)the Natural Science Foundation of Hunan Province,China(Nos.2023JJ30671,2020JJ4114)+5 种基金the Natural Science Foundation of Changsha City,China(No.Kq2208264)National Key Project of Research and Development Plan of China(Nos.2021YFC1910505,2021YFC1910504)the Young Core Teacher Foundation of Hunan Province,China(No.150220001)Key Research and Development Program of Guangdong Province,China(No.2020B010186002)the National Natural Science Foundation of China(No.51601229)the Key-Area Research and Development Program of Foshan City,China(No.2230032004640).
文摘The corrosion behavior and microstructure characteristics of metal inert gas(MIG)welded dissimilar joints of the 6005A alloy modified with Sc(designated as 6005A+Sc)and the 5083 alloy were investigated using corrosion tests and microscopy techniques.Results show that the dissimilar joints exhibit strong stress corrosion cracking(SCC)resistance,maintaining substantial strength during slow strain rate tensile tests.Notably,the heat-affected zone(HAZ)and base metal(BM)on the 6005A+Sc side show superior performance in terms of inter-granular corrosion(IGC)and exfoliation corrosion(EXCO)compared to the corresponding zones on the 5083 side.The lower corrosion resistance of the 5083-BM and the 5083-HAZ can be attributed to the presence of numerous Al_(2)Mg_(3)phases and micro-scaled Al_(6)(Mn,Fe)intermetallics,mainly distributed along the rolling direction.Conversely,the enhanced corrosion resistance of the 6005A+Sc-BM and the 6005A+Sc-HAZ can be attributed to the discontinuously distributed grain boundary precipitates(β-Mg_(2)Si),the smaller grain size,and the reduced corrosive current density.
基金the financial supports from the Natural Science Foundation of Hunan Province, China (Nos. 2020JJ4114, 2016JJ3151)the National Natural Science Foundation of China (No. 51601229)+2 种基金the Young Elite Scientist Sponsorship Program by CAST, China (No. 2015QNRC001)the Hunan Province Innovation Platform and Talent Plan Project, China (No. 2015RS4001)the Open-end Fund for the Valuable and Precision Instruments of Central South University, China (No. CSUZC201815)。
基金financially supported by the National Key Research and Development Program of China(No.2018YFB2001801)State’s Key Project of Research and Development Plan(No.2021YFC1910505)the Key Research and Development Program of Guangdong Province,China(No.2020B010186002)。
文摘Al−3.51Mg−0.42Mn−0.76Sc−0.40Zr(wt.%)alloy was prepared by selective laser melting(SLM)method.The mechanical properties and microstructure of the alloy after annealing at 300℃or 325℃for 6 h were studied.The tensile strength,yield strength and elongation of the SLM alloy were 339 MPa,213 MPa and 24%,respectively.After annealing at 300℃for 6 h,the tensile and yield strength of the alloy were increased to 518 MPa and 505 MPa,respectively,and the elongation decreased to 13%.After annealing at 325℃for 6 h,the yield strength of the alloy was reduced to 483 MPa.The grain size of the alloy after annealing at 300℃and 325℃did not grow significantly,but the segregation of Mg element was significantly reduced.Nanoscale Al3(Sc,Zr)phase was precipitated from the alloy matrix,and its average size increased with the increase of annealing temperature.Therefore,the strength improvement of the annealed SLM aluminum alloy was mainly attributed to the precipitation strengthening of Al3(Sc,Zr),and the strengthening mechanism was mainly dislocation cutting mechanism.When the annealing temperature was too high,the coarsening of Al3(Sc,Zr)particles caused the strength to decrease.
基金supported by the Postdoctoral Fellowship Program of CPSF,China(No.GZC20242033)the National Science and Technology Research Program of China(No.JPPT2023PXY01).
文摘The intergranular corrosion behavior of 2050 Al-Li alloy subjected to non-isothermal aging(NIA)treatment with varying pre-deformation amounts was investigated.Results indicate that the resistance to intergranular corrosion improves with increasing pre-deformation amouts.However,when the pre-deformation amount reaches 20%,the corrosion resistance deteriorates.Microstructural analyses via transmission electron microscopy(TEM)and electron backscatter diffraction(EBSD)reveal that as pre-deformation amount increases,the fraction of high-angle grain boundaries(HAGBs)decreases,while the proportion of low-angle grain boundaries(LAGBs)increases.This change provides additional nucleation sites for precipitates,leading to a reduction in T1 phase size and an increase in T1 phase density.The finer T1 phases contribute to a lower localized potential difference within the grains,slowering corrosion propagation.Furthermore,during corrosion,preferential dissolution of Li results in Cu enrichment along grain boundaries,which further reduces the intergranular corrosion resistance.
基金financially supported by the Natural Science Foundation of Hunan Province(Nos.2020JJ4114,2016JJ3151)the National Natural Science Foundation of China(No.51601229)+2 种基金the Young Elite Scientist Sponsorship Program by CAST(No.2015QNRC001)the Hunan Province Innovation Platform and Talent Plan Project,China(No.2015RS4001)the Open-End Fund for the Valuable and Precision Instruments of Central South University,China(No.CSUZC201815)。
文摘采用选择激光熔化(SLM)技术在不同工艺参数下制备Al-4.77Mn-1.37Mg-0.67Sc-0.25Zr合金(质量分数,%),通过拉伸试验和显微观察研究合金的组织和力学性能。结果表明:当能量密度为104~143 J/mm^(3)时,力学性能保持相对稳定;屈服强度为335~338 MPa,抗拉强度为397~400 MPa,伸长率均在11%以上。在此能量密度区间内,SLM合金缺陷和粗大金属间化合物较少,与此同时,有大量细小的Al Fe Mn Sc Zr相析出。当能量密度超过152 J/mm^(3)时,可以观察到一些孔洞和裂纹,且伸长率急剧下降。定量计算结果表明,该合金固溶强化、晶界强化和析出强化占比分别为44%、41%和15%。
基金financially supported by the Natural Science Foundation of Hunan Province,China(Nos.2020JJ4114,2016JJ3151)the National Natural Science Foundation of China(No.51601229)+2 种基金the Young Elite Scientist Sponsorship Program by CAST,China(No.2015QNRC001)the Hunan Province Innovation Platform and Talent Plan,China(No.2015RS4001)the Open-End Fund for the Valuable and Precision Instruments of Central South University,China(No.CSUZC201815)。
基金supported by the National Key Research and Development Program of China (No.2018YFB2001801)the National Key Project of Research and Development Plan (No.2021YFC1910505)+1 种基金the Hunan Provincial Natural Science Foundation of China (No.2020JJ5742)the Key Research and Development Program of Guangdong Province,China (No.2020B010186002).
基金Project (2016B090931004) supported by the Scientific and Research Plan of Guangdong Province, ChinaProject (51601229) supported by the National Natural Science Foundation of China。
文摘The effects of minor Sc and Zr additions on the mechanical properties and microstructure evolution of Al Zn Mg Cu alloys were studied using tensile tests, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The ultimate tensile strength of the peak-aged Al Zn Mg Cu alloy is improved by about 105 MPa with the addition of 0.10% Zr. An increase of about 133 MPa is observed with the joint addition of 0.07% Sc and 0.07% Zr. For the alloys modified with the minor addition of Sc and Zr (0.14%), the main strengthening mechanisms of minor addition of Sc and Zr are fine-grain strengthening, sub-structure strengthening and the Orowan strengthening mechanism produced by the Al3(Sc,Zr) and Al3Zr dispersoids. The volume of Al3Zr particles is less than that of Al3(Sc,Zr) particles, but the distribution of Al3(Sc,Zr) particles is more dispersed throughout the matrix leading to pinning the dislocations motion and restraining the recrystallization more effectively.
基金financially supported by the National Key Research and Development Plan,China(No.2021YFC1910500)。
文摘An ultrafine-grained Al−Zn−Mg−Zr alloy with superior mechanical performance was obtained by high passes of equal angular pressing(ECAP)and subsequent aging.After 8 ECAP passes and aging,the yield strength(YS)and ultimate tensile strength(UTS)of the solid-solutioned alloy are significantly improved from(98±10)and(226±7)MPa to(405±9)and(427±9)MPa,respectively.A large elongation is also maintained((17.4±2.5)%).The microstructure features including grain refinement,morphology of precipitates,and dislocation density,were revealed with multiscale characterizations,including transmission electron microscopy,electron backscattered diffraction,and X-ray diffraction.After 8 passes of ECAP,the original coarse elongated grains are refined to a unique bimodal grain structure consisting of ultrafine equiaxed and lath-like grains.Additionally,the effects of ECAP and subsequent aging on the strengthening contribution of a variety of strengthening mechanisms,such as dislocation strengthening and precipitation strengthening,were discussed in detail.
基金supported by the National Natural Science Foundation of China (No.51601225)Hunan Provincial Natural Science Foundation,China (No.2020JJ5742)。
文摘Arc erosion behavior of Ag/Ni materials with different operation numbers was investigated by OM,3DOP and SEM.The results indicated that the arc erosion of Ag/10Ni electrical contact material fabricated by sintering−extrusion technology was more and more serious with the operation numbers increasing from 1000 to 40000.With the same operation numbers,the arc erosion on anode was more serious than that on cathode.Besides,the pores preferred to emerge around the arc effect spot during the first 10000 operations.And the morphology of the molten silver on cathode and anode was different due to the action of gravity and arc erosion.Furthermore,the relationships among arc energy,arc time,welding force,electric resistivity,temperature and mass change on contacts were discussed,which indicated that the mass loss on cathode was mainly caused by the fracture of molten bridge.
基金the National Key Research and Development Program of China(No.2018YFB2001801)the Postdoctoral Science Foundation of Central South University,China(No.220363)the National Natural Science Foundation of China(No.51601229).
文摘The evolution of microstructure and properties of Al−5.87Zn−2.07Mg−2.42Cu alloys during non-isothermal aging was studied.The mechanical properties of the alloy were tested by stretching at room temperature.The results show that in the non-isothermal aging process,when the alloy is cooled to 140℃,the ultimate tensile strength of the alloy reaches a maximum value of 582 MPa and the elongation is 11.9%.The microstructure was tested through a transmission electron microscope,and the experimental results show that the GP zones andη'phases are the main strengthening precipitates.At the cooling stage,when the temperature dropped to 180℃,the GP zones were precipitated again.Besides,the experimental results show that the main strengthening phase during non-isothermal aging isη'phases.
文摘The porous NiTi(pNiTi)samples were produced by sintering evaporation using Ti−50.8Ni(at.%)gasatomized powders.The samples were analyzed by metallographic microscope and X-ray dispersive spectroscopy(XRD).A comparison of nickel(Ni)release and cytocompatibility between pNiTi and dense NiTi(dNiTi)was made.The results showed that the pNiTi has good mechanical properties.Ni releases from pNiTi in vitro and in vivo are more serious than those form dNiTi.The proliferation and differentiation of cells cultured with the pNiTi extracting liquid are significantly worse,and the rate of early apoptosis is higher.In conclusion,pNiTi is mechanically similar to bone,but pNiTi releases more Ni and interferes with cell proliferation and differentiation.A significantly cautious approach should be adopted when using it as a medical implant.
基金Project(220636)supported by the Postdoctoral Science Foundation of the Central South University,ChinaProject(2016B090931004)supported by the Guangdong Province Science and Research Plan,ChinaProject(51601229)supported by the National Natural Science Foundation of China。
文摘The high temperature mechanical properties(250 ℃) and microstructure of a die-forged Al-5.87 Zn-2.07 Mg-2.42 Cu alloy after T6 heat treatment were investigated. High temperature tensile tests show that as the temperature increases from room temperature to 250 ℃, the ultimate tensile strength of the alloy decreases from 638 to 304 MPa, and the elongation rises from 13.6% to 20.4%. Transmission electron microscopy(TEM) and electron backscattered diffraction(EBSD) were applied for microstructure characterization, which indicates that the increase of tensile temperature can lead to the coarsening of precipitates, drop of dislocation density, and increase of dynamic recovery. After tensile testing at 250 ℃, a sub-grain structure composed of a high fraction of small-angle grain boundary is formed.
基金supported by the National Natural Science Foundation of China(Grant No.12174224)。
文摘Nonadiabatic holonomic quantum computers serve as the physical platform for nonadiabatic holonomic quantum computation.As quantum computation has entered the noisy intermediate-scale era,building accurate intermediate-scale nonadiabatic holo-nomic quantum computers is clearly necessary.Given that measurements are the sole means of extracting information,they play an indispensable role in nonadiabatic holonomic quantum computers.Accordingly,developing methods to reduce measurement errors in nonadiabatic holonomic quantum computers is of great importance.However,while much attention has been given to the research on nonadiabatic holonomic gates,the research on reducing measurement errors in nonadiabatic holonomic quantum computers is severely lacking.In this study,we propose a measurement error reduction method tailored for intermediate-scale nonadiabatic holonomic quantum computers.The reason we say this is because our method can not only reduce the measurement errors in the computer but also be useful in mitigating errors originating from nonadiabatic holonomic gates.Given these features,our method significantly advances the construction of accurate intermediate-scale nonadiabatic holonomic quantum computers.
