Mechanical properties of aluminum−silicon−copper alloys are enhanced through precipitation hardening.The response of these alloys to age-hardening is very slow.To overcome this problem,0.2,0.4 and 0.7 wt.%magnesium we...Mechanical properties of aluminum−silicon−copper alloys are enhanced through precipitation hardening.The response of these alloys to age-hardening is very slow.To overcome this problem,0.2,0.4 and 0.7 wt.%magnesium were added to Al−10.5Si−3.4Cu alloy.The new alloys were subjected to two types of precipitation hardening processes different in the solutionizing stage.The results showed that the presence of various amounts of magnesium in the composition of this alloy accelerates the response to ageing treatments,increasing the hardness and strength.Higher mechanical properties can be achieved when the alloys were subjected to a two-stage solution heat treatment.It is found that Al−10.5Si−3.4Cu alloy containing 0.2 wt.%Mg treated through a two-stage solution process,has optimum properties with ultimate tensile strength of 383.9 MPa,yield strength of 289.7 MPa and elongation of 3.97%,and can be used as a substitute for a large number of aluminum castings which need high strength and excellent castability.展开更多
Zr was added to Ti−Nb−Fe alloys to develop low elastic modulus and high strengthβ-Ti alloys for biomedical applications.Ingots of Ti−12Nb−2Fe−(2,4,6,8,10)Zr(at.%)were prepared by arc melting and then subjected to hom...Zr was added to Ti−Nb−Fe alloys to develop low elastic modulus and high strengthβ-Ti alloys for biomedical applications.Ingots of Ti−12Nb−2Fe−(2,4,6,8,10)Zr(at.%)were prepared by arc melting and then subjected to homogenization,cold rolling,and solution treatments.The phases and microstructures of the alloys were analyzed by optical microscopy,X-ray diffraction,and transmission electron microscopy.The mechanical properties were measured by tensile tests.The results indicate that Zr and Fe cause a remarkable solid-solution strengthening effect on the alloys;thus,all the alloys show yield and ultimate tensile strengths higher than 510 MPa and 730 MPa,respectively.Zr plays a weak role in the deformation mechanism.Further,twinning occurs in all the deformed alloys and is beneficial to both strength and plasticity.Ti−12Nb−2Fe−(8,10)Zr alloys with metastableβphases show low elastic modulus,high tensile strength,and good plasticity and are suitable candidate materials for biomedical implants.展开更多
Ab initio calculations are used to understand the fundamental mechanism of the solid solution softening/hardening of the Mo-binary system.The results reveal that the Mo-Ti,Mo-Ta,Mo-Nb,and Mo-W interactions are primari...Ab initio calculations are used to understand the fundamental mechanism of the solid solution softening/hardening of the Mo-binary system.The results reveal that the Mo-Ti,Mo-Ta,Mo-Nb,and Mo-W interactions are primarily attractive with negative heats of formation,while the interactions of Mo-Re,and Mo-Zr would be mainly repulsive with positive heats of formation.It is also shown that the addition of Re and Zr would cause the solid solution softening of Mo by the decrease of the unstable stacking fault energy and the increase of ductility.On the contrary,the elements of W,Ta,Ti,and Nb could bring about the solid-solution hardening of Mo through the impediment of the slip of the dislocation and the decrease of ductility.Electronic structures indicate that the weaker/stronger chemical bonding due to the alloying elements should fundamentally induce the solid solution softening/hardening of Mo.The results are discussed and compared with available evidence in literatures,which could deepen the fundamental understanding of the solid solution softening/hardening of the binary metallic system.展开更多
文摘Mechanical properties of aluminum−silicon−copper alloys are enhanced through precipitation hardening.The response of these alloys to age-hardening is very slow.To overcome this problem,0.2,0.4 and 0.7 wt.%magnesium were added to Al−10.5Si−3.4Cu alloy.The new alloys were subjected to two types of precipitation hardening processes different in the solutionizing stage.The results showed that the presence of various amounts of magnesium in the composition of this alloy accelerates the response to ageing treatments,increasing the hardness and strength.Higher mechanical properties can be achieved when the alloys were subjected to a two-stage solution heat treatment.It is found that Al−10.5Si−3.4Cu alloy containing 0.2 wt.%Mg treated through a two-stage solution process,has optimum properties with ultimate tensile strength of 383.9 MPa,yield strength of 289.7 MPa and elongation of 3.97%,and can be used as a substitute for a large number of aluminum castings which need high strength and excellent castability.
基金the Natural Science Foundation of Shanghai,China(No.15ZR1428400)Shanghai Engineering Research Center of High-Performance Medical Device Materials,China(No.20DZ2255500)the Project of Creation of Life Innovation Materials for Interdisciplinary and International Researcher Development,Tohoku University,sponsored by Ministry,Education,Culture,Sports,Science and Technology,Japan,and the Grant-in Aid for Scientific Research(C)(No.20K05139)from JSPS(Japan Society for the Promotion of Science),Tokyo,Japan.
文摘Zr was added to Ti−Nb−Fe alloys to develop low elastic modulus and high strengthβ-Ti alloys for biomedical applications.Ingots of Ti−12Nb−2Fe−(2,4,6,8,10)Zr(at.%)were prepared by arc melting and then subjected to homogenization,cold rolling,and solution treatments.The phases and microstructures of the alloys were analyzed by optical microscopy,X-ray diffraction,and transmission electron microscopy.The mechanical properties were measured by tensile tests.The results indicate that Zr and Fe cause a remarkable solid-solution strengthening effect on the alloys;thus,all the alloys show yield and ultimate tensile strengths higher than 510 MPa and 730 MPa,respectively.Zr plays a weak role in the deformation mechanism.Further,twinning occurs in all the deformed alloys and is beneficial to both strength and plasticity.Ti−12Nb−2Fe−(8,10)Zr alloys with metastableβphases show low elastic modulus,high tensile strength,and good plasticity and are suitable candidate materials for biomedical implants.
基金Project(51801129)supported by the National Natural Science Foundation of ChinaProject supported by the State Key Laboratory of Powder Metallurgy,China。
文摘Ab initio calculations are used to understand the fundamental mechanism of the solid solution softening/hardening of the Mo-binary system.The results reveal that the Mo-Ti,Mo-Ta,Mo-Nb,and Mo-W interactions are primarily attractive with negative heats of formation,while the interactions of Mo-Re,and Mo-Zr would be mainly repulsive with positive heats of formation.It is also shown that the addition of Re and Zr would cause the solid solution softening of Mo by the decrease of the unstable stacking fault energy and the increase of ductility.On the contrary,the elements of W,Ta,Ti,and Nb could bring about the solid-solution hardening of Mo through the impediment of the slip of the dislocation and the decrease of ductility.Electronic structures indicate that the weaker/stronger chemical bonding due to the alloying elements should fundamentally induce the solid solution softening/hardening of Mo.The results are discussed and compared with available evidence in literatures,which could deepen the fundamental understanding of the solid solution softening/hardening of the binary metallic system.
基金supported by the National Natural Science Foundation of China(52071218)Shenzhen Science and Technology Innovation Commission(20200731215211001 and 20200814110413001)Guangdong Basic and Applied Basic Research Foundation(2022A1515012492)。
