Cu-0.81Cr-0.12Zr-0.05La-0.05Y(mass fraction) alloy was successively subjected to hot rolling, solid solution treatment, cold rolling and aging treatments. Its microstructure, microhardness and electrical conductivity ...Cu-0.81Cr-0.12Zr-0.05La-0.05Y(mass fraction) alloy was successively subjected to hot rolling, solid solution treatment, cold rolling and aging treatments. Its microstructure, microhardness and electrical conductivity at different states were systematically investigated. The as-cast microstructure consists of three phases: Cu matrix, Cr and Cu5 Zr. Zr is completely dissolved into the matrix while partial Cr remains after the solid solution treatment. Aging of the cold-rolled sample makes nanocrystals of Cr and Cu5 Zr precipitate from the matrix, and the microhardness and electrical conductivity rise. A combination of high microhardness(HV 186) and high conductivity(81% IACS) can be obtained by aging the sample at 773 K for 60 min. As the aging temperature increases, the orientation degree of the Cu crystals gradually decreases to zero, but the microstrain in them cannot be eliminated completely owing to the presence of precipitates and dislocations. The Cr precipitates exhibit the N-W orientation relationship with the matrix when the coherence strengthening mechanism plays a main role.展开更多
Pre-cold rolling with low reductions(<3%)was used to improve the mechanical properties of rolled ZK60 plates.The effects of rolling path on mechanical properties were investigated in detail.Both pre-cold rolling al...Pre-cold rolling with low reductions(<3%)was used to improve the mechanical properties of rolled ZK60 plates.The effects of rolling path on mechanical properties were investigated in detail.Both pre-cold rolling along the transverse direction(TD)and pre-cold rolling along the normal direction(ND)can increase the yield strength.However,pre-cold rolling along the TD is more effective than pre-cold rolling along the ND in improving the comprehensive mechanical properties.After pre-cold rolling to 3%reduction,the sample rolled along the TD and the sample rolled along the ND have similar tensile yield strength(~270 MPa).However,the former has a higher compressive yield strength,lower yield asymmetry and larger toughness than the latter.Moreover,pre-cold rolling can also enhance precipitation hardening effect.However,aging treatment cannot further improve the yield strength of pre-cold rolled samples.Finally,the related mechanism is discussed.展开更多
While pre-deformation is often conducted before aging treatment to increase the strength and microhardness of 2195 Al-Li alloy, it often increases the fatigue crack growth(FCG) rate and thus reduces the fatigue life o...While pre-deformation is often conducted before aging treatment to increase the strength and microhardness of 2195 Al-Li alloy, it often increases the fatigue crack growth(FCG) rate and thus reduces the fatigue life of the alloy.To determine the effects and causes of pre-deformation and heat treatment on the mechanical properties and FCG rate of2195 Al-Li alloy, and to provide a suitable calculation model for the FCG rate under different pre-deformation conditions, 2195 Al-Li alloy specimens with different degrees of pre-rolling(0, 3%, 6%, and 9%) were investigated. The experimental results indicate that with the increase of pre-rolling, the density of the T1phase and the uniformity of the S′distribution and the microhardness, tensile strength, and yield strength of the alloy increase and at the same time the FCG rate increases, and thus the fatigue life is reduced. It was also found that the normalized stress intensity factor of elastic modulus(E) can be applied to correlate the FCG rate of pre-rolled 2195 Al-Li alloy with constant C and K parameters.展开更多
A ring-shaped Mg?8.5 Gd?4 Y?1 Zn?0.4 Zr(wt%) alloy was manufactured via centrifugal casting and ring-rolling process. The effects of accumulative ring-rolling reduction amount on the microstructure, texture, and tensi...A ring-shaped Mg?8.5 Gd?4 Y?1 Zn?0.4 Zr(wt%) alloy was manufactured via centrifugal casting and ring-rolling process. The effects of accumulative ring-rolling reduction amount on the microstructure, texture, and tensile properties of the alloy were investigated. The results indicate that the microstructure of centrifugal cast alloy consists of equiaxed grains and network-like eutectic structure present at grain boundaries. The ring-rolled alloy exhibits a characteristic bimodal microstructure composed of fine dynamic recrystallized(DRXed) grains with weak basal texture and coarse un-DRXed grains with strong basal texture, along with the presence of LPSO phase. With increasing amount of accumulative ring-rolling reduction, the coarse un-DRXed grains are refined via the formation of increasing amount of fine DRXed grains. Meanwhile, the dynamic precipitation of Mg5 RE phase occurs, generating a dispersion strengthening effect. A superior combination of strength and ductility is achieved in the ring-rolled alloy after an accumulative rolling reduction of 80%. The tensile strength of this ring-rolled alloy after peak aging is further enhanced, reaching 511 MPa, while keeping a reasonable ductility. The salient strengthening mechanisms identified include the grain boundary strengthening of fine DRXed grains, dispersion strengthening of dynamic precipitated Mg;RE phase, short fiber strengthening of LPSO lamellae/rods, and precipitation strengthening of nano-sized prismatic β precipitates and basal γ precipitates.展开更多
基金Project(51227001)supported by the National Natural Science Foundation of ChinaProject(2011CB610405)supported by the National Basic Research Program of China
文摘Cu-0.81Cr-0.12Zr-0.05La-0.05Y(mass fraction) alloy was successively subjected to hot rolling, solid solution treatment, cold rolling and aging treatments. Its microstructure, microhardness and electrical conductivity at different states were systematically investigated. The as-cast microstructure consists of three phases: Cu matrix, Cr and Cu5 Zr. Zr is completely dissolved into the matrix while partial Cr remains after the solid solution treatment. Aging of the cold-rolled sample makes nanocrystals of Cr and Cu5 Zr precipitate from the matrix, and the microhardness and electrical conductivity rise. A combination of high microhardness(HV 186) and high conductivity(81% IACS) can be obtained by aging the sample at 773 K for 60 min. As the aging temperature increases, the orientation degree of the Cu crystals gradually decreases to zero, but the microstrain in them cannot be eliminated completely owing to the presence of precipitates and dislocations. The Cr precipitates exhibit the N-W orientation relationship with the matrix when the coherence strengthening mechanism plays a main role.
基金financially supported by the National Natural Science Foundation of China (No. 51601154)the Fundamental Research Funds for the Central Universities, China (No. XDJK2019B003)+1 种基金the Natural Science Foundation of Jiangsu Higher Education Institutions of China (No. 17KJD430006)Chongqing Municipal Education Commission, China (No. KJZDK202001502)
文摘Pre-cold rolling with low reductions(<3%)was used to improve the mechanical properties of rolled ZK60 plates.The effects of rolling path on mechanical properties were investigated in detail.Both pre-cold rolling along the transverse direction(TD)and pre-cold rolling along the normal direction(ND)can increase the yield strength.However,pre-cold rolling along the TD is more effective than pre-cold rolling along the ND in improving the comprehensive mechanical properties.After pre-cold rolling to 3%reduction,the sample rolled along the TD and the sample rolled along the ND have similar tensile yield strength(~270 MPa).However,the former has a higher compressive yield strength,lower yield asymmetry and larger toughness than the latter.Moreover,pre-cold rolling can also enhance precipitation hardening effect.However,aging treatment cannot further improve the yield strength of pre-cold rolled samples.Finally,the related mechanism is discussed.
基金Project(U21A20132) supported by the National Natural Science Foundation of ChinaProject(Gui Renzi2019(13))supported by the Guangxi Specially-invited Experts Foundation of Guangxi Zhuang Autonomous Region,China。
文摘While pre-deformation is often conducted before aging treatment to increase the strength and microhardness of 2195 Al-Li alloy, it often increases the fatigue crack growth(FCG) rate and thus reduces the fatigue life of the alloy.To determine the effects and causes of pre-deformation and heat treatment on the mechanical properties and FCG rate of2195 Al-Li alloy, and to provide a suitable calculation model for the FCG rate under different pre-deformation conditions, 2195 Al-Li alloy specimens with different degrees of pre-rolling(0, 3%, 6%, and 9%) were investigated. The experimental results indicate that with the increase of pre-rolling, the density of the T1phase and the uniformity of the S′distribution and the microhardness, tensile strength, and yield strength of the alloy increase and at the same time the FCG rate increases, and thus the fatigue life is reduced. It was also found that the normalized stress intensity factor of elastic modulus(E) can be applied to correlate the FCG rate of pre-rolled 2195 Al-Li alloy with constant C and K parameters.
基金financial support by Fundamental Research Funds for the National Key Research and Development Program of China(Project No.2016YFB0700403)the Venture&Innovation Support Program for Chongqing Overseas Returnees(Project No.cx2018057)+1 种基金the Chongqing Research Program of Basic Research and Frontier Technology(Project Nos.cstc2019jcyjmsxm0548 and cstc2019jcyj-msxm X0306)the Fundamental Research Funds for the Central Universities(Project No.2021CDJJMRH-001)。
文摘A ring-shaped Mg?8.5 Gd?4 Y?1 Zn?0.4 Zr(wt%) alloy was manufactured via centrifugal casting and ring-rolling process. The effects of accumulative ring-rolling reduction amount on the microstructure, texture, and tensile properties of the alloy were investigated. The results indicate that the microstructure of centrifugal cast alloy consists of equiaxed grains and network-like eutectic structure present at grain boundaries. The ring-rolled alloy exhibits a characteristic bimodal microstructure composed of fine dynamic recrystallized(DRXed) grains with weak basal texture and coarse un-DRXed grains with strong basal texture, along with the presence of LPSO phase. With increasing amount of accumulative ring-rolling reduction, the coarse un-DRXed grains are refined via the formation of increasing amount of fine DRXed grains. Meanwhile, the dynamic precipitation of Mg5 RE phase occurs, generating a dispersion strengthening effect. A superior combination of strength and ductility is achieved in the ring-rolled alloy after an accumulative rolling reduction of 80%. The tensile strength of this ring-rolled alloy after peak aging is further enhanced, reaching 511 MPa, while keeping a reasonable ductility. The salient strengthening mechanisms identified include the grain boundary strengthening of fine DRXed grains, dispersion strengthening of dynamic precipitated Mg;RE phase, short fiber strengthening of LPSO lamellae/rods, and precipitation strengthening of nano-sized prismatic β precipitates and basal γ precipitates.