Mechanical properties and microstructures of Al-Li-Cu-Mg-Ag alloy after solution treatments were investigated by means of optical microscopy （OM）, tensile test, hardness measurement and electrical conductivity test,...Mechanical properties and microstructures of Al-Li-Cu-Mg-Ag alloy after solution treatments were investigated by means of optical microscopy （OM）, tensile test, hardness measurement and electrical conductivity test, differential scanning calorimetric （DSC）, energy dispersive X-ray （EDX）, scanning electron microscopy （SEM） and transition electron microscopy （TEM）, respectively The results show that both tensile strength and hardness increase first and then decrease with temperature at constant holding time of 30 min with maximum strength and hardness appearing at 520 ℃. Tensile strength, hardness and elongation of samples treated at 520 ℃ for 30 min are 566 MPa （σb）, 512 MPa （σ0.2）, HB 148 and 8.23% （δ）, respectively. There are certain amount of fine T1 （AI2CuLi） phase dispersing among AI substrates according to TEM images. This may result in mixed fracture morphology with trans-granular and inter-granular delamination cracks observed in SEM images.展开更多
The effects of solution treatment temperature and holding time on the microstructure and mechanical properties of extruded Al-6.02 wt.%Zn-1.94 wt.%Mg alloy were investigated by differential scanning calorimetry(DSC),o...The effects of solution treatment temperature and holding time on the microstructure and mechanical properties of extruded Al-6.02 wt.%Zn-1.94 wt.%Mg alloy were investigated by differential scanning calorimetry(DSC),optical microscopy(OM), scanning electron microscopy(SEM), X-ray diffraction(XRD), and tensile test. The results showed that the optimum solution treatment process for the alloy was 470 ℃, 2 h. The tensile strength, yield strength,and elongation of the samples after the aging treatment at 120℃ for 24 h were 486 MPa, 431 MPa, and 14.8%,respectively. The alloy produced more copious recrystallization with the augment of solution temperature and the extension of holding time. While the second phase of η(MgZn_(2)), and T(AlZnMgCu) in the matrix was not fully re-dissolved under the treatment condition of lower temperature or shorter holding time. Interestingly, the Zr aggregation was observed in the samples treated at 510 ℃ for 2 h, which led to the growth of the second phase particles and the increase of their area fraction.展开更多
V-5Cr-5Ti alloys have been fabricated using a laser melting deposition(LMD)additive manufacturing process,showing precipitates aggregated near the grain/dendrite boundaries.Since the mechanical properties of vanadium ...V-5Cr-5Ti alloys have been fabricated using a laser melting deposition(LMD)additive manufacturing process,showing precipitates aggregated near the grain/dendrite boundaries.Since the mechanical properties of vanadium alloys considerably depend on the precipitates,solution and aging treatments have been applied to eliminating the aggregations of the precipitates.The results show that as the solution temperature increases from 800 to 1560℃,the densities and the lengths of the precipitates are reduced,while the widths of the precipitates are increased.When the solution temperature reaches 1560℃,most impurity elements diffuse into the matrix and form into a nearly uniform supersaturated solid solution.Aging treatments have been applied to the 1560℃solution treated samples.It shows that as the aging temperature increases from 800 to 1200℃,the precipitate length increases,and the shapes of precipitates change from near-spherical to lath-like.Compared to 800 and 1200℃,aging at 1000℃results in the highest precipitate density.Compared to the LMD and solution-treated samples,the aged samples have the highest micro-hardness,due to the precipitation strengthening.展开更多
The effects of solution and ageing treatment (T6) on microstructure and tensile properties of as-extruded Mg-10Gd-3Y-0.6Zr (mass fraction. %) alloy were investigated. The results show that after T6 treatment, the diam...The effects of solution and ageing treatment (T6) on microstructure and tensile properties of as-extruded Mg-10Gd-3Y-0.6Zr (mass fraction. %) alloy were investigated. The results show that after T6 treatment, the diameter of grain increases to 20 μm. As the second phases dissolve into the matrix, the smaller and denser β′ phases precipitate inside the grains. After T6-treatment, both yield strength (TYS) and ultimate tensile strength (UTS) are increased. Comparing with that in only ageing condition (T5), the UTS and TYS increased from 365 MPa,285 MPa to 400 MPa,310 MPa, respectively, but the elongation decreased from 7.0% to 3.5%. It has been found that the effects of precipitates on the strength are stronger than that of the growth of grain size.展开更多
基金Foundation item： Project（6140506） supported by GAD （General Armament Department）, China
文摘Mechanical properties and microstructures of Al-Li-Cu-Mg-Ag alloy after solution treatments were investigated by means of optical microscopy （OM）, tensile test, hardness measurement and electrical conductivity test, differential scanning calorimetric （DSC）, energy dispersive X-ray （EDX）, scanning electron microscopy （SEM） and transition electron microscopy （TEM）, respectively The results show that both tensile strength and hardness increase first and then decrease with temperature at constant holding time of 30 min with maximum strength and hardness appearing at 520 ℃. Tensile strength, hardness and elongation of samples treated at 520 ℃ for 30 min are 566 MPa （σb）, 512 MPa （σ0.2）, HB 148 and 8.23% （δ）, respectively. There are certain amount of fine T1 （AI2CuLi） phase dispersing among AI substrates according to TEM images. This may result in mixed fracture morphology with trans-granular and inter-granular delamination cracks observed in SEM images.
基金Project(U1837207) supported by the National Natural Science Foundation of China。
文摘The effects of solution treatment temperature and holding time on the microstructure and mechanical properties of extruded Al-6.02 wt.%Zn-1.94 wt.%Mg alloy were investigated by differential scanning calorimetry(DSC),optical microscopy(OM), scanning electron microscopy(SEM), X-ray diffraction(XRD), and tensile test. The results showed that the optimum solution treatment process for the alloy was 470 ℃, 2 h. The tensile strength, yield strength,and elongation of the samples after the aging treatment at 120℃ for 24 h were 486 MPa, 431 MPa, and 14.8%,respectively. The alloy produced more copious recrystallization with the augment of solution temperature and the extension of holding time. While the second phase of η(MgZn_(2)), and T(AlZnMgCu) in the matrix was not fully re-dissolved under the treatment condition of lower temperature or shorter holding time. Interestingly, the Zr aggregation was observed in the samples treated at 510 ℃ for 2 h, which led to the growth of the second phase particles and the increase of their area fraction.
基金Project(51871203)supported by the National Natural Science Foundation of ChinaProject(TZ2018006-0303-02)supported by the Science Challenge Project,ChinaProjects(2020ZDZX0017,2019YFG0217)supported by the Sichuan Science and Technology Program,China。
文摘V-5Cr-5Ti alloys have been fabricated using a laser melting deposition(LMD)additive manufacturing process,showing precipitates aggregated near the grain/dendrite boundaries.Since the mechanical properties of vanadium alloys considerably depend on the precipitates,solution and aging treatments have been applied to eliminating the aggregations of the precipitates.The results show that as the solution temperature increases from 800 to 1560℃,the densities and the lengths of the precipitates are reduced,while the widths of the precipitates are increased.When the solution temperature reaches 1560℃,most impurity elements diffuse into the matrix and form into a nearly uniform supersaturated solid solution.Aging treatments have been applied to the 1560℃solution treated samples.It shows that as the aging temperature increases from 800 to 1200℃,the precipitate length increases,and the shapes of precipitates change from near-spherical to lath-like.Compared to 800 and 1200℃,aging at 1000℃results in the highest precipitate density.Compared to the LMD and solution-treated samples,the aged samples have the highest micro-hardness,due to the precipitation strengthening.
基金Project supported by program for Changjiang Scholars and Innovative Research Teamin University(IRT0713)National Basic Research Program ofChina (2007CB613702, 2007CB613701)
文摘The effects of solution and ageing treatment (T6) on microstructure and tensile properties of as-extruded Mg-10Gd-3Y-0.6Zr (mass fraction. %) alloy were investigated. The results show that after T6 treatment, the diameter of grain increases to 20 μm. As the second phases dissolve into the matrix, the smaller and denser β′ phases precipitate inside the grains. After T6-treatment, both yield strength (TYS) and ultimate tensile strength (UTS) are increased. Comparing with that in only ageing condition (T5), the UTS and TYS increased from 365 MPa,285 MPa to 400 MPa,310 MPa, respectively, but the elongation decreased from 7.0% to 3.5%. It has been found that the effects of precipitates on the strength are stronger than that of the growth of grain size.
