The precipitation behaviours of Al3Zr precipitate in the Al-Cu-Zr and Al-Cu-Zr-Ti-V alloys were studied by transmission electron microscopy. Metastable Al3Zr precipitates are homogeneously nucleated in dendrite centre...The precipitation behaviours of Al3Zr precipitate in the Al-Cu-Zr and Al-Cu-Zr-Ti-V alloys were studied by transmission electron microscopy. Metastable Al3Zr precipitates are homogeneously nucleated in dendrite centres resulting in homogeneous distribution. However, the precipitation in the interdendritic regions is complex and the precipitation morphologies, helical-like and stripe-like shapes, were observed, which are composed of many spherical Al3Zr precipitates. The stripe-like precipitate clusters have preferential orientations along with the -100- Al directions, which is inferred to be related to θ′（Al2Cu） and θ phases. Addition of Cu can accelerate the L12→D023 structural transformation of the Al3Zr precipitate.展开更多
The effect of homogenization on the hardness,tensile properties,electrical conductivity and microstructure of as-cast Al-6Mg-0.4Mn-0.25Sc-0.12Zr alloy was studied.The results show that during homogenization as-cast st...The effect of homogenization on the hardness,tensile properties,electrical conductivity and microstructure of as-cast Al-6Mg-0.4Mn-0.25Sc-0.12Zr alloy was studied.The results show that during homogenization as-cast studied alloy has obviously hardening effect that is similar to aging hardening behavior in traditional Al alloys.The precipitates are mainly Al3(Sc,Zr)and Al6Mn.When homogenization temperature increases the hardness peak value is declined and the time corresponding to hardness peak value is shortened.The electrical conductivity of the alloy monotonously increases with increasing homogenization temperature and time.The decomposition of the supersaturated solid solution containing Sc and Zr which is formed during direct chilling casting and the precipitation of Al3(Sc,Zr)cause hardness increasing.The depletion of the matrix solid solubility decreases the ability of electron scattering in the alloy,resulting in the electrical conductivity increased.Tensile property result at hot rolling state shows that the optimal homogenization treatment processing is holding at 300-350 ℃ for 6-8 h.展开更多
Effects of intermediate annealing temperature and time after hot working on recrystallization temperature （Tr） of Al-Mg-Sc-Zr alloy subjected to further cold working were investigated. It was found that Tr of cold w...Effects of intermediate annealing temperature and time after hot working on recrystallization temperature （Tr） of Al-Mg-Sc-Zr alloy subjected to further cold working were investigated. It was found that Tr of cold worked alloy dropped with the rise of intermediate annealing temperature or extension of annealing time, clue to coarsening of Al3（Sc, Zr） particles during intermediate annealing. After annealed at 550℃ for 1 h or 475℃ for 50 h, Tr is nearly same as that in a Sc, Zr free 5A06 alloy. Coarsening mechanism was also discussed. After hot rolling, residual dislocations promoted diffusion of Sc and Zr atoms at the elevated temperature of the intermediate annealing. Easier diffusion sped the growth of the AI3（Sc, Zr） particles, resulting in a coherency loss and quantity reduction of the particles.展开更多
基金Project (CDJZR12130048) supported by the Fundamental Research Funds for the Central Universities, ChinaProject supported by a Grant from the French Norwegian Foundation for Scientific and Technological Research and Industrial Development
文摘The precipitation behaviours of Al3Zr precipitate in the Al-Cu-Zr and Al-Cu-Zr-Ti-V alloys were studied by transmission electron microscopy. Metastable Al3Zr precipitates are homogeneously nucleated in dendrite centres resulting in homogeneous distribution. However, the precipitation in the interdendritic regions is complex and the precipitation morphologies, helical-like and stripe-like shapes, were observed, which are composed of many spherical Al3Zr precipitates. The stripe-like precipitate clusters have preferential orientations along with the -100- Al directions, which is inferred to be related to θ′（Al2Cu） and θ phases. Addition of Cu can accelerate the L12→D023 structural transformation of the Al3Zr precipitate.
基金Project(2005CB623705-01) supported by the National Key Fundamental Research and Development Program of ChinaProject(MKPT-2004-16ZD) supported by the National 10th Five-Year Plan Program
文摘The effect of homogenization on the hardness,tensile properties,electrical conductivity and microstructure of as-cast Al-6Mg-0.4Mn-0.25Sc-0.12Zr alloy was studied.The results show that during homogenization as-cast studied alloy has obviously hardening effect that is similar to aging hardening behavior in traditional Al alloys.The precipitates are mainly Al3(Sc,Zr)and Al6Mn.When homogenization temperature increases the hardness peak value is declined and the time corresponding to hardness peak value is shortened.The electrical conductivity of the alloy monotonously increases with increasing homogenization temperature and time.The decomposition of the supersaturated solid solution containing Sc and Zr which is formed during direct chilling casting and the precipitation of Al3(Sc,Zr)cause hardness increasing.The depletion of the matrix solid solubility decreases the ability of electron scattering in the alloy,resulting in the electrical conductivity increased.Tensile property result at hot rolling state shows that the optimal homogenization treatment processing is holding at 300-350 ℃ for 6-8 h.
基金support by the Innovation Foundationof Chinese Academy of Sciences (Grant No CXJJ-205)
文摘Effects of intermediate annealing temperature and time after hot working on recrystallization temperature （Tr） of Al-Mg-Sc-Zr alloy subjected to further cold working were investigated. It was found that Tr of cold worked alloy dropped with the rise of intermediate annealing temperature or extension of annealing time, clue to coarsening of Al3（Sc, Zr） particles during intermediate annealing. After annealed at 550℃ for 1 h or 475℃ for 50 h, Tr is nearly same as that in a Sc, Zr free 5A06 alloy. Coarsening mechanism was also discussed. After hot rolling, residual dislocations promoted diffusion of Sc and Zr atoms at the elevated temperature of the intermediate annealing. Easier diffusion sped the growth of the AI3（Sc, Zr） particles, resulting in a coherency loss and quantity reduction of the particles.
