In order to improve the stress corrosion cracking resistance of the weldable Al Zn Mg alloys with medium strength, the near solvus pre precipitation following high temperature solution treatment was performed on LC52 ...In order to improve the stress corrosion cracking resistance of the weldable Al Zn Mg alloys with medium strength, the near solvus pre precipitation following high temperature solution treatment was performed on LC52 and 7039 aluminum alloys. The effect of the pre precipitation on the microstructure, age hardening and stress corrosion cracking of LC52 and 7039 alloy was investigated. The results show that the near solvus pre precipitation can be limited on grain boundary and can enhance the discontinuity of grain boundary precipitates. The stress corrosion cracking resistance of aged Al Zn Mg alloys can be improved with non deteriorated strength and plasticity via pre precipitation.展开更多
Al-Zn-Mg-Cu-Zr alloys containing Yb were prepared by cast metallurgy.Effect of 0.30% Yb additions on the microstructure and properties of 7A60 aluminum alloys with T6 and T77 aging treatments was investigated by TEM,o...Al-Zn-Mg-Cu-Zr alloys containing Yb were prepared by cast metallurgy.Effect of 0.30% Yb additions on the microstructure and properties of 7A60 aluminum alloys with T6 and T77 aging treatments was investigated by TEM,optical microscopy,hardness and electric conductivity measurement,tensile test and stress corrosion cracking test.The results show that the Yb additions to high strength Al-Zn-Mg-Cu-Zr aluminum alloys can produce fine coherent dispersoids.Those dispersoids can strongly pin dislocation and subgrain boundaries,which can significantly retard the recrystallization by inhibiting the nucleation of recrystallization and the growth of subgrains and keeping low-angle subgrain boundaries.Yb additions can obviously enhance the resistance to stress corrosion cracking and the fracture toughness property,and mildly increase the strength and ductility with T6 and T77 treatments.展开更多
The solidification paths of Al-Zn-Mg-Cu alloys and its precipitation behavior are analyzed using software package JMatPro 6.0 for material property simulation of Al-base alloys.The microstructures of the experimental ...The solidification paths of Al-Zn-Mg-Cu alloys and its precipitation behavior are analyzed using software package JMatPro 6.0 for material property simulation of Al-base alloys.The microstructures of the experimental alloys are analyzed;the experimental results of microstructural analysis are in agreement with the thermodynamic prediction.Through orthogonal experimental method,this paper designs the composition of Al-Zn-Mg-Cu alloys by studying the variation of η(MgZn2) phase,S(Al2CuMg) phase,T(AlZnMgCu) phase amount and precipitation temperatures with different Zn,Mg and Cu contents.It is found that with the optimum mass fraction of Zn of 6.7%,Mg of 2.2%-2.5% and Cu of 1.6%-2.0%,the mass fraction of η phase can be up to 8.7%-9.22% and that of S phase and T phase can be lower than 0.5%.展开更多
文摘In order to improve the stress corrosion cracking resistance of the weldable Al Zn Mg alloys with medium strength, the near solvus pre precipitation following high temperature solution treatment was performed on LC52 and 7039 aluminum alloys. The effect of the pre precipitation on the microstructure, age hardening and stress corrosion cracking of LC52 and 7039 alloy was investigated. The results show that the near solvus pre precipitation can be limited on grain boundary and can enhance the discontinuity of grain boundary precipitates. The stress corrosion cracking resistance of aged Al Zn Mg alloys can be improved with non deteriorated strength and plasticity via pre precipitation.
基金Project(50471057)supported by the National Natural Science Foundation of ChinaProject(2005CB623704)supported by the National Basic Research Program of China+1 种基金Project(NCET-04-0753)supported by the New Century Talented Professionals Program of Education Ministry,ChinaProject supported by the Key Lab of National Defense,China
文摘Al-Zn-Mg-Cu-Zr alloys containing Yb were prepared by cast metallurgy.Effect of 0.30% Yb additions on the microstructure and properties of 7A60 aluminum alloys with T6 and T77 aging treatments was investigated by TEM,optical microscopy,hardness and electric conductivity measurement,tensile test and stress corrosion cracking test.The results show that the Yb additions to high strength Al-Zn-Mg-Cu-Zr aluminum alloys can produce fine coherent dispersoids.Those dispersoids can strongly pin dislocation and subgrain boundaries,which can significantly retard the recrystallization by inhibiting the nucleation of recrystallization and the growth of subgrains and keeping low-angle subgrain boundaries.Yb additions can obviously enhance the resistance to stress corrosion cracking and the fracture toughness property,and mildly increase the strength and ductility with T6 and T77 treatments.
文摘The solidification paths of Al-Zn-Mg-Cu alloys and its precipitation behavior are analyzed using software package JMatPro 6.0 for material property simulation of Al-base alloys.The microstructures of the experimental alloys are analyzed;the experimental results of microstructural analysis are in agreement with the thermodynamic prediction.Through orthogonal experimental method,this paper designs the composition of Al-Zn-Mg-Cu alloys by studying the variation of η(MgZn2) phase,S(Al2CuMg) phase,T(AlZnMgCu) phase amount and precipitation temperatures with different Zn,Mg and Cu contents.It is found that with the optimum mass fraction of Zn of 6.7%,Mg of 2.2%-2.5% and Cu of 1.6%-2.0%,the mass fraction of η phase can be up to 8.7%-9.22% and that of S phase and T phase can be lower than 0.5%.
