The tensile properties, electrical conductivity, and microstructure of the forged A1-7.1Zn-1.1Mg-1.6Cu-0.14Zr alloy were investigated after a two-step ageing treatment at 120 and 170℃. The results indicate that the s...The tensile properties, electrical conductivity, and microstructure of the forged A1-7.1Zn-1.1Mg-1.6Cu-0.14Zr alloy were investigated after a two-step ageing treatment at 120 and 170℃. The results indicate that the strength of the alloy reaches the peak value at 170~C for 1 h during the second step ageing and then decreases sharply. However, the electrical conductivity value increases continuously with the second ageing time increasing. The fracture mechanism of the alloy is intergranular fracture for 1 h and then changes to dimple transgranular fracture later, and the toughness of the alloy is improved significantly. The phases of rl＇ and 1＂1 are major precipitates in the alloy under the two-step ageing condition. Discontinuous grain boundary precipitates and precipitate-flee zones along the grain boundary are clearly observed.展开更多
Al-4.0Cu-1.4Mg-0.6Mn （2E12） and Al-4.0Cu-1.4Mg-0.6Mn-0.3Zr aluminum billets were manufactured by soft-contact electromagnetic continuous casting （EMC）. Subsequent forging and heat treatment were conducted and the ...Al-4.0Cu-1.4Mg-0.6Mn （2E12） and Al-4.0Cu-1.4Mg-0.6Mn-0.3Zr aluminum billets were manufactured by soft-contact electromagnetic continuous casting （EMC）. Subsequent forging and heat treatment were conducted and the effects of Zr on the microstructure and properties of the Al-4.0Cu-1.4Mg-0.6Mn alloy were studied. The results show that the addition of 0.3% Zr can reduce the dendrite and refine grains. During forging and solution treatment, fine and dispersive Al3Zr particles precipitated from the supersaturated α （Al） solid solution in the heating process of the billet can effectively pin dislocations and subgrain boundaries. Because of the addition of Zr, the mechanical properties are improved with the tensile strength, yield strength, elongation, and contraction of the area increasing by 5.4%, 11.3%, 9.7%, and 12.6%, respectively. Moreover, under the condition of R = 0.1, the fatigue crack growth rate （da/dN） of the Al-4.0Cu-1.4Mg-0.6Mn-0.3Zr alloy is lower than that of the Al-4.0Cu-1.4Mg-0.6Mn alloy.展开更多
基金supported by the Sub-project of Major State Basic Research Development Program of China (No 2005CB623705)the National Natural Science Foundation of China (No 50875031)
文摘The tensile properties, electrical conductivity, and microstructure of the forged A1-7.1Zn-1.1Mg-1.6Cu-0.14Zr alloy were investigated after a two-step ageing treatment at 120 and 170℃. The results indicate that the strength of the alloy reaches the peak value at 170~C for 1 h during the second step ageing and then decreases sharply. However, the electrical conductivity value increases continuously with the second ageing time increasing. The fracture mechanism of the alloy is intergranular fracture for 1 h and then changes to dimple transgranular fracture later, and the toughness of the alloy is improved significantly. The phases of rl＇ and 1＂1 are major precipitates in the alloy under the two-step ageing condition. Discontinuous grain boundary precipitates and precipitate-flee zones along the grain boundary are clearly observed.
文摘Al-4.0Cu-1.4Mg-0.6Mn （2E12） and Al-4.0Cu-1.4Mg-0.6Mn-0.3Zr aluminum billets were manufactured by soft-contact electromagnetic continuous casting （EMC）. Subsequent forging and heat treatment were conducted and the effects of Zr on the microstructure and properties of the Al-4.0Cu-1.4Mg-0.6Mn alloy were studied. The results show that the addition of 0.3% Zr can reduce the dendrite and refine grains. During forging and solution treatment, fine and dispersive Al3Zr particles precipitated from the supersaturated α （Al） solid solution in the heating process of the billet can effectively pin dislocations and subgrain boundaries. Because of the addition of Zr, the mechanical properties are improved with the tensile strength, yield strength, elongation, and contraction of the area increasing by 5.4%, 11.3%, 9.7%, and 12.6%, respectively. Moreover, under the condition of R = 0.1, the fatigue crack growth rate （da/dN） of the Al-4.0Cu-1.4Mg-0.6Mn-0.3Zr alloy is lower than that of the Al-4.0Cu-1.4Mg-0.6Mn alloy.
