固溶处理温度对7A85航空铝合金微观组织及力学性能的影响

Influence of solution treatment temperature on microstructure and mechanical properties of 7A85 aerospace aluminum alloy

运用光学显微镜、扫描电镜和透射电镜研究了固溶处理温度对7A85铝合金微观组织和力学性能的影响。试验结果表明:随固溶温度的提高,7A85铝合金的屈服强度、抗拉强度和断裂韧性均先增大后减小,450℃时达到峰值,分别为624 MPa、679 MPa和38 MPa·m1/2;随固溶温度的升高,基体再结晶晶粒的尺寸增大,晶粒的均匀性相对提高,粗大第二相粒子含量降低,人工时效过程获得更多弥散析出的纳米强化相粒子;不同固溶处理后的断裂方式均为穿晶断裂和沿晶断裂的混合断裂机制,固溶温度越高,弥散韧窝越多。

Influence of solution treatment temperature on microstructure and mechanical properties of 7A85 aluminum was investigated by using OM,SEM and TEM.The results indicate that the yield strength,tensile strength and fracture toughness increase first,and then decrease with the increase of solution treatment temperature.The peak value arrives at 450℃and reaches 624 MPa,679 MPa and 38 MPa·m1/2,respectively.With the increase of solution treatment temperature,the grain size increases and the grain homogeneity is improved,while the fraction of coarse secondary phase decreases,and more nanometer strengthening phase particles dispersedly precipitated are obtained during artificial aging process.The fracture mechanism of the alloy after different solution treatments is all composed of transgranular fracture and intergranular fracture.The fraction of dispersoid dimples increases with the increase of solution treatment temperature.