热处理制度对含Ag的7055铝合金断裂特征的影响

研究了含Ag7055铝合金在T6，T73，RRA3种热处理状态下的力学性能、断裂特征及显微组织变化特征。实验结果表明，RRA处理可以在保持T6状态强度的同时，获得较高的电导率，然而试样的延伸率相对较低；断口SEM形貌观察表明，T6状态断裂机制为剪切型穿晶断裂和沿晶断裂同时并存，而T73处理后，主要呈韧窝型穿晶断裂，沿晶断裂部分减少，RRA试样断口则主要为沿晶断裂，并在晶界面上分布有韧窝型断裂特征；由于不同热处理状态下，强化相不同且其阻碍位错滑移能力也不同，同时晶界PFZ宽度也发生变化，这些因素的综合作用导致不同热处理状态下的断裂特征不同。

Influence of Heat Treatment Regime on Microstructures and Fracture Characteristics of 7055 Al Alloy Containing Ag

Tensile properties, fracture characteristics and microstructures of 7055 aluminum alloy containing Ag in the T6, T73 and RRA conditions were investigated. The results of the investigations show that RRA treatment retains the strength of 7055-T6 with a higher electrical conductivity close to that of 7055-T73, but its elongation decreases greatly; SEM fractographs reveal that intergranular cracking and shear-type transgranular cracking were both present on the fracture appearance of 7055-T6 specimen. After T73 treatment, the fractographs consist of dimple-type transgranular cracking with minor intergranular cracking. With 7055-RRA specimen, intergranular cracking dominates with minor dimples distributed on the fracture surface. The types and volume fraction of precipitates, width of PFZ (Precipitate Free Zones ) and the ability of precipitates to impede dislocations varied with heat treatment regimes.