时效制度对Al-7.1Zn-1.1Mg-1.6Cu-0.14Zr合金断裂行为的影响

通过拉伸性能测试及金相显微镜、扫描电镜和透射电镜分析对比研究了Al-7.1Zn-1.1Mg-1.6Cu-0.14Zr合金在T6与T74热处理状态下的力学性能、断裂行为和显微组织。结果表明:相对T6态,Al-7.1Zn-1.1Mg-1.6Cu-0.14Zr合金经T74处理后,强度降低了约15%,但延伸率和电导率分别增加了52%和29%。合金T6态的断裂方式为穿晶剪切和沿晶韧窝混合型断裂;经过T74处理的合金断裂方式为穿晶韧窝型断裂。不同热处理状态下,晶内和晶界组织对位错运动的共同作用是决定合金断裂行为的主要原因。

Influence of Aging Treatment Regime on Fracture Behavior of Al-7.1Zn-1.1Mg-1.6Cu-0.14Zr Alloy

Tensile properties, fracture behavior and microstructure of Al-7.1Zn-1.1Mg-1.6Cu-0.14Zr alloy with T6 and T74 aging treatments were investigated by tensile testing, optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that, compared with the values in T6 state, the strength of the alloy in T74 state decreases by 15%; however, the elongation and electrical conductivity of the alloy in T74 state increases by 52% and 29%, respectively. The fracture mode of the alloy in T6 state is transgranular shearing and intergranular dimple mixed fracture. In T74 state, the fracture mode of alloy is transgranular dimple fracture. The fracture behavior of the alloy with different aging treatments is mainly determined by the coordinating interaction between movement of the dislocation and microstructures in the grain and grain boundary