Pb及时效处理对压铸AZ81镁合金组织和中温力学性能的影响

发布时间：2019-02-12 22:01

【摘要】：分别向AZ81镁合金熔液中加入0.5%,1.0%,1.5%(质量分数)的Pb,压铸成型并进行时效热处理,然后对其微观组织和180℃拉伸性能进行了研究。结果显示:Pb对压铸态AZ81的微观组织有一定的晶粒细化作用,且随着Pb加入量的增加,晶粒细化作用有一定的增加趋势;Pb主要以固溶形式存在于压铸态AZ81镁合金的α-Mg基体和β-Mg17Al12相中;时效后,Pb在压铸AZ81镁合金中依然主要以固溶形式存在,在α-Mg晶内和晶界上均有Mg17Al12相析出,Pb可在一定程度上抑制晶界上的不连续析出并促进晶内连续析出;180℃拉伸结果显示,随着Pb加入量的增多,各成分未时效试样的抗拉强度变化幅度不大,含Pb时效态试样中温抗拉强度随Pb含量增加呈上升趋势,最高平均强度为181 MPa,含Pb试样时效态抗拉强度比同成分未时效态均有所提高;各试样时效态屈服强度均比未时效态高;Pb元素和时效热处理均使压铸AZ81镁合金延伸率下降;时效使AZ81镁合金倾向于脆性断裂,塑性下降。
[Abstract]:The microstructures and tensile properties of AZ81 magnesium alloys were studied by adding 0.5 and 1.0% (mass fraction) Pb, die-casting and aging heat treatment respectively to the molten solution of AZ81 magnesium alloys. The results show that Pb has a certain grain refinement effect on the microstructure of die-cast AZ81, and with the increase of Pb content, the grain refinement has a certain increasing trend. Pb mainly exists in 伪-Mg matrix and 尾-Mg17Al12 phase of die-cast AZ81 magnesium alloy in the form of solid solution. After aging, Pb still exists in the form of solid solution in die-cast AZ81 magnesium alloy, and there is Mg17Al12 phase precipitation in 伪-Mg crystal and grain boundary. Pb can restrain discontinuous precipitation at grain boundary to some extent and promote continuous precipitation within grain boundary. The tensile results at 180 鈩，

本文编号：2420833