Mg-6Al-1Zn-xSi合金的显微组织与高温力学性能

Microstructure and Elevated Mechanical Properties of Magnesium Alloys Mg-6Al-1Zn-xSi

采用重力铸造法制备了不同Si含量的Mg-6Al-1Zn-x Si合金,分析了合金的显微组织,测试了合金在150℃下的拉伸力学性能。结果表明,合金均由α-Mg基体、β-Mg17Al12和Mg2Si相组成。随着Si含量的增加,α-Mg基体晶粒的平均尺寸逐渐减小,Mg2Si颗粒的平均尺寸逐渐增大;β-Mg17Al12由分布于晶界及晶内的点状转变为网状分布于晶界上;合金的高温抗拉强度、屈服强度和伸长率逐渐提高。此外,高温拉伸断裂形式为准解理脆性断裂。

The alloys Mg-6Al-1Zn-x Si with different Si contents were prepared by gravity casting,and the microstructures of the alloy were analyzed and the elevated-temperature tensile properties at 150 ℃ were measured.The results show that the as-cast alloys consist of the phases α-Mg,β-Mg17Al12 and Mg2Si.With increasing the Si content,the average grain size of α-Mg matrix decreases but that of Mg2 Si increases gradually,while the distribution of the β-Mg17Al12 phase changes from spotted state at grain boundary and also grain interior to network shape at grain boundary.The elevated-temperature ultimate tensile strength,yield strength and elongation of the alloys increase gradually with the increase of Si content.Furthermore,the tensile fracture mechanism of the alloy is quasi-cleavage brittle fracture.