Mg-12Al-12Zn-xSi合金的显微组织与力学性能

Microstructure and Mechanical Properties of Alloy Mg-12Al-12Zn-xSi

研究了Si含量对铸态Mg-12Al-12Zn-x Si(x=1,2,4;wt%)合金显微组织和力学性能的影响。结果表明,加入Si元素后,合金主要由α-Mg基体、β-Mg17Al12相、Mg2Si相和Mg2Zn11相组成;随Si含量从1%增加到4%,合金中的Mg2Si颗粒从少量的多边形块状、花瓣状转变为大量的多边形块状、条棒状,最后转变为多边形块状和粗大的骨骼状;且Si含量为2%时,Mg2Si相颗粒呈相对弥散分布;此时,合金的室温和高温抗拉强度、屈服强度和伸长率达到最大值。合金的室温拉伸断裂形式为准解理脆性断裂。

The effects of Si on the microstructures and mechanical properties of the alloys Mg-12Al-12Zn-xSi （x=1, 2, 4; wt%） were investigated. The results show ＇that the microstructure of the alloys consists of α-Mg matrix, phase β-Mg17Al12, Mg2Si and Mg2Zn11after adding Si. The morphology of Mg2Si particle in the alloys changes significantly from a few polygon and petal shapes to the lots of polygon and stick shapes, and finally to the polygon block and skeleton-like Shapes when the content- of Si increases from 1% to 4%. The Mg2Si particles distribute in the matrix dispersively when the Si content is 2%. And in the case, the room-temperature and elevated-temperature mechanical properties of the alloy can ＇reach the maximum. The room-temperature tensile fracture mechanism of the alloy is quasi-cleavage brittle fracture.