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采用重力铸造法制备Mg-8Al-8Zn-xSi(x=1,2,4,质量分数)镁合金。研究了不同Si含量对合金显微组织及室温和高温(150℃)力学性能的影响。结果表明:合金主要由α-Mg基体、β-Mg_(17)Al_(12)、Mg_2Si和MgZn相组成。随着Si含量的增加,Mg_2Si颗粒由汉字状逐渐转变为粗大的骨骼状。Si含量从1%增加到2%和4%时,Mg_2Si颗粒的平均尺寸由25μm分别增大到30μm和150μm;合金的硬度逐渐提高;其室温及高温抗拉强度、屈服强度和伸长率均呈现先提高后下降的趋势;室温及高温拉伸断裂形式为准解理脆性断裂。
Mg-8Al-8Zn-xSi (x = 1, 2, 4, mass fraction) magnesium alloy was prepared by gravity casting. The effects of different Si contents on the microstructure and mechanical properties at room temperature and high temperature (150 ℃) were investigated. The results show that the alloy consists of α-Mg matrix, β-Mg_ (17) Al_ (12), Mg_2Si and MgZn phases. With the increase of Si content, Mg_2Si particles gradually changed from kanji to coarse bone. When the content of Si increased from 1% to 2% and 4%, the average size of Mg_2Si particles increased from 25μm to 30μm and 150μm, respectively. The hardness of the alloy increased gradually. The tensile strength, yield strength and elongation at room temperature and high temperature all showed First increase and then decrease the trend; room temperature and high temperature tensile fracture mode quasi-cleavage brittle fracture.