Al含量对Mg-xAl-1Zn-1Si合金组织与力学性能的影响

Effects of Al Concentration on Microstructure and Mechanical Properties of Mg-xAl-1Zn-1Si Alloy

研究了Al含量对Mg-x Al-1Zn-1Si(x=4,6,8,wt%)合金显微组织和力学性能的影响。结果表明,合金主要由α-Mg、β-Mg17Al12和Mg2Si相组成。随着Al含量的增加,α-Mg基体晶粒尺寸先减小后增大;呈网状分布于晶界上的Mg17Al12相的体积分数逐渐增大;Mg2Si相由原来粗大的汉字状逐渐转变为相对细小的杆状。Al含量从4%增加到6%和8%时,α-Mg基体晶粒的平均尺寸分别为30、20和40μm,合金硬度逐渐提高;其室温与150℃抗拉强度、屈服强度和伸长率先升高后下降;合金拉伸断裂形式为准解理脆性断裂。

The effects of A1 content on the microstructure and mechanical properties of alloys Mg-xAl-lZn-lSi （x=4, 6, 8, wt%） were studied. The results show that the microstructure of as-cast Mg-xAl-1Zn-1Si consists of α-Mg matrix, β-Mg17Al12 phase and Mg2Si phase. The average grain size of α-Mg matrix decreases first and then increases with increase of Al content. Moreover, the volume fi＇action of β-Mg-Mg17Al12 phase decreases and the coarse Chinese script type Mg2Si particles becomes fine bacilliform. The average grain size of α-Mg matrix are 30, 20and 40 μm respectively with the increase of Al content from 4% to 6% and 8%, while the hardness of the alloys increases gradually. The ultimate tensile strength, yield strength and elongation of alloys increases with the increase of A1 content from 4% to 6% at room temperature and 150℃ and then decreases when Al content is 8%. The fracture mechanism of the alloy is quasi-cleavage brittle fracture.