Mg和Cu含量对Al-Si-Mg系合金组织和性能的影响

Influence of Mg and Cu Content on Microstructure and Properties of Al-Si-Mg Series Alloys

采用光学显微镜、扫描电子显微镜和拉伸试验机研究了Mg、Cu含量变化对AlSi-Mg系合金T6态组织与性能的影响。结果表明:随着Mg含量的增加,合金的二次枝晶臂间距减小,Mg_2Si强化相增多,起到固溶强化的作用。随着Cu含量的增加,共晶Si由片状逐渐转变成细小弥散分布的球状,且大小不一; Al_2Cu强化相所形成的铝基固溶体对合金起到了固溶强化作用。当Mg的质量分数为0. 5%～0. 6%,Cu的质量分数为0. 3%～0. 5%时,Al-Si-MgCu系合金具有相对较好的力学性能,其抗拉强度达到350. 9 MPa,屈服强度达到304. 4 MPa,断后伸长率为6. 96%,断裂特征为典型韧窝断口的塑性断裂。

Effect of Mg and Cu contents on microstructure and mechanical properties of Al-Si-Mg series alloys in T6 state was studied by means of optical microscope,scanning electron microscopy(SEM)and tensile tester.The results showed that with the increase of Mg content,the secondary dendrite arm spacing of alloy decreased and the amount of strengthening phase of Mg 2Si increased,which played a role of solid solution strengthening.With the increase of Cu content,the eutectic Si morphology gradually changed from lamellar to spherical with fine dispersion and varying in size.Aluminum-based solid solution formed by strengthening phase of Al 2Cu played a solid solution strengthening role in the alloy.When the mass fraction of Mg was in the range of 0.5%to 0.6%and that of Cu was in the range of 0.3%to 0.5%,the Al-Si-Mg-Cu series alloys had relatively good mechanical properties,it’s tensile strength was 350.9 MPa,yield strength was 304.4 MPa,elongation was 6.96%,and the fracture was characterized by plastic fracture of typical dimple fracture.