Yb对A356铝合金显微组织与力学性能的影响

Effects of Yb Addition on Microstructure and Mechanical Properties of A356 Aluminum Alloys

采用光学显微镜、扫描电镜等研究了稀土Yb对A356铝合金显微组织与力学性能的影响。结果表明,Yb显著细化了A356合金中α-Al的晶粒尺寸,二次枝晶间距从41μm减小到30μm。共晶Si组织由粗大的针状或板条状细化为纤维状。添加Yb的A356铝合金中生成了一种新的AlSiYb金属间化合物。随着Yb含量的增加,A356铝合金的力学性能先增大后减小,当Yb含量为0.2%时,合金的力学性能达到最大值,其抗拉强度为195 MPa,伸长率为4.8%。

Effects of rare earth Yb addition on microstructure and mechanical properties of A356 aluminum alloys were investigated by optical microscope,SEM.The results reveal that theα-Al grains in the A356 aluminum alloys can be refined by addition of the rare earth Yb.Secondary dendrite arm spacing in the A356 alloys modified with different Yb content is reduced from 41μm to 30μm.Eutectic Si phase is transformed from accicular and lath-like into fibrous ones.AlSiYb intermetallic compound can be observed in the 0.2% Yb modified alloy.Mechanical properties of the as-cast A356 aluminum alloy are increased firstly and then decreased with increasing in Yb content.With Yb content of 0.2%,the ultimate tensile strength and elongation of the alloy reach 195 MPa and 4.8%,respectively.