Cu对稀土A356合金组织及力学性能的影响

Effects of Cu on Microstructure and Mechanical Properties of Rare Earth Microalloying A356 Alloy

采用金相显微镜、扫描电镜、能谱仪、X射线衍射和万能电子拉伸试验机等手段,研究了稀土微合金化A356合金添加Cu后的显微组织和力学性能。结果表明,Cu对提高A356合金的强度具有显著的效果,不但细化了合金组织中的α-Al相,且使共晶Si由棒状转变为细小圆整的颗粒状,弥散分布在α-Al相晶界上。添加2.5%的Cu后A356合金力学性能最佳,抗拉强度、屈服强度及伸长率分别为322 MPa,235 MPa和4.6%,相比未添加Cu的A356合金分别提高了10.35%、26.82%和降低了21.5%。

The effects of Cu on microstructure and mechanical properties of rare earth microalloying A356 alloy were investiagted by using Metalloscope, SEM, EDS, XRD and tensile testing machine. The results indicate that Cu has a significant effect on improving the strength of rare earth microalloying A356 alloy. Cu could not only refine primary α-Al phase but also take the transformation from rodlike struc- ture to small round granular Si with diepersedly distributed on the grain boundary of α-Al phase. With 2.5% Cu addition, the tensile strength, yield strength and elongation of the alloy reach 235 MPa, 322 MPa and 4.6%, respectively, which increased by 10.35%, 26.82% and decreased by 21.5% compared with those of the alloy without Cu.