Er和Sr共同作用对A356铝合金显微组织与力学性能的影响

Combining effect of Er and Sr on the microstructure and mechanical properties of the as-casted A356 alloy

摘要:

通过制备Al-10Er-5Sr合金，并研究其微观组织及相组成，来研究Er和Sr共同作用对A356铝合金微观组织与力学性能的影响。根据加入Al-10Er-5Sr合金合金后A356铝合金微观组织和力学性能的变化，确定了Al-10Er-5Sr合金在A356铝合金中最佳含量。实验结果显示：Al-10Er-5Sr合金主要由α-Αl相、Al4Sr和Al3Er相组成。另外，A356铝合金中添加0.6%的Al-10Er-5Sr合金展现出最佳的显微组织结构和力学性能，合金二次枝晶臂间距减小到20.2um，针状的共晶硅相转变成纤维状。由于加入了0.6%的Al-10Er-5Sr合金，合金显微组织结构的改善，使得合金抗拉强度达到203.5MPa。与未经处理的A356铝合金相比，力学性能得到明显提升。最后，对合金晶粒细化和变质机理进行了分析讨论。

Abstract:

In order to investigate the combing effect of Er and Sr on the microstructure and mechanical properties of A356 alloy, Al-10Er-5Sr master alloy was fabricated and its microstructure and phase compositions were investigated. The optimal percentage of Al-10Er-5Sr in A356 alloy was obtained according to the evolution of microstructure and mechanical properties. The results showed that α-Al, Al4Sr and Al3Er were the main phases in Al-10Er-5Sr. In addition, the aluminum alloy with 0.6 wt% Al-10Er-5Sr exhibited optimal microstructure and mechanical properties, with the secondary dendrite arm spacing (SDAS) decreasing to 20.2 μm and acicular-like eutectic silicon transforming to fibrous. Due to the improved microstructure, the ultimate tensile strength of the alloy (with 0.6wt% Al-10Er-5Sr) increased to 203.5 MPa, which are much better than that of untreated A356 aluminum alloy. Finally, the grain refinement and modification mechanisms were discussed.