变质处理及挤压铸造对过共晶Al-Si-Cu-Mg合金组织与性能的影响

摘要

研究了Sr、Sr-P变质处理对过共晶Al-Si-Cu-Mg合金组织和性能的影响.测试合金的力学性能并观察显微组织,分析变质处理对合金组织和力学性能的影响.结果发现:对重力铸造合金进行变质处理时,Sr的加入使合金组织中的粗大片状共晶Si变为细小的纤维状,随着P的加入,粗大多角的块状初生Si变为细小的粒状,合金硬度、 抗拉强度及伸长率明显提高;对挤压铸造合金进行变质处理时,Sr的加入使合金组织中的粗大片状共晶Si变为细小的纤维状,而随着P的加入原本挤压铸造时细小块状的初生Si反而长大,合金的抗拉强度及伸长率明显降低,主要是形成的Al-Sr-P影响了变质效果.对于挤压铸造,合金的最佳处理工艺为Sr变质,不加P.%This paper mainly studies the effects of Sr and Sr-P modification on the microstructure and properties of the hypereutectic Al-Si-Cu-Mg alloy. The mechanical properties of the alloy are tested and the microstructure of the alloy is observed, and the effect of the modification on microstructure and mechanical properties of alloy is analyzed. The results show that in the modification of the cast alloy, the coarse flake eutectic Si in the alloy is changed into the tiny fibrous with the addition of Sr, and the large primary Si is changed into the fine granular with the addition of P, thus, the hardness, tensile strength and elongation of the alloy are obviously increased. In the modification of the squeeze casting alloy, the coarse flake eutectic Si in the alloy is changed into the tiny fibrous with the addition of Sr, but fine block primary Si in the squeeze casting has grown up, and the tensile strength and elongation of the alloy decreased obviously. It is mainly that the formation of Al-Sr-P has weakened the effect of modification. The best treatment process for the alloy is the squeeze casting after Sr modification treatment in the alloys without P addition.