凝固条件和热处理及微量锶对一种Al-Si合金组织和性能的影响

Influence of Solidification Conditions,Heat Treatment and Strontium on the Microstructure and Mechanical Properties of an Industrial Al Si Cast Alloy

研究了凝固条件和热处理及微量锶对Ａ３５６合金组织与性能的影响。试验结果表明，锶的加入不仅对显微组织而且对合金中αＡｌ固溶体的弥散析出行为也有较大的改变，加入锶后的合金在冷却过程中（“隐形热处理”）的一次弥散相和随后热处理的二次弥散相都要比Ａ３５６合金细得多。这种细化作用较普通光学显微组织对力学性能的影响还要大。即使通过长时间的热处理，锶和冷却速度对显微组织的影响仍没有实质的变化。同时比较了定向凝固的Ａ３５６合金在铸态与热处理态下的质量指数，结果显示其明显高于普通条件下的Ａ３５６合金的质量指数。

The influence of the solidification conditions,heat treatment and Sr additions on an A356 alloy is investigated.The results show that the Sr additions affect not only the microstructure of the alloy,but also the precipitation behavior of the α Al solid solution.The effects of the cooling rate and Sr additions on the eutectic microstructures are still visible after the long solutionizing treatment.The quality index Q of the A356 type alloys(without Sr and with the optimal Sr content of 0 023%Sr) are compared before and after heat treatment with the Q values of the heat treated standard A356 alloy.The directionally solidified samples obtained higher Q values.