共晶硅的变质

Modification of Eutectic Silicon in Al-Si Cast Alloys

文章综述了共晶硅的变质机理及常用变质元素的特性。最为人们接受的硅的变质机理是Lu和Hellawell提出的杂质诱发孪晶假说。Na变质能力强,但存在变质衰退快及过变质等问题。Sr具有较好的变质能力,同时变质有效期长,没有明显的过变质问题,其变质孕育期的长短主要与合金中的磷的含量有关。Sb变质具有长效性,重熔后仍然具有变质的能力,但变质效果较差,其变质机理与Na和Sr不同。

The modification mechanism of the eutectic Si in Al-Si cast alloy and the characters of the modifiers commonly used were reviewed in this paper. The well accepted hypothesis on modification of the eutectic silicon in Al-Si cast alloy is the 'impurity induced twinning' proposed by Lu and Hellawell. Na is the most effective modifier. The problem with Na is the over-modification and very short effective period of modification. Sr is an effective modifier and shows a longer effective modification period without over-modification problem. Its modification incubation period is related to the concentration of P. Sb shows a very long effective modification period and is with the modification ability even after remelting. The modification mechanism of Sb differs from that of Na and Sr.