Heat Treatment of Al-Cu Alloys in the Semisolid State

摘要

The microstructural changes in two hypoeutectic Al-8.4Cu and Al-31Cu alloys have been examined after semisolid heat (SSH) treatment. This treatment for Al-8.4Cu alloy was done at 853°K for 1, 2, and 4 hr. whereas for Al-31Cu alloy, it was done at 853°K for 1 hr. and at 863°K for 30 min. In addition, the ageing characteristics of Al-8.4Cu alloy were studied with or without SSH treatment. The microstructures of Al-8 4Cu alloy exhibit gradual spheroidisation of the eutectic constituents and lead to a composite structure of α-Al with dispersed θ(CuAl{sub}2). The initial cast structure of Al-31Cu alloy, on the other hand, leads to a two phase mixture of α and θ phases when subjected to SSH treatment at 863K for 30 min. The ageing behaviour of Al-8.4Cu alloy with or without SSH treatment is found to be significantly different.