Investigation on Formation Mechanism of Cu/Cr-Al2O3 Nanocomposite

In this research, formation mechanism of a Cu/10 wt.% Cr-10 wt.% Al2O3 nanocomposite via mechanical alloying and subsequent heat treatment has been investigated. It was found that during milling process, Cu (Al) solid solution and Cu9Al4 phase were formed as intermediate products. Further heat treatment carried out under argon atmosphere at 900°C for 8 hours resulted in completion of Cr2O3 reduction by Al. The mechanism of in-situ formation of Al2O3 reinforcement in the copper matrix was also discussed as a two stages process. The SEM and TEM results confirmed the proposed mechanism and showed that the Cr dispersoids surrounded by Al2O3, in the nanometric scale. Also, the Cu matrix with mean crystallite size of 30 nm was stable at high temperature.