Phase transformations in a Cu–25at.%Al–7.5at.%Mn alloy

The as-quenched microstructure of the Cu–25at.%Al–7.5at.%Mn alloy was D03 phase containing extremely fine L–J precipitates (the L–J phase is a new type of precipitate, which was firstly observed and identified by Liu and Jeng (designated L–J phase) in a Cu2.2Mn0.8Al alloy.). When the as-quenched alloy was aged at temperatures ranging from 500 °C to 700 °C, the phase transition sequence was found to be (γ-brass + L–J + D03) → (γ-brass + L–J + B2) → β. This result is different from that reported by previous workers in Cu–25at.%Al–(0–8)at.%Mn alloys.