Characterisation of evolution of microstructure during processing of Al–Li–Mg–Cu–Zr cast alloys

Abstract

The as cast microstructures of Al–2·5Li–2Mg–0·14Zr alloys containing 0, 0·1, 0·3, or 0·5%Cu are characterised and the phases present are identified. A combination of light microscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction techniques was used. The changes accompanying subsequent treatments, i.e. homogenisation, hot deformation, solution treatment, and aging, have also been investigated. The Al₆CuLi₃ (T₂) phase is found to be present in the form of tiny particles in a non-equilibrium eutectic in the as cast Cu containing alloys. This is responsible for the partial melting of these alloys at ∼545°C.

MST/1825