Quasicrystalline phases in conventionally cast Fe-containing Al-Cu-Mn alloys and its evolution during the annealing at 530°C

Abstract

This study investigates the stabilization of icosahedral quasicrystal (I-phase) in conventionally cast Fe-containing Al-Cu-Mn alloys and its decomposition to decagonal quasicrystal (D-phase) by annealing at 530°C for different time durations (16–48 h). It is observed that in the as-cast Al-Cu-Mn-Fe alloy with a high content of Cu and Mn, I-phase is present in the form of a composite structure with a chemical constituent of Al65Cu20(Mn,Fe)15. Grain boundaries and triple junctions are partially or pseudopartically wetted by θ-Al2Cu phase and completely wetted by T-Al20Cu2Mn3 phase, respectively. Upon annealing at 530°C for different time durations, I-phase, by consuming θ-Al2Cu phase in the grain boundary, transforms into D-phase and T-Al20Cu2Mn3 phase without having Fe. Hence, Fe plays a key role in the stabilization of I-phase in the conventionally cast Al-Cu-Mn alloys but does not take part in its transformation to D-phase and T-Al20Cu2Mn3 phase.