Decagonal quasicrystalline phase in as-cast and mechanically alloyed Al-Cu-Cr alloys

摘要

Microstructure and phase composition of three Al-rich as-cast alloys of Al-Cu-Cr system were investi gated by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The decagonal quasi-crystalline phase is contained in all alloys under study and has grains with faceted shape, its composition lies in the range of 71-73 at.% Al, ll-12at.% Cu and 15-18at.% Cr. The heating in calorimeter of the mechanically alloyed Al_(73)Cu_(11)Cr_(16) powder up to 600 °C leads to the formation of the pure decagonal phase. Total thermal effect in the temperature range 250-600 °C corresponding to the quasicrystalline phase formation is about 15 kj/mol.