A study on the formation of crystalline phases during solidification and crystallisation in the bulk metallic glass of Zr₅₃Cu₂₁Al₁₀Ni₈Ti₈ composition

Abstract

The present paper considers the formation of crystalline phases during solidification and crystallisation of the Zr₅₃Cu₂₁Al₁₀Ni₈Ti₈ alloy. Solidification was carried out by a copper mould casting technique, which yielded a partially crystalline microstructure comprising a ‘big cube phase’ in a dendritic morphology and a bct Zr₂Ni phase. Detailed high-resolution microscopy was carried out to determine possible mechanisms for the formation of the crystalline phases. Based on microstructural examinations, it was established that the dendrites grew by the attachment of atomistic ledges. The bct Zr₂Ni phase, formed during solidification and crystallisation, showed various types of faults depending on the crystallite size, and its crystallography was examined in detail. It has been shown that the presence of these faults could be explained by anti-site occupancy in the bct lattice of the Zr₂Ni phase.

Keywords:

• bulk metallic glass
• big cube phase
• dendrites
• Zr₂Ni
• transmission electron microscopy (TEM)