Crystallization behaviour of Al-based metallic glasses below and above the glass-transition temperature

The present paper aims to report an effect of a supercooled liquid region on crystallization behaviour of the Al85Y8-xNdxNi5Co2 metallic glasses produced by rapid solidification of the melt. The paper describes the crystallization process at different regimes of heat treatment. It is found that crystallization behaviour of the above-mentioned Al-based metallic glasses above the glass-transition temperature and below it follows different transformation mechanisms. Formation of the primary nanoscale alpha-Al particles was observed during continuous heating or after isothermal annealing above the glass-transition temperature. During isothermal annealing below the glass-transition temperature an unknown metastable phase is formed conjointly with alpha-Al. The metastable phase formed in the Nd-free alloy varies from that in the Nd-bearing alloys. Al85Nd8Ni5CO2 amorphous alloy exhibiting no glass transition crystallizes equally during isothermal calorimetry at different temperatures and during continuous heating. (C) 2002 Elsevier Science B.V. All rights reserved.