Glass-liquid transition in a less-stable metallic glass

A stable metallic glass, SMG, is often viewed as an amorphous alloy exhibiting a reversible glass ↔ liquid transition. Here we show experimentally that even in a less-stable metallic glass, LMG, which is prepared only by rapid melt quenching and promptly crystallized without glass transition at the ordinary heating rate, sufficiently rapid heating exposes the glass→liquid transition by suppressing crystallization. The experimental glass transition Tg and crystallization Tx temperatures were plotted as a function of heating rate β, for Pd42.5 Ni7.5 Cu30 P20 of SMG and for Zr70 Ni30 of LMG. Two extrapolated curves, Tg -log β and Tx -log β, intersect at a quite small β, e.g., ∼ 10-4°C/min, for SMG, whereas their intersection occurs at a large β, e.g., ∼10°C/min, for LMG. Such a large β that is comparable to conventional heating rates makes it difficult to observe the reversible glass transition in LMG, and reflects low thermal stability of the glassy state.