MECHANICAL STRENGTH AND THERMAL-STABILITY OF TI-BASED AMORPHOUS-ALLOYS WITH LARGE GLASS-FORMING ABILITY

Ti-based alloy powders produced by the high pressure gas atomization technique were found to consist of an amorphous single phase in the particle size range below 32 mum for Ti50Zr10Cu40, and below 25 mum for Ti50Zr10Ni20Cu20, though the cooling rate of their molten alloys for gas atomization is considerably lower than that for melt spinning. In addition, the Ti-Zr-Cu amorphous powders exhibit a rather wide supercooled liquid region before crystallization. This is believed to be the first evidence for the appearance of the supercooled liquid region for atomized Ti-based amorphous powders. The significant increase in the glass-forming ability and the wide temperature range of the supercooled liquid region for the Ti-Zr-Cu ternary alloys are presumably due to the simultaneous satisfaction of the two criteria of the significantly different atomic size ratios among the constituent elements and the difficulty of long-range redistribution of the constituent elements for the growth of crystalline phases.