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 t echnique were found to consist of an amorphous single phase in the par ticle size range below 32 mum for Ti50Zr10Cu40, and below 25 mum for T i50Zr10Ni20Cu20, though the cooling rate of their molten alloys for ga s atomization is considerably lower than that for melt spinning. In ad dition, the Ti-Zr-Cu amorphous powders exhibit a rather wide supercool ed liquid region before crystallization. This is believed to be the fi rst evidence for the appearance of the supercooled liquid region for a tomized Ti-based amorphous powders. The significant increase in the gl ass-forming ability and the wide temperature range of the supercooled liquid region for the Ti-Zr-Cu ternary alloys are presumably due to th e simultaneous satisfaction of the two criteria of the significantly d ifferent atomic size ratios among the constituent elements and the dif ficulty of long-range redistribution of the constituent elements for t he growth of crystalline phases.