Disperse structure forming in rapidly quenched Al-Hf alloy

Abstract

Thr structure of the Al-1.4 wt.% Hf alloy was investigated depending on overheating initial melt above liquidus and cooling rate at solidification. It was shown that varying melt overheating, one can control cost structure formation. The most disperse structure forms at the temperature slightly below 1470 K. According to results of viscosity measurements, the last temperature corresponds to irreversible homogenization of the melt. It was discovered that overheating the melt above its homogenization tempeature results in grain coarsening, appearance of spherulite-like and dendrite forms of solid phase growth and formation of metastable alpha -solid solution abnormally over-saturated by hafnium. (C) 2001 Elsevier Science B.V. All rights reserved.