Disperse structure forming in rapidly quenched Al-Hf alloy

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