Production of Al-Zr master alloy starting from ZrO2

A process involving in-situ reduction of zirconium oxide with excess alumin um in the presence of cryolite flux has been developed for the preparation of a Al-Zr master alloy. The findings of this process are reproduced on dou bling the batch size, and pilot scale results indicated viability of the pr ocess for commercial scale exploitation. It has been found possible to prod uce Al-5%Zr alloy in batches of 20 kg with over 92% yield on holding the ch arge for 1 h in the temperature range of 1100-1200 degrees C. The addition of the master alloy to pure aluminum to the extent of 0.3%Zr in Al, effecti vely reduced the grain size from 1100 to 163 mu m and correspondingly impro ved the ultimate tensile strength (UTS) of Al. The present process is found to have an edge over the conventional process of direct alloying. (C) 1999 Elsevier Science S.A. All rights reserved.