MECHANICAL ACTIVATION OF THE FORMATION OF AN ALUMINA-TITANIUM TRIALUMINIDE COMPOSITE

The fabrication of a powder composed of alumina and titanium trialumin ide TiAl3 from TiO2 and aluminium powder is reported in this paper. Th e powders were ball-milled together under vacuum for 100h in a laborat ory scale mill with no reaction evident directly after milling. Differ ential thermal analysis showed that the milled powder underwent an exo thermic reaction below the melting point of aluminium. An unmilled pow der underwent a slow reaction until an exothermic reaction occurred at 1000 degrees C. The milled powder showed complete reaction to Al2O3 a nd TiAl3 after heating to 600 degrees C whereas the unmilled powder re action was incomplete after 1 h at 1200 degrees C. Analysis of the ene rgetics of the reactions suggested that the milled powder would underg o self-propagation, whereas the unmilled powder would not. (C) 1998 Pu blished by Elsevier Science Limited. All rights reserved.