MECHANICAL AND INTERFACIAL CHARACTERIZATION OF FE3AL AND FE3AL-AL2O3 INTERMETALLIC COMPOSITE MADE BY MECHANICAL SMEARING AND HOT ISOSTATIC PRESSING

Close-to-theoretical-density compacts of Fe3Al intermetallic and its c omposite with 4vol% Al2O3 were made by mechanical smearing of powders, followed by Hot Isostatic Pressing. Mechanical characterisation of th e compacts were carried out, predominantly, by ultramicro-indentation technique. The materials exhibited very high mechanical properties, an d in particular, the composite compact appeared to possess 50% more st rength than, and the same modulus of elasticity as, ultra high strengt h steels. The Al2O3 in the composite preferentially occupied the grain boundary positions giving rise to a grain boundary hardness of 9 GPa. The hardness decreased to 6 GPa in the interior, and a functionally g raded zone, 0.6-1.0 mu m in thickness was observed. Electron probe mic roanalysis profiles showed good correlation with the results of the me chanical study. (C) 1997 Elsevier Science Limited.