Mechanical and interfacial characterisation of Fe3Al and Fe3Al-Al2o3 intermetallic composite made by mechanical smearing and hot isostatic pressing

Abstract

Close-to-theoretical-density compacts of Fe3Al intermetallic and its composite with 4 vol% A12O3 were made by mechanical smearing of powders, followed by Hot Isostatic Pressing. Mechanical characterisation of the compacts were carried out, predominantly, by ultramicro-indentation technique. The materials exhibited very high mechanical properties, and in particular, the composite compact appeared to possess 50% more strength than, and the same modulus of elasticity as, ultra high strength steels. The A12O3 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 graded zone, 0.6-1.0 μm in thickness was observed. Electron probe microanalysis profiles showed good correlation with the results of the mechanical study.