Powder Processing of High Temperature Aluminide-Matrix Composites

Abstract

Aluminide intermetallic compounds are the basis for high performance, high temperature materials of the future. This presentation covers the use of reactive powder processing techniques for the formation of monolithic aluminide intermetallics and intermetallic-matrix composites. A notable development has been the fabrication of homogeneous, high density compacts from elemental powders by reactive sintering. A variant process involving simultaneous pressurization in a hot isostatic press, termed reactive hot isostatic pressing, is applicable to those compounds that prove difficult to consolidate by reactive sintering. This paper describes the effects of various processing factors on fabrication of dense aluminides with primary emphasis on Ni₃A1. Results on the fabrication of several other aluminide compounds will be discussed, including NiAl, TiAl, TaA1₃, and NbA1₃. Current research is on the use of these aluminides as the matrix for high temperature composites. A key concern is with processing effects on microstructure, selection of compatible ceramic reinforcing phases, and fiber alignment through injection molding.