ADVANCED INTERMETALLIC ALLOYS - BEYOND GAMMA-TITANIUM ALUMINIDES

Recent studies have shown that Nb-base refractory intermetallic materi als may be viable for service at temperatures that compete with the ni ckel-based superalloys in structural applications. While advanced inte rmetallics in monolithic form have limited prospects for providing the required balance of properties for use at high operating temperatures , two-phase or multiphase intermetallic systems composed of a ductile, Nb-base refractory phase in equilibrium with one or more silicide int ermetallics show promise for further development as structural materia ls. Exploratory efforts on these systems have indicated that damage to lerance, creep resistance and oxidation tolerance may be obtained and controlled simultaneously. In turn, these findings have led to alloy d evelopment strategies and approaches which are currently under investi gation and are expected to lead to focused research on a small set of alloys. This manuscript presents an overview of recent results on sele cted Nb-base intermetallic systems with particular emphasis on phase e quilibria and mechanical behavior. (C) 1997 Elsevier Science S.A.