RAPID SOLIDIFICATION OF INTERMETALLIC COMPOUNDS

This review surveys recent studies of rapid solidification at alloy compositions where the equilibrium phase is an intermetallic compound (or mixture of intermetallic compounds). Glass forming intermetallic compositions are considered and criteria for 'easy' glass formation are discussed. The limited data on synthesis of intermetallics from amorphous precursors are reviewed. This is a promising route to refine the microstructure of intermetallics with the potential for improved mechanical properties. Rapid solidification of nickel base aluminides results in a refined microstructure (grain size and/or antiphase domain size) which can influence mechanical properties. The equilibrium crystal structure is maintained, however. Certain rapidly solidified Fe-Al-C base alloys can form a metastable fcc or L12 structure (a point of continuing controversy) with good strength and ductility. The titanium base aluminides exhibit a tendency for formation of metastable structures on rapid quenching. The potential for improving the ductility of these compounds has made rapid solidification of Ti3Al and TiAl the subject of much recent activity.