FINE GRAINED NICKEL-ALUMINIDE ALLOY WITH IMPROVED TOUGHNESS MADE VIA RAPID SOLIDIFICATION TECHNOLOGY

INTERMETALLICS REPRESENT A LARGE CLASS OF MATERIALS WHOSE POTENTIAL FOR USE IN HIGH TEMPERATURE ENVIRONMENTS HAS BASICALLY BEEN IGNORED IN FAVOR OF CERAMICS. WHILE MANY CANDIDATE INTERMETALLICS ARE BRITTLE, DIRECTIONALLY BONDED COMPOUNDS; A FEW, SUCH AS THE EQUIATOMIC ALUMINIDES OF IRON,NICKEL, AND COBALT DO POSSESS METALLIC-LIKE BEHAVIOR. THESEALUMINUM CONTAINING INTERMETALLIC HAVE B2 CUBIC CRYSTAL STRUCTURES, HAVE LARGE SOLUBILITIES FOR THIRD ELEMENT ALLOYING ADDITIONS, ARE CAPABLE OF BOTH LOW AND HIGH TEMPERATURE PLASTIC FLOW, AND HAVE VERY HIGH MELTING TEMPERATURES (1900K) EXCEPT FOR FEA1. WE PROPOSE A RESEARCH PROJECT TO STUDY FINE GRAINED NICKEL ALUMINIDE (NIAL) ALLOYS CONTAINING A DISPERSION OF ULTRAFINE TITANIUM DIBORIDE PARTICLES TO BE PREPARED USING THE TECHNIQUES OF RAPID SOLIDIFICATION AND THERMOMECHANICAL PROCESSING. THE PRIMARY FOCUS WILL BE ON CHARACTERIZATION OF BOTH LOW AND HIGH TEMPERATURE PLASTIC FLOW AND DEVELOPMENT OF BASE LINE MECHANICAL PROPERTIES AS WELL AS ANUNDERSTANDING OF THE FACTORS WHICH AFFECT/CONTROL THE STRENGTH AND DUCTILITY. ANOTHER MAJOR OBJECTIVE IS TO UNDERSTAND THE ROLE OF GRAIN REFINEMENT AND TITANIUM DIBORIDE DISPERSIONS ON THE MECHANICAL BEHAVIOR OF THE NICKEL ALUMINIDE.