MOLYBDENUM SILICIDE BASED HIGH TEMPERATURE MATERIALS WITH ENHANCED DUCTILITY AND TOUGHNESS

MOLYBDENUM-SILICIDE BASED MONOLITHIC AND COMPOSITE MATERIALSHAVE POTENTIAL AIRCRAFT APPLICATIONS IN THE TEMPERATURE RANGE 1000-1600 DEGREES CENTIGRADE. MOLYBDENUM-SILICIDE BASED INTERMETALLICS HAVE PROVEN TO BE RATHER FORMIDABLE MATERIALS TO PROCESS BECAUSE OF ITS EXTREME BRITTLENESS. INORDER TO SUCCESSFULLY PROCESS AND FABRICATE COMPONENTS BASEDON MOLYBDENUM-SILICIDE, IT IS NECESSARY TO ENHANCE ITS LOW TEMPERATURE, DUCTILITY AND TOUGHNESS. THIS RESEARCH FOCUSES ON PREPARATION OF FINE GRAINED MOLYBDENUM-SILICIDE, VIA ADVANCED RAPID SOLIDIFICATION AND POWDER METALLURGICAL PROCESSING TO IMPROVE ITS LOW TEMPERATURE DUCTILITY AND TOUGHNESS. THE FINE GRAIN SIZE WILL REDUCE THE SLIP LENGTH, THEREFORE, LOWER THE STRESS CONCENTRATION AT THE GRAIN BOUNDARIES AND THUS ENHANCE DUCTILITY. PHASE I RESEARCH WILL ALSO INVESTIGATE THE EFFECT OF TIB2 AND HFC DISPERSOIDS ON GRAIN REFINEMENT. IT IS EXPECTED THAT THESE STABLE DISPERSOIDS WILL RETAIN THE FINE MICROSTRUCTURE AS WELL AS AID IN DISPERSING PLANAR SLIPSO THAT FRACTURE WILL OCCUR THROUGH THE FORMATION OF VOIDS AROUND THESE INCOHERENT PARTICLES, ESPECIALLY AT HIGHER TEMPERATURES. PHASE II RESEARCH WILL INVESTIGATE IN MORE DETAIL THE DISPERSOID/GRAIN BOUNDARY AND DISPERSOID/DISLOCATION INTERACTIONS TO DEFINE THE PROCESSING-MICROSTRUCTURE-MECHANICAL PROPERTY RELATIONSHIPS SO THAT OPTIMUM MECHANICAL PROPERTIES WILL BE ATTAINED AT BOTH ROOM AND ELEVATED TEMPERATURES.