COATED REINFORCEMENT MATERIALS FOR IMPROVED STABILITY AND FABRICABILITY

THE PERFORMANCE AND EFFECTIVENESS OF SUPERSONIC OR HYPERSONIC TACTICAL MISSILES ARE DEPENDENT ON THE RELIABILITY OF FINS AND OTHER EXTERNAL STRUCTURAL COMPONENTS. CURRENT TITANIUM-BASED ALLOYS AND SUPERALLOYS USED IN AEROSPACE APPLICATIONS EITHER DO NOT HAVE ADEQUATE STRENGTH UNDER OPERATING CONDITIONS OF TEMPERATURE AND STRESS OR THEY ARE TOO HEAVY TO PROVIDE THE THRUST-TO-WEIGHT RATIO FOR THE PERFORMANCE DESIRED. AT THE DESIRED OPERATING SPEEDS OF MISSILES, THE EXTERNAL COMPONENTS, ESPECIALLY LEADING EDGES OF FINS, ATTAIN TEMPERATURES OVER 2000 DEG F. SINCE THE FINS PROVIDE FLIGHT STABILITY, IT IS ESSENTIAL THAT THEY ARE ABLE TO SUSTAIN FLIGHTINDUCED STRESSES AT THESE TEMPERATURES TO MAINTAIN THEIR STABILIZING FUNCTION. FURTHERMORE, SINCE THERE IS A CONTINUING DEMAND TO EXTEND RANGE AND MANEUVERABILITY, IT IS NECESSARY TO REDUCE MISSILE WEIGHT. SAMPLES OF BOTH LA(2)O(3-) COATED AND UNCOATED ALUMINA PARTICULATES WILL BE BLENDED WITH NIAL POWDER AND CONSOLIDATED INTO DISCONTINUOUSLY-REINFORCED COMPOSITES. THESE COMPOSITES WILL THEN BE THERMAL CYCLE TESTED. COMPOSITES WILL BE EVALUATED METALLOGRAPHICALLYTO ASSESS THE EXTENT OF MATRIX AND/OR INTERFACIAL CRACKING. IF AVAILABLE, WE WILL UTILIZE ATOMIZED NIAL POWDER (PRODUCED BY CRUCIBLE)AS THE MATRIX FOR THE INTERMETALLIC MATRIX COMPOSITES. SINGLE CRYSTALALUMINA WHISKERS ARE POTENTIALLY VERY ATTRACTIVE AS A REINFORCEMENT FOR MATRIX COMPOSITES, AND WE EXPECT TO COAT ALUMINA WHISKERS IN PHASE II.