DISCONTINUOUSLY REINFORCED MAGNESIUM FOR MISSILE COMPONENTS

PRESENT AND FUTURE GENERATION NAVY MISSILES REQUIRE METAL MATRIX COMPOSITE MATERIALS WITH PROPERTIES TAILORED FOR USE AS HEAT SINKS, MIRRORS, OR STABLE PLATFORMS. A NEW PARTICULATE REINFORCED MAGNESIUM ALLOY MATERIAL OFFERING AN OUTSTANDING COMBINATION OF LOW DENSITY, LOW COEFFICIENT OF THERMAL EXPANSION (CTE), HIGH THERMAL CONDUCTIVITY WITH ISOTROPIC PROPERTIES IS PROPOSED. THE MATERIAL CAN BE PROCESSED IN MUCH THE SAME MANNER AS EXISTING PARTICULATE REINFORCED MAGNESIUM COMPOSITE MATERIALS. AT A NOMINAL REINFORCEMENT LOADING OF 20% BY VOLUME, A THERMAL CONDUCTIVITY OF 190 W/M-K IS PREDICTED, FAR SUPERIOR TO THE 110 W/M-K MEASURED FOR 20% VOLUME LOADED SIC WHISKER REINFORCED MAGNESIUM ALLOY. AT THE SAME LOADING A CTE OF 5.8 X 10(-6) M/M/K IS PREDICTED FOR THE PROPOSED MATERIAL, COMPARED WITH 12.2 X 10(-6) FOR THE EXISTING SIC REINFORCED MAGNESIUM ALLOY. THE EQUIAXED NATURE OF THE REINFORCEMENT LEADS TO THESE PROPERTIES BEING ISOTROPIC. THE PROPOSED PROGRAM IS CENTERED ON THE FABRICATION OF THIS NEW MATERIAL AND SUBSEQUENT TEST OF IT'S PROPERTIES TO DEMONSTRATE THAT THEY ARE AS PREDICTED, AND ISOTROPIC IN NATURE. TESTS WILL INCLUDE METALLOGRAPHY, SCANNING ELECTRON MICROSCOPY (SEM), DENSITY, COEFFICIENT OF THERMAL EXPANSION, AND THERMAL CONDUCTIVITY.