BEHAVIOR OF METAL MATRIX COMPOSITES AT CRYOGENIC TEMPERATURES

METAL MATRIX COMPOSITES THAT MAY BE USED IN DEEP SPACE VEHICLES MIGHT HAVE SEVERE INTERNAL STRESSES DUE TO THE THERMAL EXPANSION DIFFERENCES BETWEEN THE MATRIX AND THE FIBERS. SINCE THE TEMPERATURES EXPERIENCED WITH THESE VEHICLES MAY BE AS LOW AS A FEW DEGREES ABOVE ABSOLUTE ZERO, IT IS NECESSARY TO KNOW THE THERMAL MECHANICAL BEHAVIOR OF METAL MATRIX COMPOSITES TO BE USED AS STRUCTURAL MATERIALS. THE PURPOSE OF THIS PROPOSED EFFORT IS TO BUILD A CRYOSTAT CAPABLE OF MECHANICALLY TESTING THESE MATERIALS FROM ROOM TEMPERATURE DOWN TO LIQUID HELIUM TEMPERATURES, APPROXIMATELY 4 DEGREES KELVIN. BOTH COMPRESSION AND TENSILE TESTS WOULD BE DONE. A PHASE II EFFORT WOULD BE DESIRABLE FOR DEVELOPING A DATA BASE OF MECHANICAL PROPERTIES OF MATERIALS AT CRYOGENIC TEMPERATURES.