SBIR-STTR Award

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.

Metal matrix composites that may be used in deep space vehicles might be subjected to cryogenic temperatures near absolute zero in deep space. These composites develop large internal stresses due to the differential thermal expansion of the fibers and the matrix metal. It is necessary to know the ultimate breaking strength, the modulus of elasticity, the thermal expansion coefficient, and other mechanical characteristics of these materials for proper selection and design with them. This research will obtain the necessary test data for these parameters for various metal matrix composites including those that have been radiation damaged. Research will also be conducted to see the interfacial boundary between the fibers and the metal matrix using a scanning tunneling microscope.