C-Mo And C-Zr Alloys For Space Power Systems

The C-Mo and C-Zr alloy systems were investigated as possible candidates for high temperature applications in extraterrestrial power systems. Alloys containing 0 to 6 weight percent carbon were produced using induction melting techniques. The Zr-C alloys produced were found to be composed of alpha-Zr and gamma (ZrC), while the Mo-C alloys were composed of theta (Mo2C) and the eutectic mixture of Mo plus theta. The volume fraction of carbide increased as the carbon content was increased. Half of all alloys produced were annealed. The Mo-C alloys were heat treated in a vacuum furnace at 1370°C / 1 hr. / FC while the Zr-C alloys were annealed at 1000°C / 1 hr. / FC> Room temperature compression tests were performed on both the as-cast and annealed material. The results of these tests are described as a function of the volume fraction of the primary carbide phase present. The indicated a decrease in strength and a decrease in ductility as the volume fraction of carbide increased. Annealing was found to improve the properties over those of the as-cast materials. Microhardness of ZrC increased but all other phases seemed to be relatively independent of the carbide or C-content.