Composition effects on mechanical properties of HfC-strengthened molybdenum alloys

The mechanical properties of swaged rod thermomechanically processed from arc-melted Mo--2Re--Hf--C alloys containing as much as 0.9 mol percent HfC have been evaluated. The low temperature ductilities of these alloys were not influenced by the amount of HfC present but by the amount of Hf in excess of stoichiometry. Maximum ductility occurred at 0.2 to 0.3 at. percent excess Hf. At 0.3 to 0.5 mol percent HfC, alloy strength varied directly with the Mo content of extracted carbide particles, both decreasing as the amount of excess Hf increased. Additions of 2 at. percent Re had little effect on strength or ductility. Tensile and creep strengths of Mo--2Re--0.7Hf--0.5C alloy equaled or exceeded those of other high strength Mo alloys