The Effect of the Presence of 2 wt% Hafnium in T‐111

Tantalum alloys have been used by the U.S. Department of Energy as structural alloys for space nuclear power systems such as Radioisotopic Thermoelectric Generators (RTG) since the 1960s. Tantalum alloys are attractive for high temperature structural applications due to their high melting point, excellent formability, good thermal conductivity, good ductility (even at low temperatures), corrosion resistance, and weldability. A number of tantalum alloys have been developed over the years to increase high‐temperature strength (Ta‐10%W), and reduce creep strain (T‐111). These tantalum alloys have demonstrated sufficient high‐temperature toughness to survive prolonged exposure to the RTG’s working environment. Due to the commercial unavailability of the tantalum alloy T‐111, Ta‐10%W is a possible candidate replacement material because of its high melting point (3037 °C), high elastic modulus (207 GPa), high yield, ultimate tensile strengths at both ambient and elevated temperatures, excellent ductility, and e...