Computational Design of MoCr Superalloys for High Temperature Service

This Phase I project applies QuesTek’s unique computational materials design technology to the development of ductile, oxidation-resistant, and creep-resistant MoCr superalloys for use at 1300°C and above. Mo-Si-B or Nb-based systems developed for such demanding structural applications have encountered significant difficulties related to ductility and/or oxidation-resistance. QuesTek will pursue a radical new microstructural concept with the potential of achieving critical performance requirements simultaneously: novel multiphase Mo-Cr alloys composed of a ductile BCC matrix (for toughness) and aluminide phases for oxidation resistance and creep strength. Utilizing CALPHAD-based thermodynamics, and building on prior research at Northwestern University on refractory metal systems, the ductility and oxidation resistance of the Mo-Cr alloys will employ the following design strategies: a) Increasing the ductility of the BCC matrix phase by suitable alloying additions based on quantum-mechanical calculations of the generalized stacking fault energy, minimizing the matrix DBTT and b) Improving intrinsic oxidation resistance of the BCC matrix, using design methods for external protective oxide-scale formation. Phase I will design and validate proof-of-concept Mo-Cr alloys at sub-scale, and Phase II will develop, prototype, and characterize for subsequent implementation into DoD weapons platforms.