Design of high-strength refractory complex solid-solution alloys

Prashant Singh, Ames Laboratory
Aayush Sharma, Iowa State University
A. V. Smimov, Ames Laboratory
Mouhamad Diallo, Iowa State University
Pratik K. Ray, Iowa State University and Ames Laboratory
Ganesh Balasubramanian, Lehigh University
Duane D. Johnson, Iowa State University and Ames Laboratory

Abstract

Nickel-based superalloys and near-equiatomic high-entropy alloys containing molybdenum are known for higher temperature strength and corrosion resistance. Yet, complex solid-solution alloys offer a huge design space to tune for optimal properties at slightly reduced entropy. For refractory Mo-W-Ta-Ti-Zr, we showcase KKR electronic structure methods via the coherent-potential approximation to identify alloys over five-dimensional design space with improved mechanical properties and necessary global (formation enthalpy) and local (short-range order) stability. Deformation is modeled with classical molecular dynamic simulations, validated from our first-principle data. We predict complex solid-solution alloys of improved stability with greatly enhanced modulus of elasticity (3× at 300 K) over near-equiatomic cases, as validated experimentally, and with higher moduli above 500 K over commercial alloys (2.3× at 2000 K). We also show that optimal complex solid-solution alloys are not described well by classical potentials due to critical electronic effects.