Design of high-strength refractory complex solid-solution alloys

P Singh and A Sharma and AV Smirnov and MS Diallo and PK Ray and G Balasubramanian and DD Johnson, NPJ COMPUTATIONAL MATERIALS, 4, 16 (2018).

DOI: 10.1038/s41524-018-0072-0

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 (3x at 300 K) over near-equiatomic cases, as validated experimentally, and with higher moduli above 500 K over commercial alloys (2.3x at 2000 K). We also show that optimal complex solid-solution alloys are not described well by classical potentials due to critical electronic effects.

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