Accelerated discovery of oxidation resistant CoNi-base γ/γ’ alloys with high L12 solvus and low density

Abstract

A systematic and accelerated methodology for alloy design is demonstrated by combining combinatorial synthesis, high-throughput oxide scale characterization, computational density functional theory, and CALPHAD database calculations. By applying this strategy to the senary Co-Ni-W-Al-Cr-Ta material system, a novel γ/γ’ alloy exhibiting a superior combination of properties has been identified. Properties include a γ’ solvus near 1200 °C, continuous α-Al2O3 scale formation after 1 h in air at 1100 °C, and comparable density to 2nd-generation commercial Ni-base superalloys. This novel alloy SB-CoNi-10 has a nominal composition of 39.8Co – 36.5Ni – 13.2Al – 1.0W – 6.0Cr – 3.5Ta at.%, and its properties are compared with other recently studied Co-, CoNi-, and Ni-base γ/γ’ alloys. Keywords: Cobalt-base Superalloys, Oxidation, Combinatorial synthesis, Superalloys, Alloy design