Enhancing strength and γ’-coarsening resistance through micro-alloying additions to an oxidation resistant Al-Co-Cr-Fe-Ni-Ti compositionally complex alloy

Abstract

The effect of alloying additions of Mo and Ta (0.4 at% each) on the microstructure, mechanical properties, oxidation resistance and coarsening resistance of the L12-strengthened (γ’) Al-rich Ni51Co18Fe5Cr10Al12Ti4 alloy was determined. The micro-alloyed composition exhibited improved yield strength (from room temperature to 1000 °C) and coarsening resistance (enhanced by 33 % at 800 °C) compared to the base Ni51Co18Fe5Cr10Al12Ti4 alloy. The present Al-rich alloy compositions (both the micro-alloyed and reference compositions) exhibited superior oxidation resistance (800–1000 °C) compared to a Ti-rich Ni51Co18Fe5Cr10Al8Ti8 alloy (with similar precipitate volume fraction and (Al+Ti)-content) and commercial Inconel 718. The present work highlights the promise of Al-rich γ’-strengthened Al-Co-Cr-Fe-Ni-Ti alloys as candidates for high-performance, high-temperature structural materials, characterised by an attractive blend of strength, resistance to coarsening, and resilience against oxidation.

Keywords

• High entropy superalloy
• Precipitation strengthening
• Mechanical properties
• High-temperature strength
• Coarsening resistance
• Oxidation resistance