Microstructures and properties of a novel γ′-strengthened multi-component CoNi-based wrought superalloy designed by CALPHAD method

Abstract

The γ′-strengthened Co-based superalloys have a lower γ′ solvus temperature and a higher γ′ volume fraction compared with Ni-based wrought superalloys, making this type of alloy more appropriate as a wrought superalloy for hot components of aero engines and industrial gas turbines, such as turbine disk. In order to accelerate the development and application of novel γ′-strengthened Co-based superalloys, CALPHAD method was employed to design a γ′-strengthened multi-component CoNi-based wrought superalloy with improved comprehensive performances on the basis of the Co–7Al–8W–4Ti–1Ta (at.%) quinary alloy. The preliminary evaluation of physical properties, microstructure, oxidation resistance, and mechanical properties of the designed alloy in as cast and as heat treated state shows that, in comparison with Ni-based wrought superalloys, the designed alloy which has a comparable density and a larger processing window, demonstrates better oxidation resistance and comparable mechanical properties. These results suggest that the CALPHAD method is helpful for the design and development of the γ′-strengthened multi-component CoNi-based superalloys, and the designed alloy has a potential for engineering application.