Improving Intermediate Temperature Plasticity of Co–Al–W–Base Superalloy: Based on Optimizing MC Carbides

Abstract

The brittleness of the new Co–Al–W–base superalloys is said to be a fatal weakness for their application in the intermediate temperature range, especially for polycrystal Co–Al–W–base superalloys. MC carbide controlling is used to improve the intermediate temperature plasticity of the Co–Al–W–base superalloy in the present study. Both microstructure characterization and interrupted tensile tests were performed to investigate the mechanism of improving the plasticity of the superalloy by MC carbides at an intermediate temperature of 800 °C. The results show that the plasticity of the superalloy is mainly dependent on MC carbides. MC carbide breakers appear after yielding, which closely depends on the morphology and size of MC carbides. Based on the experimental and calculation results, it is found that the intermediate temperature plasticity of the superalloy can be guaranteed by controlling the critical mean size of MC carbides, and the desired mean size of MC carbides should be less than 47 μm.

Keywords

• Co–Al–W–base superalloy
• plasticity
• MC carbide
• interrupted tensile test