Coarsening Behavior of γ'Precipitates and Compression Performance of Novel Co-Ni-Al-W Superalloy
The coarsening behavior of γ'precipitate phase at different temperatures and the compressive performance of novel Co-Ni-Al-W superalloy were investigated.Experiment results show that the evolution of the mean radius and volume fraction of the γ'phase obeys the classical Lifshitz-Slyozov-Wagner model.The coarsening rate of the γ'phase exhibits a significant dependence on the aging temperature,which increases from 1.30×10-27 m3/s at 800 ℃ to 9.56× 10-27 m3/s at 900 ℃.The activation energy of γ'phase is mainly influenced by the W diffusion in the y matrix,presenting as 210 kJ/mol.The prepared Co-Ni-Al-W alloy possesses superb comprehensive properties,particularly the good combination of high y'solvus temperature(1221 ℃)and low density(8.7 g/cm3).Besides,the compressive yield strength of the Co-Ni-Al-W alloy at ambient and high temperatures are higher than that of otherγ'-strengthened Co-based superalloys.The compressive yield strength of the Co-Ni-Al-W alloy at 850 ℃ is as high as 774 MPa.
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