Influence of Ru and Cr on the Heat-Treated Microstructure of Ni-Based Superalloys
The effects of ruthenium and chromium contents have been investigated on phase transformation temperatures and the morphology of γ’ precipitates as well as microstructural stability in high refractory Ni-base superalloys. The solidus and liquidus temperatures were determined by differential scanning calorimetry (DSC), suggesting that the addition of Cr resulted in a decrease in solidus/liquidus temperatures while the Ru addition (3.5 at.%) had the neutral effect. The morphology of γ’ precipitates in the heat-treated microstructure was changed under the influence of the Cr and Ru additions, suggesting that Ru and Cr contents affected the γ−γ’ lattice misfit through changes in the associated partitioning to the constituent phases. The microstructural instability has been investigated at 1000 oC. High levels of Cr addition (8 at.%) strongly promoted the formation of TCP phases, while Ru improved the microstructural stability to some extent.
Yafang Han et al.
W.B. Wang et al., "Influence of Ru and Cr on the Heat-Treated Microstructure of Ni-Based Superalloys", Materials Science Forum, Vols. 546-549, pp. 1207-1210, 2007