Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7970528 | Materials Characterization | 2015 | 8 Pages |
Abstract
The microstructure of a new Ni-base oxide dispersion strengthened superalloy powder was studied for high temperature gas turbine applications after the mechanical alloying process. In this study, an atomized powder with a composition similar to the CMSX-10 superalloy was mechanically alloyed with yttria and Hf powders. The mechanically alloyed powder included only the supersaturated solid solution γ phase without γⲠand yttria provided by severe plastic deformation, while after the 3-step aging, the γⲠphase was precipitated due to the partitioning of Al and Ta to the γⲠand Co, Cr, Re, W, and Mo to the γ phase. Mechanical alloying modified the morphology of γⲠto the new coherent γ-γⲠnanoscale lamellar structure to minimize the elastic strain energy of the precipitation, which yielded a low lattice misfit of 0.16% at high temperature. The γⲠlamellae aligned preferentially along the elastically soft [100] direction. Also, the precipitated oxide particles were refined in the γ phase by adding Hf from large incoherent YAlO3 to fine semi-coherent Y2Hf2O7 oxide particles with the average size of 7 nm and low interparticle spacing of 76 nm.
Keywords
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Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
S.M. Seyyed Aghamiri, H.R. Shahverdi, S. Ukai, N. Oono, K. Taya, S. Miura, S. Hayashi, T. Okuda,