Microstructural characterization of a new mechanically alloyed Ni-base ODS superalloy powder

Journal Article · Sun Feb 15 04:00:00 EST 2015 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2014.12.008· OSTI ID:22476039

Seyyed Aghamiri, S. M. ^[1]; Ukai, S.; Oono, N.; Taya, K.; Miura, S.; Hayashi, S. ^[2]; Okuda, T. ^[3]

---

1. Department of Materials Engineering, Tarbiat Modares University, Tehran 14115-143 (Iran, Islamic Republic of)
2. Material Science and Engineering, Faculty of Engineering, Hokkaido University, Sapporo 060-8626 (Japan)
3. Kobelco Research Institute Ltd., Kobe 651-2271 (Japan)

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 γ′ and yttria provided by severe plastic deformation, while after the 3-step aging, the γ′ phase was precipitated due to the partitioning of Al and Ta to the γ′ and Co, Cr, Re, W, and Mo to the γ phase. Mechanical alloying modified the morphology of γ′ to the new coherent γ–γ′ nanoscale lamellar structure to minimize the elastic strain energy of the precipitation, which yielded a low lattice misfit of 0.16% at high temperature. The γ′ lamellae 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 YAlO{sub 3} to fine semi-coherent Y{sub 2}Hf{sub 2}O{sub 7} oxide particles with the average size of 7 nm and low interparticle spacing of 76 nm. - Highlights: • A new Ni-base ODS superalloy powder was produced by mechanical alloying. • The nanoscale γ–γ′ lamellar structure was precipitated after the aging treatment. • Fine semi-coherent Y{sub 2}Hf{sub 2}O{sub 7} oxide particles were precipitated by addition of Hf.

• OSTI ID: 22476039
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 100; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINATES
GAS TURBINES
HAFNIUM
HEAT RESISTING ALLOYS
HYDROFLUORIC ACID
LAMELLAE
MICROSTRUCTURE
NANOSTRUCTURES
NICKEL ALLOYS
PLASTICITY
POWDERS
PRECIPITATION
SOLID SOLUTIONS
STRAINS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES