Dispersoids and γ′ precipitates in an ultrafine grained René 88DT – 5vol.%Y2O3 alloy with outstanding thermal stability
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)
Highlights: • Dispersoids and precipitates in UFG René 88DT was systematically studied. • TiN and Y4Al2O9 particles are thermally stable in UFG René 88DT. • High thermal stability of the UFG structure was achieved by dispersoids formation. - Abstract: We report on an ultrafine-grained (UFG) René 88DT-5vol.%Y{sub 2}O{sub 3} alloy with a high thermal stability fabricated through high energy mechanical milling and thermomechanical powder consolidation. The as-extruded sample consists of an ultrafine grained γ matrix with an average size of 122 nm with Y{sub 4}Al{sub 2}O{sub 9} nanoparticles (average size: 12.6 nm) and TiN particles (size about 150 nm) being dispersed in the matrix. The UFG microstructure of the alloy showed an outstanding thermal stability with the average grain size only increasing slightly from 122 to 145 nm after holding at 1120 °C (0.85T{sub m}, where T{sub m} is the solidus temperature of the alloy in Kelvin scale) for 2 h and subsequently holding at 760 °C for 16 h. Due to the consumption of γ′ forming elements, Ti and Al, by the formation of the Y{sub 4}Al{sub 2}O{sub 9} and TiN dispersoids, the content of γ′ precipitates in the microstructure of the heat treated sample is significantly reduced, as confirmed by experimentation and calculation using the JMatPro software. Additionally, the size of γ′ precipitates also sharply decreased to 20–30 nm in the heat treated UFG René 88DT-5vol.%Y{sub 2}O{sub 3} alloy, in contrast to a size of 100–150 nm in the Y{sub 2}O{sub 3}-free base alloy under the same heat treatment condition.
- OSTI ID:
- 22805032
- Journal Information:
- Materials Characterization, Journal Name: Materials Characterization Vol. 141; ISSN 1044-5803; ISSN MACHEX
- Country of Publication:
- United States
- Language:
- English
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