Microstructure and compression strength of Co-based superalloys hardened by γ' and carbide precipitation

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A Co-based superalloy, Co-9Al-9W (at%), was processed by mechanical alloying by high-energy milling of elemental powders and consolidated by field assisted hot pressing (FAHP). The milled powder particles mainly consist of undissolved bcc-W as well as WC and an Al and W rich fcc-γ Co solid solution. After consolidation and heat treatment a fine grained microstructure with a high fraction of carbides and a γ/γ′ microstructure was obtained. The compressive yield strength at room temperature was found to be 45% higher than that of previously reported results for Co-based superalloys. A similar level of strength was found at 700 °C. These extraordinary properties can be explained due to the multitude of hardening mechanisms that sintered Co-based superalloys possess: γ′ precipitation, carbide formation and the ultra-fine γ-grain size promoted by the fast consolidation technique.
Título de la versión aceptada del artículo: Formation of a γ/γ' microstructure in Co-based superalloys produced by a powder metallurgy route
Co-Al-W superalloys, PM route, Mechanical properties, Nanoindentation, Mechanical milling
Bibliographic citation
Materials Science and Engineering: A, (2018), v. 734, pp.: 437-444.