A new tungsten-free γ–γ’ Co–Al–Mo–Nb-based superalloy

We present the first report of a tungsten-free cobalt-based superalloy having a composition Co–10Al–5Mo–2Nb. The alloy is strengthened by cuboidal precipitates of metastable Co3(Al,Mo,Nb) distributed throughout the microstructure. The precipitates are coherent with the face-centred cubic γ-Co matrix and possess ordered L12 structure. The microstructure is identical to the popular γ–γ’ type nickel-based superalloys and that of recently reported Co–Al–W-based alloys. Being tungsten free, the reported alloy has higher specific proof stress compared to existing cobalt-based superalloys.

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