The microstructure and high-temperature properties of novel nano precipitation-hardened face centered cubic high-entropy superalloys

The present work reports two novel γ′(Ni₃Al type)-enhanced high-entropy superalloys Ni_{45 − x}(FeCoCr)₄₀(AlTi)₁₅Hf_x (x = 0, 0.2 at.%) with high-entropy fcc (face centered cubic) matrix and γ′ particles microstructure at cast condition. A large number of γ′ particles, with an average diameter size of 52 nm (dendritic regions) and 90 nm (inter-dendritic regions), are homogeneously distributed in a high-entropy fcc matrix and are coherent with the matrix. Attributable to the γ′ particles, the alloys show prominent mechanical properties at both room temperature and high temperatures. Coherent strength and atomic ordering strength are the primary strengthening mechanisms.