Effects of heat treatment on the microstructure and mechanical properties of Ni₃Al-based superalloys: A review

Ni₃Al-based alloys have drawn much attention as candidates for high-temperature structural materials due to their excellent comprehensive properties. The microstructure and corresponding mechanical properties of Ni₃Al-based alloys are known to be susceptible to heat treatment. Thus, a significant step is to employ various heat treatments to derive the desirable mechanical properties of the alloys. This paper briefly summarizes the recent advances in the microstructure evolution that occurs during the heat treatment of Ni₃Al-based alloys. Aside from γ′ phase and γ phase, the precipitations of β phase, α-Cr precipitates, and carbides are also found in Ni₃Al-based alloys with the addition of various alloying elements. The evolution in morphology, size, and volume fraction of various types of secondary phases during heat treatment are reviewed, involving γ′ phase, β phase, α-Cr precipitate, and carbides. The kinetics of the growth of precipitates are also analyzed. Furthermore, the influences of heat treatment on the mechanical properties of Ni₃Al-based alloys are discussed.