Abstract: Diffusion of elements and phase transformation of the Fe-Cr-Ni-Al alloy during solution treatment process were studied by means of OM, SEM and other methods, and a JMAK model of γ phase transformation was established by DSC data at different cooling rates. The results show that the matrix phase at room temperature of the as-cast Fe-Cr-Ni-Al alloy is γ phase and δ phase. After solution treatment at 1150 ℃, the content of the γ phase in the alloy increases, and the content of the δ phase decreases. The phase change of δ→γ occurs in the heating stage, and the phase change of γ→δ occurs in the isothermal soaking stage. Through the solution treatment, δ phase and γ phase evolve into a more obvious Cr-rich phase and Ni-rich phase, the difference of Cr and Ni elements between σ phases which located in different positions increases, and the component segregation between σ phases and their matrix decreases gradually. It can be proved by the JMAK model of austenite phase transition that the greater the cooling rate, the lower the starting temperature of the γ phase transition, and the larger the temperature interval of the transition, the greater the energy change caused by the reaction.

Key words: Fe-Cr-Ni-Al alloy, solution treatment, element diffusion, phase transformation, JMAK model