Abstract: The precipitation behavior of χ phase and M₂₃C₆ carbide in low-activation duplex phase multi-principal element alloy Fe₅₁Mn₃₀Cr₁₉ after tempering at 475 ℃ were studied by means of XRD, SEM, EBSD and TEM. The result shows that, after tempering, the precipitation behavior of χ phase and M₂₃C₆ carbide in the test materials exists similarities as well as differences. The similarities of the two precipitates are both exhibited the same cubic-cubic orientation relationship with its matrix, and the ratio of lattice constant of the precipitates and matrix is very close to 3∶1. However, the differences of the two precipitates are that χ phase is first precipitated inside the ferrite in the form of a dot-like, and there is no element segregation in the precipitation process, but the M₂₃C₆ phase always begins to precipitate at the interface of ferrite/austenite, and then gradually to expand into the ferrite region, which has a significant segregation of chromium. Based on the lattice structure of the two precipitations and their relationship with their parent phase, the formation mechanism of the two precipitations is also analyzed. Through the analysis of these characteristics of low-activation duplex phase multi-principal element alloy, it can provide an important reference for the control of the precipitated phase and the design of material properties.

Key words: multi-principal element alloy, reduced-activation, χ phase, M₂₃C₆ carbide, orientation relationship