In situ phase transformation of Laves phase from Chi-phase in Mo-containing Fe-Cr-Ni alloys

An in situ phase transformation of the Chi (χ) phase to the Laves phase was observed in a Fe-Cr-Ni-Mo model alloy. The morphology, composition, and crystal structure of the χ and Laves phases, and their orientation relationship with the matrix austenite phase were investigated. The resulted Laves phase has larger lattice mismatch with the matrix phase than the χ phase, leading to the increase of local strain fields and the formation of dislocations. This finding is helpful to understand the precipitation behavior of the intermetallic phases in the Mo-containing austenitic stainless steels.