A mechanism of plane matching boundary-assisted α/γ phase transformation in Fe–Cr alloy based on in-situ observations

Abstract On the basis of in-situ observations of the α/γ phase transformation in an iron-4.2 at.% Cr alloy, it was found that triple junctions with more random boundaries can be preferential sites for nucleation and that a two-stage migration of α/γ interphase boundaries can occur with highly different velocities, i. e. of 0.23 ∼ 0.43 µm/sec for the α/γ two phase temperature region and 2.6 ∼ 44 µm/sec for the γ single phase region. The origin of the observed high migration velocities of α/γ interphase boundaries and the generalized K-S orientation relationship between a new phase and the matrix are discussed on the basis of a possible role of {111}γ//{110}α plane matching interphase boundaries in the α/γ phase transformation.