In-Situ SEM/EBSD Observation of α/γ Phase Transformation in Fe-Ni Alloy

The in-situ SEM/EBSD technique has been applied to observe the dynamics of ferrite(� ) ! austenite(� ) phase transformation and to examine the orientation relationship betweenandphases in an Fe-9.5 at% Ni alloy. Random grain boundaries and grain-boundary triple junctions were found to act as preferential nucleation sites forphase. The effectiveness of triple junctions as thephase nucleation site in phase transformation increased with increasing number of random boundaries intersecting at a triple junction. Approximately 90% of allotriomorphicphase possessed either a Kurdjumov-Sachs (K-S) or a Nishiyama-Wasserman (N-W) orientation relationship (OR) with the � parent grains. Theallotriomorphs with a special OR with one of the adjoiningparent grains preferentially grew into thegrain having the special OR with them, while the allotriomorphs with special ORs with both of thegrains grew into both adjoininggrains symmetrically. (doi:10.2320/matertrans.MAW200824)

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