2008 Volume 49 Issue 12 Pages 2770-2775
The in-situ SEM/EBSD technique has been applied to observe the dynamics of ferrite(α) → austenite(γ) phase transformation and to examine the orientation relationship between α and γ phases in an Fe-9.5 at% Ni alloy. Random grain boundaries and grain-boundary triple junctions were found to act as preferential nucleation sites for γ phase. The effectiveness of triple junctions as the γ phase nucleation site in phase transformation increased with increasing number of random boundaries intersecting at a triple junction. Approximately 90% of allotriomorphic γ phase possessed either a Kurdjumov-Sachs (K-S) or a Nishiyama-Wasserman (N-W) orientation relationship (OR) with the α parent grains. The γ allotriomorphs with a special OR with one of the adjoining α parent grains preferentially grew into the α grain having the special OR with them, while the allotriomorphs with special ORs with both of the α grains grew into both adjoining α grains symmetrically.
