In Situ Investigation of the Allotropic Transformation in Iron

Abstract Previous studies on the allotropic transformation in iron suggested a high transformation temperature and a controversial transformation mechanism. At present, however, our understanding of the transformation characteristics in iron seems insufficient, especially as there is a general lack of in situ data on morphological evolution and lattice parameter changes during the transformation. In this study, the characteristics of the morphology, the crystallographic relationships, and short‐range diffusion in the allotropic transformation are investigated systematically on the basis of in situ and ex situ observations using time resolved X‐ray diffraction, laser scanning confocal microscopy, and electron backscattering diffraction. In contrast to the martensitic transformation, the characteristics of the allotropic transformation will be highlighted. Finally, the results are compared with previous reports in order to provide further insight into the nature of the phase transformation based on the in situ observations.