Physical Review B, 91, 174105, (2015) [doi: 10.1103/PhysRevB.91.174105]
Mechanism of the α−ε phase transformation in iron
A. Dewaele, C. Denoual, S. Anzellini, F. Occelli, M. Mezouar, P. Cordier, S. Merkel, M. Véron, and E. Rausch
The α-Fe↔ε-Fe pressure-induced transformation under pure hydrostatic static compression has been characterized with in situ x-ray diffraction using α-Fe single crystals as starting samples. The forward transition starts at 14.9 GPa, and the reverse at 12 GPa, with a width of α−ε coexistence domain of the order of 2 GPa. The elastic stress in the sample increases in this domain, and partially relaxes after completion of the transformation. Orientation relations between parent α-Fe and child ε-Fe have been determined, which definitely validates the Burgers path for the direct transition. On the reverse transition, an unexpected variant selection is observed. X-ray diffraction data, complemented with ex situ microstructural observations, suggest that this selection is caused by defects and stresses accumulated during the direct transition.
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