Mechanism of the α -ɛ phase transformation in iron
Abstract
The α -Fe↔ɛ -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 -ɛ 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 ɛ -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.
- Publication:
-
Physical Review B
- Pub Date:
- May 2015
- DOI:
- 10.1103/PhysRevB.91.174105
- Bibcode:
- 2015PhRvB..91q4105D
- Keywords:
-
- 61.50.Ks;
- 07.35.+k;
- 81.30.Kf;
- Crystallographic aspects of phase transformations;
- pressure effects;
- High-pressure apparatus;
- shock tubes;
- diamond anvil cells;
- Martensitic transformations