List of publications
Physical Review B, 102, 104103, (2020) [doi: 10.1103/PhysRevB.102.104103]
Microstructural effects and mechanism of bcc-hcp-bcc transformations in polycrystalline iron
S. Merkel, A. Lincot, S. Petitgirard
Cycling the α↔ε transformation in polycrystalline Fe is investigated using in situ x-ray diffraction under quasihydrostatic conditions. The forward α→ε transformation starts at 14±1 GPa and completes at 18±1 GPa while the reverse ε→α transformation starts at 10.5±0.5 GPa and completes at 6±1 GPa. The anomalous evolution of c/a ratios of ε-Fe measured at the onset of the α→ε transition in earlier studies is not observed. Microstructural features are consistent with a Burgers path for the transformation. The forward α→ε transformation is sensitive to the average and intergranular stresses, inducing a strong variant selection with the c axes of the new ε phase preferentially aligned perpendicular to compression and concentrated into one single orientation. Partial texture memory is observed as the sample returns to the α phase but, as transformation cycles go on, irreversible changes occur in the microstructures that are later fully induced by the cycles of phase transformations.
Full text of this article is available online.