2ISTerre - Institut des Sciences de la Terre (ISTerre, OSUG-C (Maison des Géosciences), 1381, rue de la Piscine, 38610 GIERES
ISTerre, Université Savoie Mont Blanc, Campus Scientifique, 73376 Le Bourget-du-Lac Cedex - France)
Abstract : 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.
https://hal.univ-lille.fr/hal-02937692
Contributeur : Lilloa Université de Lille <>
Soumis le : lundi 14 septembre 2020 - 12:07:18 Dernière modification le : mercredi 30 décembre 2020 - 13:08:07 Archivage à long terme le : : jeudi 3 décembre 2020 - 03:48:33