On the tetragonality of martensites in ferrous shape memory alloy Fe3Pt: A first-principles study

: Song Lu

Publisher: PERGAMON-ELSEVIER SCIENCE LTD

: 2016

: Acta Materialia

: ACTA MATERIALIA

: ACTA MATER

: 111

: 56

: 65

: 10

: 1359-6454

: 1873-2453

DOI: https://doi.org/10.1016/j.actamat.2016.03.056

First-principles calculations have been performed to study the effects of point defects on the tetragonality of martensites in ferrous shape memory alloy Fe3Pt. By computing the Bain path, I show that by. considering point defects, all the face-centered cubic (fct) and body-centered cubic (bct) phases with c/a values close to the experimental observations are predicted. Atomic structure analysis gives evidence about the proposed "antiferrodistortive transformation" which was previously derived from the softened phonon mode of Fe3Pt. We discuss the dependence of the Bain path on the concentration of defects and show that the observed bct structures are closely related to the particular shape of the L1(2) Bain path. Magnetism is identified as the origin of the extremely flat Bain path. The role of the enhanced band Jahn-Teller effect in stabilizing the fct phases is discussed. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.