Ni-Mn-Ga(-Fe) system exhibit interesting evolution between commensurate and incommensurate modulated structures of martensite. In this publication, we study the effect of temperature and tensile loading. We show that the transition between the commensurate and incommensurate state is associated also with the change of lattice symmetry from monoclinic to orthorhombic. Moreover, we show that the incommensurate structure is surprisingly stable upon tensile loading, till some critical deformation, after which an irreversible transition to commensurate structure is initiated. The results are important for understanding the details of the complex crystal structure of the material, high mobility of twin boundaries, and for the interpretation of the modulated crystal structure of martensite as an ensemble of nanotwins.
Vinogradova, M., Sozinov, A., Straka, L., Veřtát, P., Heczko, O., Zelený, M., Chulist, R. and Ullakko, K. (2024). Stability of incommensurately modulated Ni50Mn27Ga22Fe1 10M martensite under uniaxial tensile stress. Scripta Materialia, 247, 116096.
https://doi.org/10.1016/j.scriptamat.2024.116096
