Regensburg 2022 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 10: Poster Session 1

MM 10.20: Poster

Monday, September 5, 2022, 18:00–20:00, P2

Effect of increasing Mn content on generalized planar fault energies of Ni-Mn-Ga alloys — •Martin Heczko¹, Petr Šesták², and Martin Zelený¹ — ¹Institute of Materials Science and Engineering, Faculty of Mechanical Engineering, Brno University of Technology, Brno, Czech Republic — ²Institute of Physical Engineering, Faculty of Mechanical Engineering, Brno University of Technology, Brno, Czech Republic

Giant magnetic field induced strain (MFIS) in martensitic phase of Ni-Mn-Ga ferromagnetic shape memory alloy makes this alloy promising for various applications. The reasons for existence of MFIS are the high mobility of twin boundaries combined with large magneto-crystalline anisotropy. We performed our calculations using the spin-polarized DFT method implemented in the Vienna Ab Initio Simulation Package (VASP) to reveal the effect of increasing concentration of excess Mn on formation and propagation of twin boundaries, which can be characterized by changes in generalized planar fault energy (GPFE) curves. Effects of excess Mn local arrangement in Ga sublattice on GPFE curves has been considered as well.

Our results show that the barriers for nucleation and grow of a twin rise with increasing content of Mn. It results in more difficult twin formation and propagation in compositions far from stoichiometry. This effect is even more enhanced if excess Mn atom in Ga sublattice is located exactly in the planar fault.