In situ TEM study of deformation twinning in Ni-Mn-Ga non-modulated martensite

0395811 - FZÚ 2014 RIV GB eng J - Článek v odborném periodiku
Zárubová, Niva - Ge, Y. - Heczko, Oleg - Hannula, S.-P.
In situ TEM study of deformation twinning in Ni-Mn-Ga non-modulated martensite.
Acta Materialia. Roč. 61, č. 14 (2013), s. 5290-5299. ISSN 1359-6454. E-ISSN 1873-2453
Grant CEP: GA ČR(CZ) GAP107/11/0391; GA MŠMT(CZ) LM2011026; GA ČR GAP107/12/0800; GA AV ČR IAA100100920
Institucionální podpora: RVO:68378271
Klíčová slova: Ni-Mn-Ga * in situ TEM * magnetic shape memory * deformation twinning * twinning dislocation
Kód oboru RIV: BM - Fyzika pevných látek a magnetismus
Impakt faktor: 3.940, rok: 2013

The straining of non-modulated (NM) Ni–Mn–Ga martensite was studied by in situ transmission electron microscopy (TEM). Initially, the self-accommodated NM martensitic structure consists of internally twinned domains. During straining, the detwinning process starts within these domains. The internal twin variant more favorably oriented to the stress grows at the expense of the other one. In the detwinned, single-variant domain, a new twin variant can form, gradually replacing the existing variant via the twinning process. Both processes—detwinning and new twinning—proceed by the same mechanism, namely by the movement of twinning dislocations along the twin boundary. Lattice dislocations are also created in the detwinning process. While the boundaries between the internal twins are coherent and mobile, the boundaries between the internally twinned domains are incoherent, strained and not mobile. Possible reasons for this discrepancy are discussed.
Trvalý link: http://hdl.handle.net/11104/0223728