Stress-induced transition from modulated 14M to non-modulated martensite in Ni–Mn–Ga allo

0455296 - FZÚ 2016 RIV GB eng J - Článek v odborném periodiku
Ge, Y. - Zárubová, Niva - Heczko, Oleg - Hannula, S.-P.
Stress-induced transition from modulated 14M to non-modulated martensite in Ni–Mn–Ga allo.
Acta Materialia. Roč. 92, May (2015), s. 151-160. ISSN 1359-6454. E-ISSN 1873-2453
Grant CEP: GA ČR(CZ) GAP107/11/0391; GA ČR GAP107/12/0800; GA MŠMT(CZ) LM2011026
Institucionální podpora: RVO:68378271
Klíčová slova: Ni-Mn-Ga * in situ TEM * magnetic shape memory * twinning dislocation * intermartensitic transition
Kód oboru RIV: BM - Fyzika pevných látek a magnetismus
Impakt faktor: 5.058, rok: 2015

In situ straining of seven-layered (14M) martensite of Ni-Mn-Ga alloy was done with transmission electron microscope (TEM). During straining, the intermartensitic transition from 14M to non-modulated martensite (NM) occurred via motion of partial dislocation with a Burgers vector b = 1/6[1 (1) over bar 0] along the basal plane of 14M. High resolution TEM studies revealed that the moving partial at the end of the fault is actually a pair of partial dislocations leading to a two-layered fault. The fault is twin related to the adjoining five-layered basal plane forming complete seven-layered nanotwinned structure. Results demonstrate that the 14M to NM transition is a detwinning process of these nanotwins, and seems to confirm the nanotwin nature of the long-period stacking-order structure of 14M martensite. Lattice parameters of the average structure are affected by the regularity of the stacking sequence, i.e., by the volume fraction of the two-layer nanotwins and their distribution.
Trvalý link: http://hdl.handle.net/11104/0255926