Grain orientation dependence of the forward and reverse fcc - hcp transformation in FeMnSi-based shape memory alloys studied by in situ neutron diffraction

0535125 - ÚFM 2021 RIV CH eng J - Journal Article
Arabi-Hashemi, A. - Polatidis, E. - Šmíd, Miroslav - Panzner, T. - Leinenbach, C.
Grain orientation dependence of the forward and reverse fcc - hcp transformation in FeMnSi-based shape memory alloys studied by in situ neutron diffraction.
Materials Science and Engineering A Structural Materials Properties Microstructure and Processing. Roč. 782, APR (2020), č. článku 139261. ISSN 0921-5093. E-ISSN 1873-4936
Institutional support: RVO:68081723
Keywords : FeMnSi * Neutron diffraction * Martensite transformation * Schmid factor
OECD category: Pure mathematics
Impact factor: 5.234, year: 2020
Method of publishing: Limited access
https://www.sciencedirect.com/science/article/pii/S0921509320303440?via%3Dihub

The grain orientation dependence of the deformation-induced forward fcc -> hcp and reverse hcp -> fcc martensite transformation of a FeMnSi-based shape memory alloy was studied by in situ neutron diffraction during cyclic loading. A deformation-induced fcc -> hcp transformation is observed during tensile straining to +2%. The hcp martensite phase that forms under tension partially reverts to fcc austenite upon subsequent compression from +2% -> -2% for the {220}, {331} and {111} grain families aligned with respect to the loading direction but not for the {200} grain family. The martensite formation and the reversion of the individual grains can be explained by considering grain orientation dependent Schmid factors of the {111} 112 slip system underlying the fcc to hcp transformation. While for post-yield elastically compliant grains the Schmid factor of the leading partial dislocation is larger than that of the trailing partial dislocation, the opposite is true for post-yield elastically stiff grains. The former grains show a phase reversion, i.e. hcp -> fcc upon compression, the latter grains do not transform back to fcc. EBSD characterization confirms the phase reversion for a 541 orientated grain by the disappearance of hcp bands. Martensite bands, which have not reverted to austenite during compression, showed a thickening. The thickening of existing bands during compression is associated with the activation of a second slip system.
Permanent Link: http://hdl.handle.net/11104/0313221