Temperature Evolution of The Modulation Vector in 10M Martensite of Ni-Mn-Ga(-Fe) Alloys
(P. Veřtát)
We discuss the temperature evolution of the structural modulation within the 10M martensite of Ni-Mn-Ga(-Fe) single crystals. Here, the reversible incommensurate-commensurate transition with a thermal hysteresis has been found.
See also and cite as Veřtát, P., Seiner, H., Straka, L., Klicpera, M., Sozinov, A., Fabelo, O., & Heczko, O. (2021). Hysteretic structural changes within five-layered modulated 10M martensite of Ni–Mn–Ga (–Fe). Journal of Physics: Condensed Matter, 33(26), 265404. 10.1088/1361-648x/abfb8f
Universal Temperature Dependence of Twinning Stress in Ni-Mn-Ga 10M Martensite
(L.Straka)
Low twinning stress is a prerequisite for magnetic shape memory functionality in ferromagnetic martensites. We compare Ni50Mn28Ga22 (nominal at.%) single crystals from four different producers to reveal the effect of crystal quality on the twinning stress. For crystals of a decent quality, we find a universal temperature dependence of the twinning stress. The video relates to project publication P3.
See also and cite as Musiienko, D., Nilsén, F., Armstrong, A., Rameš, M., Veřtát, P., Colman, R. H., … & Straka, L. (2021). Effect of crystal quality on twinning stress in Ni–Mn–Ga magnetic shape memory alloys. Journal of Materials Research and Technology, 14, 1934-1944 https://doi.org/10.1016/j.jmrt.2021.07.081
Landau-Energy Landscape Reconstruction for a Ni-Fe-Ga(Co) Shape Memory Alloy
( 
K. Zoubková )
[Award-winning lecture in Most viewed presentation category at Icomat 2022 virtual conference]
This short lecture relates to project publication P2 and future project research using elastic continuum theory. We found that ferromagnetic shape memory single crystals show extreme elastic nonlinearity. Constructing an energy function from the experimentally observed stress-strain responses, i.e. Landau-energy landscape reconstruction, enables to deal with the nonlinearity conveniently. The proposed model captures most key features of the examined alloy, such as the existence of the critical point.
See also and cite as: Zoubková, K., Seiner, H., Sedlák, P., Villa, E., Tahara, M., Hosoda, H., & Chernenko, V. (2022). Non-linear elastic behavior of Ni-Fe-Ga (Co) shape memory alloy and Landau-energy landscape reconstruction. Acta Materialia, 224, 117530. https://doi.org/10.1016/j.actamat.2021.117530
MSM basics & MSM micropump
