Magnetic shape-memory alloys are considered to be active materials enabling rapid, large-strain actuation upon application of a magnetic field. This is due to twin boundaries movement under the influence of an internal stress produced by magnetic anisotropy energy, and is not recovered upon removal of the field. Magnetoplasticity has been extensively studied for off-stoichiometric MnGa Heusler alloys (e.g.,), which as single crystals exhibit large magnetoplastic strains (up to 10% when optimally oriented to the magnetic field) due to deformation by twinning and a large magnetic anisotropy constant. Since the growth of Ni-Mn-Ga single crystals is slow and leads to severe segregation, affecting local composition, crystal structure, and magnetoplastic strain we have adopted a way of synthesis of the NiMnGa via arc-melting. This, followed by subsequent annealing of alloys, mitigated the problem of segregation. Subsequent liquid melt infiltration into a sodium aluminate-based foam resulted in a polycrystalline magnetic shape-memory alloys with single and bimodal open porosity that can exhibit magnetoplastic strains (produced solely by magnetic forces at constant temperature and without mechanical bias stress) negligibly small as compared to single-crystal values.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 1247327