Martensitic transformation and damping capacities of Ni50Mn40–xSn10+x (x = 0–4 at.%) ferromagnetic shape memory alloys

Martensitic transformation and damping capacities of inherent and intrinsic internal frictions (IFPT + IFI) of Ni50Mn40-xSn10+x (x = 0–4 at.%) ferromagnetic shape memory alloys (FSMAs) are investigated. The (IFPT + IFI)L21→14M peak height of Ni50Mn40Sn10 FSMA is higher than the other Ni50Mn40-xSn10+x FSMAs as there are more abundant movable twins dissipating energy during damping in 14M martensite than in 10M or 4O martensite. The Ni50Mn38Sn12 FSMA exhibits a lower (IFPT + IFI)L21→10(majority)+14M(minority) peak than the (IFPT + IFI)L21→4O peak of the Ni50Mn37Sn13 FSMA as there is a smaller number of movable twins in the 10M martensite than in the 4O martensite. Compared with the other SMAs, Ni50Mn40-xSn10+x FSMAs with 14M martensite not only exhibit a high damping at temperatures above 100 °C but also possess the advantage of easily controlling the transformation temperature by adjusting the Sn content of the alloy.