Martensitic transformation and damping capacities of Ni_(50)Mn_(40-x)Sn_(10+x) (x=0-4 at.%) ferromagnetic shape memory alloys

摘要

Martensitic transformation and damping capacities of inherent and intrinsic internal frictions (IF_(PT)+IF,) of Ni_(50)Mn_(40-x)Sn_(10+x) (x=0-4 at.%) ferromagnetic shape memory alloys (FSMAs) are investigated. The (IF_(PT)+IF,)_(L21→14M) peak height of Ni_(50)Mn_(40)Sn_(10) FSMA is higher than the other Ni_(50)Mn_(40-x)Sn_(10+x) FSMAs as there are more abundant movable twins dissipating energy during damping in 14M martensite than in 10M or 4O martensite.The Ni_(50)Mn_(38)Sn_(12) FSMA exhibits a lower (IF_(PT)+IF_I)_(L21→10(majority)+14M(minority)) peak than the (IF_(PT)+IF_I)_(L21→4O) peak of the Ni_(50)Mn_(37)Sn_(13) FSMA as there is a smaller number of movable twins in the 10M martensite than in the 40 martensite. Compared with the other SMAs, Ni_(50)Mn_(40-x)Sn_(10+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.