Strain glass behaviour of Ni–Co–Mn–Sn ferromagnetic shape memory alloys

We report the direct experimental observations of the glassy behaviour in Ni–Co–Mn–Sn ferromagnetic shape memory alloys by doping sufficient substitutional point defect Co into the Ni sites (9 at%). The results showed that high level of Co doping had caused the complete suppression of the martensitic transformation and introduction of a strain glass transition in Ni–Co–Mn–Sn alloys. The strain glass transition was definitively characterized by the dynamic mechanical anomalies following the Vogel–Fulcher relationship and the signature nonergodicity of the frozen glass using a zero‐field‐cooled/field‐cooled heating measurement of static strain. The findings clarified the cause of vanishing of the martensitic transformation in Ni–Co–Mn–Sn alloy with high Co doping levels and the generality of glassy state in Ni–Mn based ferromagnetic shape memory alloys with high level of foreign elements doping. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)