Microstructure and magnetocaloric effect of melt-spun Ni_(52)Mn_(26)Ga_(22) ribbon

摘要

Microstructural features and magnetocaloric properties of Ni_(52)Mn_(26)Ga_(22) melt-spun ribbons were studied. Results show that there are four types of differently oriented variants of seven-layered modulated (7M) martensite at room temperature, being twin-related one another and clustered in colonies. Due to the coupled magnetic and structural transformations between parent austenite and 7M martensite, the melt-spun ribbons exhibit a significant magnetocaloric effect. At an applied magnetic field of 5 T, an absolute maximum value of the isothermal magnetic entropy change of 11.4 J kg~(-1) K~(-1) is achieved with negligible hysteresis losses.