Large rotating magnetocaloric effects in polycrystalline Ni-Mn-Ga melt-spun ribbons

Abstract

In this study, the different wheel speeds Ni53Mn23.5Ga23.5 alloy ribbons were prepared by melt-spun method. The morphology and crystal structure, martensitic phase transformation, magnetocrystalline anisotropy, in situ technique magnetization observation and the magnetic refrigeration capacity resulting were tested. The ratio of the length to width for the columnar crystals is approximately 2.5:1.0 in the sample created at a wheel speed of 12 m s−1, and it increases to 5:1 in the sample produced at a wheel speed of 18 m s−1. It is found that a sample with 18 m s−1 ha−1s−1 a large rotating magnetocaloric effect in polycrystalline alloys, with the results of 2 K with different directions. It can be designed as a working substance for rotary refrigeration machines that make full use of their anisotropic characteristics. The in situ atomic force microscope observation of the technological magnetisation has provided an important exploration for a better understanding of the magnetisation.