Ribbon-shaped magnetocaloric materials are favorable to achieve high heat-transfer efficiencies due to their large specific surface area. In this work, Mn50Ni41−xIn9Cox (0 ≤ x ≤ 4) ribbons were prepared using a melt-spinning technique, and the corresponding phase transformation and magnetocaloric properties were studied. The large temperature gradient during melt-spinning caused the initial austenite in the ribbons to form typical columnar-shaped grains with a strong ⟨001⟩A preferred orientation perpendicular to the ribbon plane. After cooling, the ribbons undergo martensitic transformation from cubic austenite to monoclinic eight-layered modulated (8 M) martensite. High angle annular dark field-scanning transmission electron microscopy observations indicate that martensite lattice modulation is inhomogeneous at atomic scales. Co substitution for Ni not only strongly influences the phase transformation temperatures but also greatly enhances ferromagnetic coupling. As a result, an enlarged magnetization difference across the martensitic transformation under a field change of 5 T in the Mn50Ni38In9Co3 ribbon induces a large magnetic entropy change up to 12.1 J kg−1 K–1 and a refrigeration capacity of 197 J kg–1 around room temperature. In addition, a wide operational temperature region up to 31 K is obtained in the Mn50Ni37In9Co4 ribbon due to the enhanced sensitivity of the transformation temperature shift under a magnetic field.

中文翻译：

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Co掺杂Mn-Ni-In熔纺带的相变和磁热效应

带状磁热材料由于其比表面积大，有利于实现高传热效率。在这项工作中，使用熔纺技术制备了 Mn50Ni41−xIn9Cox (0 ≤ x ≤ 4) 带，并研究了相应的相变和磁热性能。熔纺过程中的大温度梯度导致带中的初始奥氏体形成典型的柱状晶粒，具有很强的 ⟨001⟩A 择优取向，垂直于带平面。冷却后，带材经历从立方奥氏体到单斜八层调制 (8 M) 马氏体的马氏体转变。高角度环形暗场扫描透射电子显微镜观察表明，马氏体晶格调制在原子尺度上是不均匀的。Co替代Ni不仅强烈影响相变温度，而且大大增强铁磁耦合。因此，在 Mn50Ni38In9Co3 薄带中，在 5 T 场变化下，马氏体相变的磁化强度差异会引起高达 12.1 J kg-1 K-1 的大磁熵变化和 197 J kg-1 左右的制冷能力。室内温度。此外，由于磁场下转变温度漂移的敏感性增强，Mn50Ni37In9Co4 薄带获得了高达 31 K 的宽工作温度范围。在 Mn50Ni38In9Co3 薄带中，在 5 T 的场变化下，马氏体相变的磁化强度差异会引起高达 12.1 J kg-1 K-1 的大磁熵变化和室温附近 197 J kg-1 的制冷能力。此外，由于磁场下转变温度漂移的敏感性增强，Mn50Ni37In9Co4 薄带获得了高达 31 K 的宽工作温度范围。在 Mn50Ni38In9Co3 薄带中，在 5 T 的场变化下，马氏体相变的磁化强度差异会引起高达 12.1 J kg-1 K-1 的大磁熵变化和室温附近 197 J kg-1 的制冷能力。此外，由于磁场下转变温度漂移的敏感性增强，Mn50Ni37In9Co4 薄带获得了高达 31 K 的宽工作温度范围。