Magnetocaloric Effect of Ni56Mn18.8Ga24.5Gd0.7 Alloy
来源期刊：JOURNAL OF RARE EARTHS2006年第5期
论文作者：Duan Jingfang Huang Peng Long Yi Zhang Zeyu Chang Yongqin Wu Guangheng
Key words：NiMnGa; magnetocaloric effect (MCE); magnetic transition; structural transition; magnetic entropy; rare earths;
Abstract: With the addition of Gd, the Ni56Mn18.8Ga24.5Gd0.7 alloy exhibits non-modulated martensite phase at room temperature. From the illustration of Gd microstructure, it can be found that Gd exists along the subgrain boundaries. Hence,he crystalline size decreases and the mechanical properties improve. Ac-susceptibility results show that Ni56Mn18.8Ga24.5Gd0.7 alloy still undergoes simultaneous structural and magnetic transitions and transforms from ferromagnetic martensitic phase to paramagnetic austenitic phase with increasing temperature. The maximum magnetic entropy change is 13.4 J· (kg· K) - 1 under 1.9 T field at 338 K. The giant magnetocaloric effect found in Ni56Mn18.8Ga24.5Gd0.7 alloy is attributed to the concurrently occurring first-order structural- and magnetic-phase transitions.
Duan Jingfang1，Huang Peng1，Long Yi1，Zhang Zeyu2，Chang Yongqin1，Wu Guangheng3
(1.School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China;
2.Institute of Scientific and Technical Information of China, Beijing 100038, China;
3.State Key Laboratory for Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China)
Abstract:With the addition of Gd, the Ni56Mn18.8Ga24.5Gd0.7 alloy exhibits non-modulated martensite phase at room temperature. From the illustration of Gd microstructure, it can be found that Gd exists along the subgrain boundaries. Hence,he crystalline size decreases and the mechanical properties improve. Ac-susceptibility results show that Ni56Mn18.8Ga24.5Gd0.7 alloy still undergoes simultaneous structural and magnetic transitions and transforms from ferromagnetic martensitic phase to paramagnetic austenitic phase with increasing temperature. The maximum magnetic entropy change is 13.4 J· (kg· K) - 1 under 1.9 T field at 338 K. The giant magnetocaloric effect found in Ni56Mn18.8Ga24.5Gd0.7 alloy is attributed to the concurrently occurring first-order structural- and magnetic-phase transitions.
Key words:NiMnGa; magnetocaloric effect (MCE); magnetic transition; structural transition; magnetic entropy; rare earths;
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