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Microstructure and magnetic properties of Dy-added Alnico alloys

2023; Elsevier BV; Volume: 973; Linguagem: Inglês

10.1016/j.jallcom.2023.172894

1873-4669

Yueqing Liu, Jiangtao Zhao, Zhihe Zhao, Lei Liu, Min Huang, Bo Zhou, Yong Ding, Yingli Sun, Aru Yan,

Magnetic properties of thin films

Alnico permanent alloys are still irreplaceable and show great potential in high temperature applications considering their excellent thermal stability, while the market for Alnico alloys is limited by their low coercivity. Rare-earth addition has been shown to increase the coercivity of Alnico alloys. In this work, the effects of Dy-addition on the crystal structure, microstructure, spinodal decomposition phases and magnetic characteristics of Alnico alloys were systematically investigated. The results indicate that the Dy element forms Dy-rich precipitates and influences the morphology and composition of spinodal decomposition structure. The 0.3 wt% Dy addition improves the coercivity from 132 kA·m−1 for the Dy-free alloys to 141 kA·m−1 for the Dy-added alloys and slightly optimizes the thermal stability. The enhancement of coercivity is attributed to the refined and uniform spinodal decomposition structure by reducing the mismatch degree and coherency strain. However, the magnetic properties of the 0.6 wt% Dy added alloy decrease due to the damaged structure with excessive Dy-rich phases and more connected α1 phases. A method for improving coercivity and thermal stability is suggested.