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稀土元素具有相似的基态电子性质,其独特的镧系收缩效应可以降低高熵材料中稀土元素的混合焓,这对于制备廉价且高性能的高熵稀土金属间化合物至关重要。本文在分析磁化和反磁化曲线的基础上,辅以Henkel曲线和磁粘滞系数S计算,研究了Nd11.76Fe82.36B5.88(NdFeB),以及高熵稀土永磁合金化合物(La0.2Pr0.2Nd0.2Gd0.2Dy0.2)11.76Fe82.36B5.88和(La0.2Pr0.2Nd0.2Gd0.2Tb0.2)11.76Fe82.36B5.88等快淬条带的反磁化机理。研究结果发现,与纯NdFeB相比,高熵稀土永磁材料的晶间耦合作用显著增强,而磁偶极相互作用减弱。这表明,含重稀土的高熵材料中元素扩散机制在使样品均匀化的同时,其矫顽力有大幅度提高,矫顽力机制为硬磁相晶粒中的反磁化畴形核。(La0.2Pr0.2Nd0.2Gd0.2Dy0.2)11.76Fe82.36B5.88的磁粘滞系数大于纯NdFeB,(La0.2Pr0.2Nd0.2Gd0.2Tb0.2)11.76Fe82.36B5.88由于硬磁相反转与磁晶间耦合作用不同步,导致样品在具有较大各向异性场的同时,磁粘滞系数较小。这表明,高熵稀土永磁材料与传统稀土永磁材料的反磁化机理有显著不同,值得进一步深入研究。Rare-earth elements share similar ground-state electronic properties, and their unique lanthanide contraction effect can lower the mixing enthalpy of rare-earth elements in high-entropy materials, which is of paramount importance for the fabrication of low-cost and high-performance high-entropy rare-earth intermetallic compounds. In this paper, the magnetization reversal mechanisms of rapidly quenched ribbons such as Nd11.76Fe82.36B5.88 (NdFeB) and the relevant high-entropy rare-earth permanent magnet alloy compounds (La0.2Pr0.2Nd0.2Gd0.2Dy0.2)11.76Fe82.36B5.88and (La0.2Pr0.2Nd0.2Gd0.2Tb0.2)11.76Fe82.36B5.88were studied by analyzing the magnetization and demagnetization curves, supplemented by Henkel curves and magnetic viscosity coefficient S. Compared to the pure NdFeB sample, the inter-grain exchange coupling in high-entropy rare-earth permanent magnets is significantly enhanced, while the magnetic dipole interaction is weakened, indicating that the element diffusion mechanism in heavy rare-earth containing high-entropy materials homogenizes the sample, and significantly increases the coercivity. The mechanism of the coercivity is the nucleation of magnetization reversal domains in the grains of the hard magnetic phase. The magnetization mechanism is dominated by pinning at low magnetic fields and by nucleation at high magnetic fields, which is different from the magnetization mechanism of pure NdFeB and has some similarities with the self-pinning mechanism. The magnetic viscosity coefficient of (La0.2Pr0.2Nd0.2Gd0.2Dy0.2)11.76Fe82.36B5.88 is larger than that of pure NdFeB. Due to the asynchrony of hard magnetic phase reversal and intergranular magnetic coupling in (La0.2Pr0.2Nd0.2Gd0.2Tb0.2)11.76Fe82.36B5.88, the magnetic viscosity coefficient is small with a large anisotropy field. This indicates that high-entropy samples reduce the magnetocrystalline anisotropy field barrier while increasing the magnetocrystalline coupling length. This suggests that the magnetization reversal of high-entropy rare-earth permanent magnet materials are significantly different from those of conventional rare earth permanent magnet materials and warrant further in-depth studies.
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Keywords:
- High-entropy permanent magnets /
- Henkel /
- intergrain exchange coupling /
- magnetic viscosity coefficient
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