晶界扩散Dy60Co35Ga5合金对烧结钕铁硼磁体 磁性能及热稳定性的影响

研究了晶界扩散Dy₆₀Co₃₅Ga₅合金对烧结钕铁硼磁体磁性能及其热稳定性的影响.随着扩散温度的升高，磁体的矫顽力（H_cj）呈现出先增加后减少的趋势，并在890 ℃扩散3 h，480 ℃回火5 h的工艺条件下，矫顽力达到较优，从1 209 kA/m提高到1 624 kA/m，磁体的剩磁只有轻微的下降，从1.38 T降低到1.32 T.高温下测试磁体的磁性能，原始磁体和890 ℃晶界扩散Dy₆₀Co₃₅Ga₅合金磁体的矫顽力都呈下降趋势，但晶界扩散Dy₆₀Co₃₅Ga₅合金磁体的矫顽力在高温下要明显优于原始磁体.原始磁体及890 ℃晶界扩散Dy₆₀Co₃₅Ga₅合金磁体在不同温度下保温2 h的不可逆磁通损失分别为63 %和45 %.且DSC结果显示，890 ℃晶界扩散Dy₆₀Co₃₅Ga₅合金磁体的居里温度（T_c）要明显高于原始磁体的居里温度，这表明晶界扩散磁体的热稳定性得到了很大的改善. XRD图谱显示，890 ℃晶界扩散磁体RE₂Fe₁₄B相的衍射峰较原始磁体向右偏移，说明Dy原子及Co原子少部分已进入主相晶粒. 

Effect of grain boundary diffusion Dy60Co35Ga5 alloys on magnetic properties and thermal stability of sintered NdFeB magnets

The effect of grain boundary diffusion Dy₆₀Co₃₅Ga₅ alloys on the magnetic properties and thermal stability of sintered NdFeB magnets was investigated. As diffusion temperature rose, the coercivity (H_cj) of the magnets first increased and then decreased. After the magnets were under diffusion treatment at 890 ℃ for 3 h and were annealed subsequently at 480 ℃ for 5 h, the coercivity reached maxima, increasing from 1 209 kA/m to 1 624 kA/m. At the same time, the remanence of the diffused magnets decreased slightly, from 1.38 T to 1.32 T. When magnetic properties of the original magnet and the grain boundary diffusion Dy₆₀Co₃₅Ga₅ alloy one were tested at high temperatures respectively, the two magnets both showed decrease in coercivity. But the coercivity of the diffused magnet was significantly higher than that of the original one. After the original magnet and the diffused one were exposed to different temperatures for 2 h, magnets′ irreversible flux loss stood 63 % and 45 %, respectively. According to the differential scanning calorimeter (DSC) results, the Curie temperature (T_c) of the diffused magnet was significantly higher than that of the original one, which indicated that the thermal stability of the diffused magnet has been greatly improved. Besides, the X-ray diffraction (XRD) pattern of the diffused magnet showed that its diffraction peaks of RE₂Fe₁₄B phase shifted to the right, compared to the original one. This suggested that a small number of the Dy atoms and Co atoms have entered the main phase grain.