Influence of small copper additions on the phase formation and the coercivity of rapidly quenched Nd-Fe-Callos

다국어 초록 (Multilingual Abstract)

In order to improve magnetic properties of Nd-Fe carbide magnets, small amount of copper (≤2.0 at.%) was added to melt-spun iron-rich Nd-Fe-C alloys and its effect on the microstructural development and the coercivity of the alloys was investigated. It was found that the overall transition temperatures for phase transformations in the alloys were lowered as the copper addition increased. Furthermore, amorphization of α-Fe and/or Nd_(2)Fe_(17)C_(χ) in the as-spun state was retarded even at 40 m/s with the increase of copper content. Then the residual α-Fe or Nd_(2)Fe_(17)C_(χ) did not eliminated completely after an annealing within 10 min at the optimum temperature range. The grain size of Nd₂Fe14C increased with the increase of Cu addition and the abnormal grain growth of the square-shaped grains was often found in the alloys annealed for more than 10 min above 800℃. By adding 0.5 at.% Cu, intrinsic coercivities of more than 14 kOe, which were 40%-50% higher than that (∼10 kOe) of copper-free alloys, could be obtained after annealing at 750-800℃.

목차 (Table of Contents)

• 1. Experimental
• 2. Results and Discussion
• 3. Conclusions
• References