メカニカルグラインディングによるNdFeB系合金粉末の硬質磁気特性

抄録

Mecaeical grinding and subsequent heat treatment on the Nd₁₅Fe₇₇B₈ alloy powder made by means of centrifugal atomization causes high coercive force equal to the known value by former methods. The transition of magnetic properties during these process was studied by apparent specific heat and X-ray analysis. Mechanical grinding for 6 hours keeps the state of preceeding process to amorphous. Change to amorphous state is improved by mechanical grinding for 12-24 hours. The crystallization makes progress by subsequent heat treatment at 450-500°C. It was concluded that the high coercive force was obtained during the crystallization. After heat treatment at 600°C, advance of crystallization causes the lower coercive force.
Similar change of magnetic properties was also observed for the Nd₁₃Dy₂Fe₇₇B₈ alloy power.