MAGNETIC HARDENING OF CR- W-ADDED NDDYFECOB SINTERED MAGNETS/

The addition of 2 at% Cr or W into a sintered (Nd,Dy)-(Fe,Co)-B alloy is very effective in improving room temperature coercivity and thermal stability. The W-containing alloy showed twice the coercivity value t o that of W-free alloy at temperatures higher than 100-degrees-C. Both W and Cr alloying greatly improve the high temperature stability. The m exists a WFeB precipitate phase in the W-containing alloy. The WFeB phase is platelet with its long axis parallel to c-axis of the 2-14-1 phase. The domain wall pinning at the precipitate phase, as evidenced by the Lorentz microscopy, is the mason of enhanced coercivity of this alloy, particularly at high temperatures.