A NEW PROCESS FOR ND-FE-B POWDER AND MAGNETS

4.1 Conventionally Processed Powder During exposure to the dry and humid environments, conventionally processed powder developed oxide phases that increased the weight of the powder. The oxide phases developed as a result of the chemical reaction between neodymium and iron and oxygen absorbed from the surrounding atmosphere. 4.2 AQUANIDE-Processed Powder The AQUANIDE-processed powder developed a small amount of oxide phase on the surface of the powder particles, slightly reducing the alignment in a magnetic field. The powder has a very low susceptibility to corrosion, and the magnetic properties remain stable over an extended period of time. Magnets made from AQUANIDE powder that had been stored in a normal laboratory air atmosphere for extended periods of time showed no appreciable degradation in magnetic properties. The results of this study clearly demonstrate the superior corrosion resistance of AQUANIDE-processed Nd-Fe-B powder compared to conventionally processed material. © 1993 ASM International.