Analysis of Anisotropy Produced by Packed-Rolling in Rapidly-Quenched Nd-Fe-B Powder

We have applied a multi-pass packed-rolling technique to the production of anisotropic Nd-Fe-B-Cu powders from rapidly quenched ribbons. Analysis of the packed-rolling process shows that densification proceeds from the surface of the packed powder-compact and crystallographic alignment proceeds more rapidly at the center. Rolling to a reduction in ribbon thickness of greater than 80% results in a uniform material with a high (BH)max of up to 38 MGOe. The present paper discusses the alignment mechanism, taking into consideration the in ternal stress distribution inside the powder compact under rolling pressure.