Magnetic behavior of Sm-Co-based permanent magnets during order/disorder phase transformations

Authors

Shampa Aich, University of Nebraska - LincolnFollow
J. Kostogorova, University of Nebraska - Lincoln
Jeffrey E. Shield, University of Nebraska - LincolnFollow

Date of this Version

5-11-2005

Comments

Published by Am Inst of Physics. J. Appl. Phys. 97, 10H108 (2005). Copyright 2005. Permission to use. http://www.aip.org/.

Abstract

The structural transformation from the metastable disordered TbCu₇-type SmCo₇ structure to the equilibrium ordered Th₂Zn₁₇-type Sm₂Co₁₇ structure was revealed by x-ray diffraction analysis using Reitveld refinement. The magnetic properties depended strongly on the stage of the transformation, as the coercivity strongly depended on the annealing temperature. The as-solidified alloy in the TbCu7-type structure had a coercivity of 4 kOe, which increased to greater than 9 kOe. The coercivity decreased to around 5 kOe as the transformation neared completion upon annealing at higher temperatures. The magnetization processes were also strongly influenced by the structural state. Initially it was totally controlled by nucleation followed by the domain wall pinning-controlled magnetization process.