Chemical Partitioning During Crystallization and its Effect on the Microstructure and Magnetic Behavior of Modified Nd–Fe–B Permanent Magnets

Authors

Jeffrey E. Shield, University of Nebraska-LincolnFollow
B. B. Kappes, University of Utah, Salt Lake City, UT
D. J. Branagan, Idaho National Engineering and Environmental Laboratory
J. Bentley, Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN

Date of this Version

2002

Comments

Published in Journal of Magnetism and Magnetic Materials 246 (2002) 73–79. Copyright 2002. Used by permission.

Abstract

In this paper, the effect of alloy composition on the microstructural development of devitrified Nd–Fe–B-based alloys is investigated. While crystallization of simple ternary Nd₂Fe₁₄B resulted in a highly variable microstructure and relatively poor demagnetization behavior, alloying additions, notably Ti and C, were found to significantly refine and homogenize the crystallized microstructure. High spatial resolution energy dispersive X-ray spectroscopy revealed that partitioning to the grain boundaries led to the grain refinement by slowing interface kinetics. The more homogeneous grain structure resulted in improved demagnetization behavior, but segregating elements isolated grains and limited intergranular exchange coupling.