Advances in Characterization of Non-Rare-Earth Permanent Magnets: Exploring Commercial Alnico Grades 5-7 and 9

TitleAdvances in Characterization of Non-Rare-Earth Permanent Magnets: Exploring Commercial Alnico Grades 5-7 and 9
Publication TypeJournal Article
Year of Publication2013
AuthorsPalasyuk A, Blomberg E, Prozorov R, Yue L, Kramer MJ, McCallum RW, Anderson IE, Constantinides S
Journal TitleJOM
Volume65
Pages862-869
Date Published07
Type of ArticleArticle
ISBN Number1047-4838
Accession NumberWOS:000320387500010
Keywordsal, alloying elements, atom probe, domain, energy, magnetization, microstructure, phase-decomposition
Abstract

The magnetic domain structure of commercial alnico grades 5-7 and 9 was investigated using a magneto-optical Kerr effect (MOKE) to gain an understanding of their coercivity mechanisms at the micron to millimeter scale. In alnico 5-7, the magnetic domain structure exhibits stripes of alternating high and low induction. Magnetic domains easily cross grain boundaries if neighboring grains have a similar tilt and rotation of their crystallographic axes relative to the magnet body. In contrast for alnico 9, stripe-like magnetic domains are not observed regularly throughout the transverse section; rather, discrete localization of high- and low-induction stripe features are observed. In higher magnification MOKE experiments, i.e., similar to 100 mu m, a zigzag-shaped magnetic domain structure was observed in both alnico 5-7 and 9. The zigzag features are four to five times smaller in size than an average grain of alnico 5-7, implying a pinning mechanism that is caused by structural elements within the grains. Discontinuous and reversible motion on a length scale of a few microns was observed for the zigzag-shaped domains for incremental changes in the applied field of similar to 10 Oe. Complimentary magnetic force microscopy measurements show that there are domain structures on an even smaller scale, i.e., 2 mu m to 100 mu m.

URL<Go to ISI>://WOS:000320387500010
DOI10.1007/s11837-013-0618-z