Anisotropic exchange in Nd–Fe–B permanent magnets. Issue 3 (3rd March 2020)

• Record Type: Journal Article
• Authors: Gong, Qihua; Yi, Min; Evans, Richard F. L.; Gutfleisch, Oliver; Xu, Bai-Xiang
• Is Part Of: Materials research letters. Volume 8:Issue 3(2020)
• Page Start: 89
• Page End: 96
• Publication Date: 2020-03-03
• Subjects: Permanent magnets -- grain boundary -- interface exchange -- coercivity -- multiscale simulations; Materials science -- Research -- Periodicals; Biomedical materials -- Research -- Periodicals; Composite materials -- Research -- Periodicals; Biomedical materials -- Research; Composite materials -- Research; Materials science -- Research; Periodicals; 620.1105
• DOI: 10.1080/21663831.2019.1702116
• Languages: English
• ISSNs: 2166-3831

Abstract

ABSTRACT: The exchange is critical for designing high-performance Nd–Fe–B permanent magnets. Here we demonstrate through multiscale simulations that the exchange in Nd–Fe–B magnets, including bulk exchange stiffness ( A e ) in Nd2 Fe14 B phase and interface exchange coupling strength ( J i n t ) between Nd2 Fe14 B and grain boundary (GB), is strongly anisotropic. A e is larger along crystallographic a / b axis than along c axis. Even when the GB Fex Nd1– x has the same composition, J i n t for (100) interface is much higher than that for (001) interface. The discovered anisotropic exchange is shown to have profound influence on the coercivity. These findings enable more freedom in designing Nd–Fe–B magnets by tuning exchange. GRAPHICAL ABSTRACT: IMPACT STATEMENT: Bulk exchange stiffness in Nd2 Fe14 B and interface exchange coupling strength between Nd2 Fe14 B and grain boundary are found strongly anisotropic, which have profound influence on the coercivity of Nd–Fe–B magnets.