Synthesis of single-phase L10-FeNi magnet powder by nitrogen insertion and topotactic extraction

Sho Goto; Hiroaki Kura; Eiji Watanabe; Yasushi Hayashi; Hideto Yanagihara; Yusuke Shimada; Masaki Mizuguchi; Koki Takanashi; Eiji Kita

doi:10.1038/s41598-017-13562-2

Synthesis of single-phase L1₀-FeNi magnet powder by nitrogen insertion and topotactic extraction

Sci Rep. 2017 Oct 16;7(1):13216. doi: 10.1038/s41598-017-13562-2.

Authors

Sho Goto¹, Hiroaki Kura², Eiji Watanabe², Yasushi Hayashi², Hideto Yanagihara³, Yusuke Shimada⁴, Masaki Mizuguchi⁴, Koki Takanashi⁴, Eiji Kita^{3

5}

Affiliations

¹ Advanced Research and Innovation Center, DENSO Corporation, Aichi, 470-0111, Japan. sho_goto@denso.co.jp.
² Advanced Research and Innovation Center, DENSO Corporation, Aichi, 470-0111, Japan.
³ Institute of Applied Physics, University of Tsukuba, Ibaraki, 305-8573, Japan.
⁴ Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.
⁵ National Institute of Technology, Ibaraki College, Ibaraki, 312-8508, Japan.

Abstract

Tetrataenite (L1₀-FeNi) is a promising candidate for use as a permanent magnet free of rare-earth elements because of its favorable properties. In this study, single-phase L1₀-FeNi powder with a high degree of order was synthesized through a new method, nitrogen insertion and topotactic extraction (NITE). In the method, FeNiN, which has the same ordered arrangement as L1₀-FeNi, is formed by nitriding A1-FeNi powder with ammonia gas. Subsequently, FeNiN is denitrided by topotactic reaction to derive single-phase L1₀-FeNi with an order parameter of 0.71. The transformation of disordered-phase FeNi into the L1₀ phase increased the coercive force from 14.5 kA/m to 142 kA/m. The proposed method not only significantly accelerates the development of magnets using L1₀-FeNi but also offers a new synthesis route to obtain ordered alloys in non-equilibrium states.