Frontiers in Materials (Sep 2022)

Visualization of the disordered structure of Fe-Ni Invar alloys by reverse monte carlo calculations

  • Yusuke Kubo,
  • Naoki Ishimatsu,
  • Naoto Kitamura,
  • Naomi Kawamura,
  • Sho Kakizawa,
  • Masaichiro Mizumaki,
  • Ryuichi Nomura,
  • Tetsuo Irifune,
  • Hitoshi Sumiya

DOI
https://doi.org/10.3389/fmats.2022.954110
Journal volume & issue
Vol. 9

Abstract

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Reverse Monte Carlo (RMC) calculation was performed to visualize the atomic arrangement in a disordered Fe55Ni45 alloy, which is classified as an intermediate structure between the non-crystalline glass and crystalline structures. The optimized structure of the ferromagnetic phase at low pressures revealed that Fe and Ni atoms were displaced from a perfect fcc lattice to elongate the nearest neighboring Fe-Fe atomic pairs, therefore, Fe-Fe atomic pairs have longer bond length than Fe-Ni and Ni-Ni atomic pairs. Because the elongation becomes negligible during the pressure-induced destabilization of the ferromagnetic state, the elongation of Fe-Fe pairs is the atomic scale origin of the volume expansion due to a large magnetovolume effect. Compared with the atomic arrangement in the Fe65Ni35 Invar alloy, a relationship between Fe-Fe atomic pairs, the Invar effect and elastic anomalies in the compression curve is elucidated.

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