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

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

JOURNAL=Frontiers in Materials

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2022.954110

DOI=10.3389/fmats.2022.954110

ISSN=2296-8016

ABSTRACT=<p>Reverse Monte Carlo (RMC) calculation was performed to visualize the atomic arrangement in a disordered Fe<sub>55</sub>Ni<sub>45</sub> 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 Fe<sub>65</sub>Ni<sub>35</sub> Invar alloy, a relationship between Fe-Fe atomic pairs, the Invar effect and elastic anomalies in the compression curve is elucidated.</p>