Effect of mutual substitution of Fe and Ni elements on the plasticity of Fe/Ni-based amorphous alloys: Ab initio molecular dynamics simulations

Abstract In order to study the effect of the mutual substitution of Fe and Ni on the plasticity of Fe/Ni-based metallic glasses (MGs) from the atomic arrangement structure perspective, we investigate the short-range order (SRO) and medium-range order (MRO) structures of Fe 80 P 14 B 6 , Fe 40 Ni 40 P 14 B 6 and Ni 80 P 14 B 6 MGs using ab initio molecular dynamics (AIMD) simulations method. The results reveal that Fe 40 Ni 40 P 14 B 6 MG has more vertex-sharing clusters and less edge-sharing clusters compared to Fe 80 P 14 B 6 and Ni 80 P 14 B 6 MGs, indicating that Fe 40 Ni 40 P 14 B 6 MG possesses more cavities or boundaries on MRO, which are beneficial for plastic deformation. In addition, large clusters have a relatively strong connection with comparatively smaller clusters in Fe 80 P 14 B 6 and Ni 80 P 14 B 6 MGs while the clusters with the similar size tend to form the nearest neighbor in Fe 40 Ni 40 P 14 B 6 MG. Compared with the former, the connection mode of the latter may form relatively loose packing, which can facilitate plastic deformation. Fe 40 Ni 40 P 14 B 6 MG has larger population of 142×, 1441 and 1661 bond pairs, which are crystal-like clusters, and relatively smaller 1551and 1541. Besides, Fe 40 Ni 40 P 14 B 6 MG has less , and clusters and more and compared to Fe 80 P 14 B 6 and Ni 80 P 14 B 6 MGs, indicating the replacement of Fe by Ni or Ni by Fe in Fe/Ni-based MGs reduces five-fold rotational symmetry, which is beneficial to plasticity.