Atomic packing and medium-range order in Ni3Al metallic glass

S Trady and A Hasnaoui and M Mazroui, JOURNAL OF NON-CRYSTALLINE SOLIDS, 468, 27-33 (2017).

DOI: 10.1016/j.jnoncrysol.2017.04.026

In this report, classic molecular dynamics simulations based on the embedded atom method (EAM) are carried out to study the atomic arrangement in Ni3Al metallic glass. The short-range order (SRO) and medium-range order (MRO) in the rapidly quenched Ni3Al alloy are characterized by the both structural analysis methods; Radial distribution function (RDF) and Voronoi tessellation. From RDF, we found a splitting in the second peak that reflects the atomic packing beyond the nearest neighbors and it is a characteristic of the MRO. Furthermore, the transition from the supercooled state to the glassy state of Ni3Al alloy leads to an increased population of icosahedral- like clusters and their spatial connectivity via vertex-sharing (VS), edge-sharing (ES), face-sharing (FS) and intercross-sharing (IS). Interestingly, by comparing the position ratios of subpeaks in RDF with those of the shared cluster distance to the first peak in RDF, we suggest that the first subpeak originates from the face sharing clusters while the second one results from the vertex-sharing clusters. However, the edge-sharing is hidden between the two subpeaks due to its smaller fraction in the system.

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