Dynamic Evolution of Local Atomic Environments in a Cu[sub.66]Zr[sub.34] Bulk Metallic Glass

• Published in: Metals (Basel ) Vol. 14; no. 10
• Main Authors: Pereira, Luan de Moraes, Tercini, Marcela Bergamaschi, Zúñiga, Alejandro, Veiga, Roberto Gomes de Aguiar
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.10.2024
• Subjects: Analysis; Metallic glasses; Molecular dynamics; Marshall Islands
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met14101139

This study presents a molecular dynamics (MD) investigation of the evolution of local atomic environments (LAEs) in a Cu[sub.66]Zr[sub.34] bulk metallic glass (BMG), both at rest and under constant shear deformation. LAEs were characterized using Voronoi polyhedra analysis. Even in the absence of external load, LAEs frequently transformed into one another due to short-ranged atomic position fluctuations. However, as expected, each transition from one polyhedra to another was balanced by the reverse transition, thereby preserving the proportions of the different polyhedra. Cu-centered icosahedral LAEs were observed to preferentially transform into and from <1,0,9,3,0>, <0,1,10,2,0>, and <0,2,8,2,0> LAEs. Upon applying pure shear, the simulation box was first deformed in one direction up to a strain of 25% and then in the opposite direction to the same strain level. Shear deformation induced large nonaffine atomic displacements in the directions parallel to the shear, which were concentrated in specific regions of the BMG, forming band-like regions. From the onset, shear deformation led to the destabilization of Cu-centered icosahedral LAEs, as indicated by more frequent transitions to and from other polyhedra. Unlike other Cu-centered LAEs, icosahedra were also found to be more sensitive to yielding. The destruction of Cu-centered icosahedra was primarily a result of net transformations into <1,0,9,3,0> and <0,2,8,2,0> LAEs in the BMG subjected to pure shear, with a minor contribution of transformations involving the <0,1,10,2,0> polyhedra.