Bond length deviation in CuZr metallic glasses

Abstract

We define a structural parameter, called atomic bond length deviation ($\mathrm{BL}{\mathrm{D}}_{\mathrm{i}}$), to characterize structural heterogeneity of CuZr melt and metallic glass (MG). Molecular dynamics simulations have been performed to explore the average $\mathrm{BL}{\mathrm{D}}_{\mathrm{i}}$ of the system evolution with temperature during $\mathrm{C}{\mathrm{u}}_{64}\mathrm{Z}{\mathrm{r}}_{36}$ and $\mathrm{C}{\mathrm{u}}_{50}\mathrm{Z}{\mathrm{r}}_{50}$ MGs formation and the correlation between $\mathrm{BL}{\mathrm{D}}_{\mathrm{i}}$ and thermal relaxation/local atomic shear strain upon compressive loading. The results indicate that $\mathrm{BL}{\mathrm{D}}_{\mathrm{i}}$ contains both symmetrical characteristic and volumetric information of the short-range order clusters while symmetry seems to play a more important role in relaxation and deformation events; the fast decreasing of average $\mathrm{BL}{\mathrm{D}}_{\mathrm{i}}$ near above the glass transition temperature ${T}_{\mathrm{g}}$ with decreasing temperature corresponds to the sharp increase of the number of full icosahedra while the shear transformation zones or single jump events have a high propensity to originate from those regions with the higher $\mathrm{BL}{\mathrm{D}}_{\mathrm{i}}$ clusters. Additionally, the system average $\mathrm{BL}{\mathrm{D}}_{\mathrm{i}}$ can also be accessed experimentally, through the radial distribution function.