Constant real-space fractal dimensionality and structure evolution in Ti62Cu38 metallic glass under high pressure

Abstract

The structure of binary $\mathrm{T}{\mathrm{i}}_{62}\mathrm{C}{\mathrm{u}}_{38}$ metallic glass is investigated under pressures up to 33.8 GPa using the pair distribution function analysis based on high-energy x-ray scattering and reverse Monte Carlo (RMC) simulations. At a global scale, its relative volume shows a continuously smooth curve as a function of pressure. The isothermal bulk modulus of $\mathrm{T}{\mathrm{i}}_{62}\mathrm{C}{\mathrm{u}}_{38}$ metallic glass is estimated as ${B}_{0}=132(3)\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$ with ${B}_{0}^{\ensuremath{'}}=5.8(0.4)$. At a local scale, the atomic packing structure under compression conditions, which is extracted from RMC simulations, shows that the topological short-range order is dominated by the deformed icosahedron polyhedra and basically maintains stable. From the relationship between the relative volume and changing ratio of the atomic separation distances, the real-space fractal dimensionality of this metallic glass is determined as about 2.5 for all of the first four peaks. This experimental result reveals the consistent nature of the fractal feature on the degree of self-similarity in this sample within the entire experimental pressure range.