Pressure-induced local structural crossover in a high-entropy metallic glass

Abstract

Achieving effective tuning of glass structures between distinct states is intriguing for fundamental studies and applications, but has previously turned out to be challenging in practice. High-entropy metallic glasses (HEMGs), as an emerging type of metallic glasses (MGs) based on the high-entropy effect, are expected to have more disordered and frustrated chemical short-range structure compared with conventional MGs. Therefore, HEMGs may offer possibilities for structure and properties tuning in glasses. In this work, we employ pressure as a tuning parameter and monitor the atomic structural evolution of a senary HEMG, ${\mathrm{Ti}}_{16.7}{\mathrm{Zr}}_{16.7}{\mathrm{Hf}}_{16.7}{\mathrm{Cu}}_{16.7}{\mathrm{Ni}}_{16.7}{\mathrm{Be}}_{16.7}$, up to \ensuremath{\sim}40 GPa using in situ synchrotron x-ray diffraction. Analysis of its structure factor in reciprocal space and reduced pair distribution function in real space both reveal a pressure-induced structural crossover at \ensuremath{\sim}20 GPa with a dramatic change in short-range order (SRO), while no similar phenomenon is observed in a conventional MG, ${\mathrm{Cu}}_{36}{\mathrm{Zr}}_{64}$, as a control sample, suggesting the pressure-induced highly tunable SRO in HEMGs originates from the local chemical complexity, namely, the high-entropy effect. These results confirm that enhanced flexibility and tunability of atomic structures could be achieved by introducing the high-entropy effect into MGs. Therefore, configurational entropy could be another dimension for exploring MGs with highly tunable structures and properties for various potential applications.