Revealing in situ stress-induced short- and medium-range atomic structure evolution in a multicomponent metallic glassy alloy

Deformation behavior of multicomponent metallic glasses are determined by the evolution of the short- and medium-range order (SRO and MRO) structures. A precise understanding of how different atom species rearrange themselves in different stress states is still a great challenge in materials science and engineering. Here, we report a systematic and synergetic research of using electron microscopy imaging, synchrotron X-ray total scattering plus empirical potential structure refinement (EPSR) modelling to study in situ the deformation of a commercial multicomponent metallic glassy alloy (Zr41.2Ti13.8Cu12.5Ni10Be22.5). Systematic and comprehensive analyses on the characteristics of the SRO and MRO structures and the decoupled 15 partial PDFs at each stress level reveal quantitatively how the SRO and MRO structures evolution in 3D space in the tensile and compressive states. The results show that the Zr-centred atom clusters have a low degree of icosahedra and are the preferred atom clusters to rearrange themselves under the tensile and compressive stresses, and the Zr-Zr pair is the dominant atom pair in controlling the initiation of shear bands and the subsequent propagation. The evolution of the MRO clusters under different stress states are realised by changing the connection modes between the Zr-centred atom clusters. The coordinated changes of both bond angles and bond lengths of the Zr-centred clusters are the dominant factors in accommodating the tensile or compressive elastic stresses. While other solute-centred MRO clusters only play a minor role in the atomic structure evolution.