**2. Materials and Methods**

Pd-based and Zr-based BMG ingots were produced by a suction casting process in a copper mould under a purified argon atmosphere. Processing details are given in Reference [35] for Pd40Ni40P20, Reference [36] for Zr48Cu45Al7, and Reference [37] for Pd40Cu30Ni10P20, respectively. All specimens for mechanical testing were shaped by spark erosion. The samples with 2 × 2 × 4 mm<sup>3</sup> dimensions were prepared from the Pd40Ni40P20 (PdNiP) glassy ingot. The surfaces were polished to a mirror finish for shear band observations at di fferent scales. The samples of Pd40Cu30Ni10P20 (PdCuNiP) were shaped to 2.66 × 2.66 × 5.5 mm<sup>3</sup> dimensions. U-shaped and square notches were introduced in these samples to localise the deformation zone and provoke the SB nucleation in the field of view of the camera used for in-situ imaging of the deformation surface and the digital image correlation (DIC) analysis. One batch of the samples was polished to the mirror finish for SB observations and the SWLI analysis of the shear band profiles. The other batch was kept in the as-cast state for the measurement of displacement fields around SB tips with the help of DIC analysis.

Compression experiments were carried out using the rigid mechanical testing system comprising of a screw-driven tension/compression module Kammrath and Weiss (Kammrath and Weiss, Dusseldorf, Germany), high-speed video camera Photron SA3 (Photron Ltd, Tokio, Japan) and the acoustic emission triggering circuit designed to interrupt the experiment when a new SB emerges. Details of the experimental setup have been documented in Reference [38]. Samples were loaded in compression between two parallel lubricated tungsten carbide plates with a speed of 1 μm/s. When the new SB appeared at the free surface, the testing system was stopped automatically, the samples were unloaded, and the surface topology was investigated by SWLI (Zygo NewView 7100, Zygo Corporation, Middlefield, CT, USA).

A piece of the as-cast Zr48Cu45Al7 (ZrCuAl) alloy was polished to a mirror finish for micro-indentation experiments performed using the Nanovea Scratch tester (Nanovea, Irvine, CA, USA) at 20 N force applied to the diamond Berkovich indenter (three-sided pyramid) with the loading/unloading speed of 1 N/s and the load holding time of 10 s. The shear bands emerging around the indenter were observed using the SWLI technique. To reveal the possible interactions between the SBs, the indentations were performed close to each other, of 50 μm apart, so that the indenter a ffected deformation zones overlapped. After indentation, the sample surface was scanned by SWLI.
