**4. Summary and Conclusions**

The results presented in this study testify to the existence and significance of Volterra dislocation-type long-range elastic strain/stress fields around a shear band tip in deformed BMGs. Such a stress field a ffects the behaviour of the SB under external load and can be revealed by examining the surrounding surface topography. In order to study the SB's topological features, 3D surface scanning of the deformed BMGs was conducted with aid from the SWLI technique. Di fferent stress conditions were achieved in BMGs under mechanical compression and indentation testing to stimulate di fferent shear modes and SB's interactions. The results of the 3D surface mapping of the deformation-induced shear zones were analysed by taking into account the existence of long-range strain/stress field around each SB tip. The results can be summarised as follows.

(1) The elastic field around a tip of the SB in a BMG was experimentally approved to be similar to the elastic field of the Volterra-type macro-dislocation, revealing edge-like (mode II shear) and screw-like (mode III shear) shear components. Thus, SBs in BMGs can be described in terms of the Volterra's macro-dislocations and their behaviour under load can be rationalised accordingly.

(2) The long-range stress fields produced by macro-dislocations are supposed to be responsible for the frequently reported SB-SB interactions causing branching, deflecting, mutual blocking, and local strain hardening.

(3) The o ffset of a mode II shear under uniform compression coincides with the shear propagation direction. This determines the SB's path and o ffsets deviations, which gives rise to the mode II shear features including the progression of a solitary shear band along the straight path without significant deviations, and a monotonic o ffset change from the tip to the specimen edge without significant offset deviations.

(4) The o ffset of the mode III shear under uniform compression is perpendicular to the shear propagation direction. Having no strong constraints on the path or o ffset, the mode III shear tend to curve exhibiting significant deviations of the path and in the o ffset. This mode of SBs shows a segmented morphology, where each segmen<sup>t</sup> represents a separate mode III shear, which bends away from the primary shear plane toward the side by forming a sort of a "dislocation-like" wall.

(5) The SWLI technique applied to compressed BMG specimens reveals local deviations both in the shear path and shear step height in qualitative agreemen<sup>t</sup> with suggestions by Gilman [49] and Binkowksi et al. [17]. The shear offset deviations were found to accumulate with every following shear event. Shear deviation accumulation is believed to be the main reason for the crack initiation and failure of BMGs.

(6) The behaviour of SBs in deformed BMGs is strongly affected by their self-induced local strain/stress fields leading to frequently observed and, reported in the literature, SB interactions revealed as branching, rejuvenation, mutual blocking, and deflection of propagating SBs.

**Author Contributions:** Conceptualization, methodology, software, validation, analysis, investigation, visualization, writing, original draft preparation—M.S. Writing—review and editing, supervision, project administration—A.V. Both authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** The authors gratefully acknowledge the Institute of Advanced Technologies of Togliatti State University, Russia, and, particularly, Dmitriy L. Merson for granting access to the experimental equipment. The authors also would like to thank the Institute of materials physics of the University of Münster, particularly, the group of Gerhard Wilde and Sergiy V. Divinski for the provision of materials and manufacturing facility for the fabrication of Pd-based metallic glasses.

**Conflicts of Interest:** The authors declare no conflict of interest.
