**6. Conclusion and outlook**

(shown in **Figure 11**). Three specimens were selected with average glassy grain sizes from 5 to 15 nm to investigate deformation mode transition. The deformation modes of the NGs generally transferred from localized shear banding to homogeneous plastic flow with the grain sizes decreasing, and the fine-grained even became superplastically deformed during tensile testing [49]. The effects of composition and grain size were investigated more specifically by involving Voronoi polyhedral analysis method [50]. They found that the mechanical behavior of NGs was regulated by both the grain boundary thickness and the fraction of atoms at interfaces intrinsically. The mechanical behavior of NGs had a composition dependence similar to their parent MG, while the intrinsic deformation behavior only depended on the grain size,

**Figure 10.** Local atomic shear strain distributions for MG, inhomogeneous NG and homogeneous NG at tensile of 8 and

Sha et al. constructed a sandwich architecture composed of NG and MG [51]. The constructed composite had a higher strength than pure NG, and larger plasticity than MG. The improving of plasticity was contributed by the glass-glass interfaces in NG layers and a compressive residual stress in the MG layer. They indicated a strong ductile MG could be

and not affected by the composition.

42 Metallic Glasses - Properties and Processing

16% [48].

Throughout the review, we enumerated pronounced work on the structure analysis, the connection of structure with the mechanical properties, shear bands initiation and development. With the application of structural analysis methods, the existence of SRO and MRO in MGs is confirmed. The SRO types and proportions vary with MG compositions and preparation process. Several SRO motifs with high five-fold symmetry structure, as well as their interconnected networks, are found to be great contributing factors to the solid-like characteristics of MG, which means they are closely correlated with mechanical properties and deformation patterns of MGs. The intrinsic dynamics of shear banding events were investigated from the mechanics simulations, which provided convincingly supports for the shear banding theories. Furthermore, we also demonstrated recent MD simulations works on mechanical behaviors and deformation properties of several designed nanoglass. They behaved ductile deformation ability and might be a promising derived material from casted MGs.

These works proved the atomic-level computational simulation plays a significant role in researching work of MG. However, limited by accurate potential descriptions, computational capacity and simulation methods, computational simulations of MG are still unable to build a consistent theoretical frame with experimental research both in time and space. Thus, developing effective multi-scale simulation methods and advanced experimental characterization methods is the most urgent and challenging work for the research of metallic glasses.

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