A promising remedy to the failure of metallic glasses (MGs) by shear banding is the use of a dense network of glass-glass interfaces, i.e., a nanoglass (NG). Here we investigate the effect of grain size (d) on the failure of NG by performing molecular dynamics simulations of tensile-loading on Cu₅₀Zr₅₀ NG with d = 5 to 15 nm. Our results reveal a drastic change in deformation mode from a single shear band (d ∼ 15 to 10 nm), to cooperative shear failure (d ∼ 10 to 5 nm), to homogeneous superplastic flow (d ≤ 5 nm). Our results suggest that grain size can be an effective design parameter to tune the mechanical properties of MGs.

Metallic glasses (MGs) are often perceived as quintessential structural materials due to their superior mechanical properties such as high strength and large elastic limit. In practical applications, service conditions that introduce cyclic variations in stresses and strains are inevitably involved. The fatigue of MGs is thus a topic of research and practical interest. In this review, a brief introduction on MGs, their applications and challenges, is first provided. Next, experimental studies on fatigue behaviors of both macroscopic and nanoscale MGs are summarized. The range of topics covered include the stress-life behavior, fatigue-crack growth behavior, fatigue-fracture morphology, fatigue-failure mechanisms, as well as the effects of chemical composition, cycling frequency, loading condition, and sample size on the fatigue limits. Finally, recent progresses in simulation studies on the fatigue of MGs are discussed, with an emphasis placed on the atomic-level understanding of the fatigue mechanisms.

Aside from ultrahigh strength and elasticity, metallic glasses (MGs) possess a number of favorable properties. However, their lack of dislocation based plastic deformation mechanisms in crystalline metals and the resulting loss of ductility have restricted the engineering applications of MGs over the last 60 years. This review aims to provide an overview of deformation and failure mechanisms of MGs via formation and propagation of shear bands (SBs), with an emphasis on the control of SBs to promote strength-ductility synergy. With this goal in mind, we highlight some of the emerging strategies to improve the ductility of MGs. Topics covered include postprocessing techniques such as precompression, heterogeneity tuning, and rejuvenation, with a primary focus on recent progresses in structural design based methods including nanoglasses, notched MGs, and MG nanolattices, as future innovations toward strength-ductility synergy beyond the current benchmark ranges.

Cellular metallic glasses (MGs) can be good candidates for structural and functional applications due to their light weight, enhanced ductility and excellent energy absorption performance.

Although minor alloying in metallic glasses (MGs) has been extensively investigated, the effect of O doping is still a debatable topic. In the present study, the atomic-level structures and mechanical properties of Zr-based MGs doped with different O contents have been analyzed using ab initio molecular dynamics simulations. It is revealed that O atoms prefer to bond to Zr atoms due to their low mixing enthalpy, and that O atoms degrade the properties of Zr-lean MGs but hardly affect the properties of Zr-rich MGs, with results suggesting a compositional dependence of O doping. For Zr-lean MGs, the fraction of full icosahedra, size of the medium-range-order clusters, Young's modulus and shear modulus decrease sharply with O content, while accompanied by a sharp increase of the non-Frank–Kasper polyhedra, and the ratio of bulk modulus to shear modulus and Poisson's ratio, indicating decreased strength and improved plasticity. For Zr-rich MGs, however, the above-mentioned structural and mechanical features experience little change or only change slightly after O doping, showing low oxygen sensitivity. It is shown that the high Zr content weakens the effect of Zr–O bonding to some extent. The present study not only sheds light on the atomic-level structures of O-doped MGs, which may provide guidelines for designing MGs with low-grade materials, but also helps to explain the previous conflicting results based on the composition-dependence effect.