Fig. 6: Deformation mechanism map and material properties revealed by nanomolding.

a Viscosity (red) and interface diffusivity (1/D_I, blue) calculated according to η\(=\frac{{pt}}{32}{(\frac{d}{L})}^{2}\) and D_I\(=\frac{{L}^{2}}{{pt}}\frac{d{k}_{B}T}{8\varOmega \delta }\) for each temperature based on the experimental data in Fig. 5. A kink in the measured viscosity data at T_g – 30 °C indicates the bulk glass transition under conditions used here for the nanomolding. The viscosity data of the metastable equilibrium state (supercooled liquid) is fitted with VFT equation, and for the glass state with an Arrhenius behavior. The interface diffusivity data are fitted with an Arrhenius behavior (solid blue line). For temperatures below T_g – 30 °C (η ~ 10¹² Pa·s) the calculated viscosity no longer follows the VFT prediction, thereby inducing a non-monotonic behavior of the critical length scale, d_c. Source data are provided as a Source Data file. b Deformation mechanism map for nano-scale Ni-BMG based on the fitted viscosity and diffusivity shown in a. The circles mark the d_c measured from scaling experiments in Fig. 5. At even larger length scales than the here discussed collective to individual atomic transport transition, shear localization dominates the deformation at low temperatures when the experimental time scale exceeds the intrinsic relaxation time scale of the BMG. Source data are provided as a Source Data file. c Using the measured viscosity and interface diffusivity data, we calculated the bulk diffusivity of the Ni-BMG and revealed a breakdown of Stokes-Einstein relation (SER) at ~ 1.15 T_g. d Bulk and interface glass transition temperatures differ due to their different internal time scales^{27, 30}. Considering the here used external time scales and using the experimentally determined bulk and interface relaxation times, the interface glass transition (with experimental time scale t_molding = 36,000 s) occurs at ~ 254 °C and the bulk glass transition at ~ 288 °C.