The behaviour of crystalline metals and alloys is often characterized by fitting the plastic-flow part of the curve to σ f = Kεn, where ε is the strain, K is the flow stress at ε = 1.0, and the strain-hardening exponent n is typically 0.1–0.3. Considering the full range of the curve in each case, the elastic limit (circled) occurs at much higher relative stress and strain for the MG than for the conventional alloy, and n is inappropriate for characterizing the MG. Instead we use the initial rate of hardening, R = d(true stress)/d(true strain), indicated by the arrows. The MG has much higher values of R and of R/σ y —so high that, except in close-up (for example, Fig. 1b inset), the transition from elastic to plastic deformation is difficult to discern—and a much smaller total increase in flow stress σ f relative to σ y . The high value of R/σ y leads to rapid saturation of the hardening, after which the MG reverts to the strain-softening behaviour of as-cast unrejuvenated glasses. Notably, however, the rejuvenated and then hardened glass continues to have much more uniform flow (smaller stress serrations) than an as-cast glass. The curve for the stainless steel is based on published data43, and can be taken as an intermediate case for engineering alloys: the value of R/σ y and the strain to failure is higher for pure metals and lower for hardened alloys. The curve for the MG measured in this work was obtained on continuous loading under compression.