  Theoretical predictions of the ideal strength of materials range from E/30 to
E/10 (E is Young's modulus). However, despite intense interest over the last
decade, the value of the ideal strength that can be attained experimentally for
metals remains a mystery (1-5). In this study, we demonstrated the
unprecedented strength of an amorphous Cu-Zr alloy that surpassed the E/10
limit. Laser-induced shock experiments were conducted on Cu50Zr50 to explore
its strength and failure mechanisms at ultrahigh strain rates. The material
demonstrated a high spall strength of 9.8 GPa, approximately 1/13 of its P-wave
modulus (~ E/6), at strain rates greater than 10^7 s^-1, which sets a new
record for the elastic limit of metallic materials. Electron microscopy and
large-scale molecular dynamics simulations revealed that void nucleation and
growth, not shear-banding, comprised the major failure mechanism for metallic
glasses at extremely fast strain rates. A new model for void formation under
the control of surface energy explained the rate dependence of the material
strength. The results of this study reveal new possible ways to use the
amorphous phase in nanostructured metals in future applications under demanding
mechanical conditions.
