Elastostatic loading of metallic glass-crystal nanocomposites: Relationship of creep rate and interface energy

We study the creep behavior of Cu₆₄Zr₃₆ glass-crystal nanocomposites under elastostatic loading conditions in molecular dynamics simulations. By manipulating the glass-crystal interfaces of a precipitation-annealed glass containing Laves-type crystallites, we show that the creep behavior can be tuned. Specifically, we find that for the same microstructure the creep rate scales exponentially with the excess energy in the interfaces, which we raise artificially by disturbing the local short-range order in the atomistic model. The behavior shows analogies to Coble creep in crystalline metals, which depends on grain boundary diffusivity and implicitly on grain boundary energies.