Effect of temperature and strain rate on deformation behavior in metallic glassy films

Both the effects of temperature and strain rate on the deformation behavior of metallic glass thin films (Ni60Nb40, Cu44Zr44Al12 and Zr55Cu15Ni13Al17) were systematically investigated. The evolution of surface morphology of magnetron sputtered thin films co-bent with the Ti substrate was monitored. A transition from highly localized deformation to non-localized deformation was observed at various temperatures and strain rates by reducing the film thickness to a critical thickness, which can be understood on the basis of Young's modulus, Poisson's ratio, Griffith's crack-propagation criterion and elastic energy transferring efficiency of the material. Temperature and strain rate dependence of the critical thickness for transition are discussed to shed light on the deformation mechanism of glassy thin films.