Supermodulus effect by grain-boundary wetting in nanostructured multilayers

Abstract The effect of thermal treatments on mechanical properties was systematically investigated in Ni/Mo multilayers with a constant modulation period (160 nm) prepared by magnetron sputtering deposition. A supermodulus effect was found in the annealed multilayers as compared to the as-deposited state. A large tensile stress development was observed in the multilayers. The evolution of grain-boundary (GB) wetting was observed at the interfaces of the multilayers, which results in an enhanced modulus based on the mechanism of GB-wetting-induced interfacial stress/strain. The GB wetting phenomenon was further supported by a thermodynamic calculation. The results not only bring clear evidence of the important role of interfacial structures in governing the elastic behavior of metallic multilayers, but also allow designing the multilayers with special properties through atomic diffusion and wetting at the interfaces based on the thermodynamic calculation.