DETERMINATION OF THE INTERFACIAL-TENSION BY ZERO CREEP EXPERIMENTS ON MULTILAYERS .2. EXPERIMENT

Tensile creep tests were conducted between 700 and 800-degrees-C on free-standing silver-nickel multilayered thin films with individual layer thicknesses between 0.5 and 1.3 mum. At different loads, both negative and positive strain rates were measured, from which the zero creep load was determined by interpolation. The zero creep load was found to be proportional to the number of bilayers in the film. The interfacial tension was obtained from the zero creep load per bilayer using a newly developed kinetic model for Coble creep in a multilayer [D. Josell and F. Spaepen, Acia metall. mater. 41, 3007 (1993)]. The correction factors in the model involve the aspect ratio of the grains (determined directly by electron microscopy) and the ratios of the interfacial tension to the grain boundary tensions (determined from the groove angles in the electron micrographs). The tension of the silver-nickel (111) epitaxial interface was found to be 0.76 +/- 0.12 J/m2.