Shear modulus of coevaporatedNi1−xZrxthin films

Electron-beam evaporation was used to deposit ${\mathrm{Ni}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Zr}}_{\mathit{x}}$ alloy thin films, 0<x<1.0, onto piezoelectric quartz-crystal substrates. For 0.1<x<0.87, the films are single-phase amorphous. Surface acoustic (Rayleigh) waves were generated and detected on the substrates using interdigital transducers predeposited on the substrate surface. The difference between the Rayleigh wave velocity before and after the deposition of the ${\mathrm{Ni}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Zr}}_{\mathit{x}}$ films is used to deduce the shear modulus, μ(x), of the films through a first-order perturbation theory. For all compositions, μ(x) is lower than the weighted average of the μ values of the pure Ni and Zr films. Within the range 0.1<x<0.87, μ(x) has five narrow maxima indicative of chemical short-range ordering at selected compositions.