| A mechanical spectroscopy study has been made on fine-grained Ni-TZP(ZrO₂-3 ㏖.%Y₂O₃) composite in an attempt to assess the following micromechanical prediction. A dual-phase material with fine-grained constituents deforming by Coble-type boundary-diffusion creep exhibits viscoelastic (anelastic plus viscous) behavior. A composite with 10 vol.%TZP, fabricated by powder processing is examined. Dynamic Young`s modules, E_ω and internal friction, tan Φ, are measured over a temperature range of 25 to 800℃ at frequencies of 0.01, 0,05 and 0.1 Hz using a specially designed tension-compression apparatus. The data obtained are analyzed in terms of loss compliance, J₂◎ tanΦ/E_ω. Two relaxation peaks are observed in the composite. An exponential involved in the peak and background components are determined and, by making a further analysis based on the micromechanical formulation and also taking the well-known relaxation due to viscous grain-boundary sliding into account, the implications of these quantities are discussed in terms of constituent material parameters(boundary diffusivity, grain size. etc.). |
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