TEMPERATURE-DEPENDENT YOUNGS MODULUS OF AN SICW/AL2O3 COMPOSITE

摘要

Using a computer-controlled resonant-bar apparatus at frequencies near 5 kHz, we determined the temperature-dependent (86-732 K) Young's modulus of a ceramic-ceramic composite with a 0.30 volume fraction of SIC whiskers in an Al2O3 matrix. Using a megahertz-frequency pulse-echo method, it was verified that the composite shows little anisotropy (variation of the elastic properties with direction). Using a scattered-plane-wave ensemble-average method, we modelled the ambient-temperature elastic constants and found good model-observation agreement. To model the behaviour of the Young's modulus with temperature, Varshni's three-parameter relationship for Einstein-oscillator monocrystals was used. Again, good model-observation agreement was found. The mechanical-loss spectrum showed no remarkable features, indicating good whisker-matrix interface properties up to 732 K. [References: 12]