Abstract
The effect of stress and temperature on the steady state creep rate of SiCw/2124 Al (T4) has been determined. The stress exponent for steady state creep of the composite is shown to increase from a value of 8.4 at 177 °C to a value of 21 at 288 °C. The activation energy for creep was determined to be 277 kJ/mol for testing in the temperature range from 149 to 204 °C and 431 kJ/mol for testing from 274 to 302 °C. These values are much greater than that for self-diffusion in aluminum. Such a severe temperature and stress dependence of the steady state creep rate is characteristic of precipitation and oxide dispersion strengthened nickel-base superalloys, where the creep behavior is explained by the particle strengthening contribution being a significant fraction of the applied creep stress. In contrast, the estimated particle strengthening for the composite is much less than the applied creep stresses. Alternate strengthening mechanisms are proposed to account for the observed creep behavior of the composite material, including the effect of temperature on the measured values of the stress exponent and activation energy for creep.
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