High temperature stress relaxation in Ti- and Cu-doped reaction bonded Al2O3

The high temperature plastic behavior of reaction-bonded alumina doped with copper and titanium oxide has been studied by means of stress relaxation tests in air providing the strain rate vs. stress curves at fixed temperature in a very straightforward way. The experimental data have been correlated with the microstructural observations and X-ray diffraction to deduce the deformation mechanism. The material shows plastic behavior at temperatures above 950 °C. Around 1000 °C, a linear plastic deformation law has been observed and both below and above this temperature the stress exponent takes higher values.