1989 Volume 53 Issue 1 Pages 50-57
Creep tests and high temperature tensile tests were carried out on the coarse-grained dispersion-hardened Al-Al2O3-Zr alloy which had an anisotropy of strength due to the recrystallization texture. There types of specimens were used for the tests, each of which had a specimen axis orientation of 0, 45 or 90 degrees against the rolling direction, respectively. Relations between the critical stress for creep deformation and the proof stress were examined.
The existence of critical stress for creep deformation, σc, was recognized at temperatures from 573 to 773 K. The specimens of 0° orientation had the highest critical stress and creep strength, and the specimens of 90° orientation had the lowest ones. It was shown that the creep deformation could be explained as being controlled by the self-diffusion of Al when it was taken into account that σc decreases with the rise of temperature. The temperature dependence of σc was thought to be due to the interaction between dislocations and impurity atoms which segregated on the interface between dispersed particles and the matrix. Ratios of σc to the 0.1 and 0.01% proof stresses at room temperature, which were thought to be a criterion of the Orowan stress, were in the range from 0.5 to 0.8. Each ratio was nearly constant at the same temperature independent of the axis orientation. The ratio decreased gradually with the rise of temperature, which showed that the interaction between the dislocations and the dispersed particles changes with the rise of temperature.
