High-Temperature Creep of Fibrous Metal-Matrix Composites under Varying Stresses

The present paper is aimed at testing the hypothesis about the failure of the relatively weak fiber/matrix interface under cyclic loading, which causes an increase in the steady-state creep rate. The hypothesis is tested qualitatively by comparing the creep behavior of composite specimens with various interface strengths under the conditions mentioned (loading-unloading-loading to the original level). The hypothesis is tested semi-quantitatively by estimating the interface strength in relation to the action decreasing the strength. The latter requires the use of a microstructural calculation model. Both the approaches are used in the paper, and the results found support this hypothesis. The experimental data obtained are an additional argument for the necessity of developing metal-matrix composites with a strong interface, which can be a basis for real creep-resistant high-temperature composites.