Model-neutron diffraction strain measurement comparisons for steady state creep of metal matrix composites

Mori and coworkers have developed a model for the prediction of the steady state creep rate of discontinuous composites based on the Eshelby model. Th is model recognizes that matrix creep can only achieve steady state creep w hen relaxation processes at the inclusion/matrix interface balance the rate of build up of internal stress. In this paper we follow through the implic ations of this model for the level of the average matrix stress attained in the steady state as a function of the applied load. We compare the predict ions with direct measurements of the matrix stress by neutron diffraction. The model indicates that the composite creep exponent should be less than t he creep exponent of the unreinforced matrix provided neither debonding nor inclusion cracking occurs. This is observed experimentally for the composi tes under the conditions studied. (C) 2000 Elsevier Science S.A. All rights reserved.