Modeling and measurements of creep deformation in a ceramic fiber reinforced metal matrix composite

Abstract

This study proposes a novel analytical model for creep deformation in long brittle fiber-reinforced metal matrix composites. Unlike traditional creep models based on the steady-state creep expression of the creep behavior for the matrix in the composite, this model addresses the unsteady-state creep behavior. It also highlights the similarity between the governing equations for creep testing of the composite and stress relaxation testing of the unreinforced matrix. Owing to load transfer from the creeping matrix to the rigid fiber during the creep process, the matrix experiences decreasing stress and theoretically never reaches a steady state. Creep tests are conducted on a SiC fiber-reinforced Ti–6Al–2Sn–4Zr–2Mo-0.1Si alloy composite, within a stress range of 1100∼1350 MPa at 500 °C, with strain variation measured by an extensometer. Experimental results reveal significant discrepancies between the observed data and predictions based on steady-state creep assumptions. The differences between previous models and the proposed model are discussed using the experimental data.