On plastically-accomodated creep in an inclusion bearing material

The creep behavior in a discontinuous fiber-reinforced metal–matrix composite without other interfacial relaxation mechanisms than matrix plastic flow has been examined. The existence of steady-state creep is revealed from the following four points; First, it is pointed out that the variation principles do not prove the existence of the energy minimum state and the creep termination. Second, it is shown that for viscous matrix material, creep continues with the same strain as elastic, which is important and does not change the stress distribution. Third, finite element method (FEM) analysis reveals steady-state creep. Without the constant dilation option, an incorrect result of the creep termination is obtained. At last, the creep behavior of Al–Al3Ni in situ composite is measured experimentally. At high stresses, a stress exponent of 5 and an activation energy of 130 kJ mol−1 are obtained, showing plastic accomodation, while at low stresses, 1 and 85 kJ mol−1 are obtained showing diffusional accomodation.