CREEP MECHANISM IN A CU-5.5-AT PERCENT AL ALLOY

The high temperature creep of a Cu-5·5 at. % Al alloy was investigated by the isothernial tests technique. Two dislocation mechanisms operating in parallel were detected. In the region of lower creep rates the apparent activation energy depends linearly on stress; to the stress σ = 0 corresponds a value close to that expected for the activation enthalpy of lattice self-diffusion of copper in the alloy. The stress dependence of minimum creep rate can be described by a power function of the σn type, where n depends both on stress and temperature. The results are in good qualitative agreement with the model of non-conservative motion of jogs on screw dislocations. In the region of higher creep rates the apparent activation energy decreases with the increasing stress and is higher than that in the lower rates region. © 1969 Taylor & Francis Group, LLC.