Creep deformation of an aluminium alloy with intermetallic particles

Abstract

An aluminium alloy containing different types of intermetallic particle has been used to study the creep process at temperatures ranging between 0.5 T _M and 0.56 T _M. The creep parameters obtained, namely the strain rate dependence on stress and the activation energy, have been analysed in terms of the deformed microstructures observed. The existence of different types of ordered particle leads to different dislocation-particle interactions occurring at a given time. Peripheral dislocations are observed at the particle's interfaces in some cases, while other particles appear to be cut by dislocations. Analysis of the high apparent activation energy obtained (300 kJ mol-¹), independent of stress and temperature, has shown that this term contains both a thermal and a mechanical contribution. Interpretation of the creep process occurring at these temperatures has been made in terms of the fact that the stress concentrations occurring at the particle's interfaces help dislocation detachment by a thermally activated process.