Creep behaviour of icosahedral Al-Cu-Fe

Transient creep experiments have been performed on poly-quasicrystalline specimens of the icosahedral Al-Cu-Fe phase. Three temperatures (870, 960 and 1000 K) have been selected in the ductile regime for creep stresses that range between 30 and 320 MPa. In these experiments, the specimens are first loaded in constant strain-rare conditions, then the testing machine is switched to load control and the specimens are allowed to deform under creep conditions. One- or two-stage creep curves have been obtained depending on temperature, stress and on the deformation level of the stress-strain curve at which the creep tests were performed. When creep conditions are applied before the upper yield stress, at low stress, only a stage of continuous decrease in creep rate is observed, while at higher stress this primary stage is followed by a stage of accelerated creep rate. These two-stage creep curves are predicted within the framework of the strain dependent friction stress model. For creep tests beyond the upper yield stress, only the stage of accelerated creep rate is observed. No distinct steady-state stage has been observed for all investigated creep conditions. (C) 2000 Elsevier Science B.V. All rights reserved.