Microstructure of aluminium during creep at intermediate temperature—I. dislocation networks after creep

Abstract

The substructure behaviour of Aluminium has been studied at intermediate temperatures in order to determine the microscopic mechanisms which control the strain rate. This first article describes the detailed geometrical features of the dislocation networks after the creep test. The subboundaries are made of the dislocations emitted by the sources which are activated by the local stress; most of them are of mixed character, exhibiting 3 coplanar Burgers vectors at 120°; their long range stress field, if any, is smaller or equal to the creep stress; the small dislocation segments are situated in their respective glide planes, which brings some restrictions on the possible network geometries. In the subsequent articles, these features will appear as essential to understand the dynamic properties of the substructure during in situ creep experiments in a high voltage electron microscope, and to work out a new picture of creep at intermediate temperatures.