2. Creep mechanisms. Effect of material microstructure

2.1 Low-temperature mechanisms

At low temperatures (T < 0.4 to 0.5 T _f ), plastic deformation occurs, linked to dislocation mechanisms.

During loading and primary creep, dislocations are created and propagate. In general, these dislocations do not form specific cellular structures, but are rather entangled. The structures formed by dislocation sliding can be observed: deformation bands and sliding lines spaced at varying distances depending on the applied stress and creep time.

During secondary creep, the dislocations assemble to form a more or less clear-cut cell structure: this corresponds to polygonization of the slip. The cell walls are made up of entangled dislocations (figure...