Beschreibung:
<jats:p>Severe plastic deformation, SPD, enables the grain refinement of bulk materials.
However, at strains larger than a critical value, no further microstructural refinement can be
observed. This regime is denoted as saturation region of the microstructural size. It will be shown
that this regime can be divided into a thermal and an athermal part. The transition between these
two regimes was examined in an Al-3wt.%Mg alloy. The single phase alloy was deformed by high
pressure torsion (HPT) at various temperatures and different rotational speeds. During the HPTdeformation
the flow stress was measured by a torque cell in a temperature range between -196°C
(evaporation temperature of the liquid nitrogen) and 450°C. The temperature and the strain rate
dependent behavior reveal a shift of the onset of the thermal activated regime towards higher
temperatures by an increase of the strain rate.</jats:p>