  Difference dilatometry and differential scanning calorimetry (DSC) are used
to investigate defect annealing in ultrafine grained nickel processed by equal
channel angular pressing (ECAP) at various temperatures. Different defect types
and processes such as vacancies, dislocations, grain boundaries and
grain-boundary relaxation can be detected. They can be distinguished due to
their distinct kinetics as revealed by the release of excess volume and excess
heat during linear heating. The data are quantified in combination with a
detailed characterization of the microstructure. Values for the absolute
vacancy concentration, the dislocation density, the grain boundary expansion
and the excess of grain boundary expansion in ECAP-processed nickel are
derived.
