Internal stress and defect-related free volume in submicrocrystalline Ni studied by neutron diffraction and difference dilatometry

A combined study of neutron diffraction and difference dilatometry
on submicrocrystalline Ni prepared by high pressure torsion aims
at studying the anisotropic behaviour during dilatometry and its
relation to internal stress and structural anisotropy. Macroscopic
stresses were undetectable in the dilatometer samples. Along with
specific tests such as post cold-rolling, this shows that an observed
anisotropic length change upon annealing is not caused by internal
stress, but can be explained by the inherent microstructure, i.e. the
anisotropic annealing of relaxed vacancies at grain boundaries of
shape-anisotropic crystallites.