  Nickel carbon nanotube composites with varying amounts of carbon nanotubes
are deformed by high pressure torsion at different deformation temperatures to
high strains, where no further refinement of the Nickel matrix microstructure
is observed. Mean Nickel grain sizes increase with increasing HPT deformation
temperature, while the size of the carbon nanotube agglomerates is
significantly reduced. Additionally, the distribution of the agglomerates in
the metal matrix becomes more homogenous. To investigate the mechanical
performance of the HPT deformed composites, uniaxial tensile and compression
tests are conducted. Depending on the HPT deformation temperature and the
resulting microstructure, either brittle or ductile fracture occurs. Increased
HPT deformation temperatures induce a decrease in the anisotropy of the
mechanical properties, mainly caused by a shrinking of the carbon nanotube
agglomerates. It is shown, that tuning the HPT deformation temperature is the
key for optimizing both the microstructure and the mechanical performance.
