Effect of high-pressure torsion processing on the microstructure evolution and mechanical properties of consolidated micro size Cu and Cu-SiC powders

In this paper, micro size Cu and Cu-SiC composites powders were consolidated by powder metallurgy (PM) followed by sintering or high-pressure torsion (HPT) to study the effect of the different processing methods on microstructure evolution and mechanical properties. HPT contributes in producing fully dense samples with a relative density higher than those processed by PM followed by sintering. Bimodal and trimodal microstructures with a mixture of ultrafine grain (UFG) and micro or nano grain sizes were noted in the case of Cu and Cu-SiC HPTed samples, respectively. The increase of the SiC volume fraction (SiC%) produces smaller grain size with higher fractions of high angle grain boundaries (HAGBs) in the HPTed Cu-SiC samples than that in the case of HPTed Cu sample. The HPT under a pressure of 10 GPa and 15 revolutions was effective to achieve a complete fragmentation of SiC particles down to ultrafine particle size. HPT processing of Cu and Cu-SiC composites enhanced the mechanical properties (hardness and tensile strength) with conserving a reasonable degree of ductility (elongation%). The yield strength of the samples was estimated based on the microstructure observations and processing parameters by different models correctly with an error range of 5.1–1% from the experiential results.