Abstract
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•HPT produces fully dense Cu and Cu-SiC with bimodal and trimodal microstructures.•HPT reduces the Cu grain size to 0.95 and 0.3µm in the case of Cu and Cu–20%SiC.•HPT was effective in fragmentation of SiC down to ultrafine particle size.•HPT improves tensile strength and hardness with conserving fair level of ductility.•The tensile yield strength was correctly estimated with error ranged from 1% to 5%.
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 10GPa 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.