Characterization of Cu/SiC surface composite produced by friction stir processing

The main aim of this work was to obtain a copper matrix surface composite using friction stir processing (FSP). The reinforced phase was SiC particles with an average size of 5 mm. The effect of the reinforcement on the microstructure, hardness and wear behaviour were analysed. The friction treatment was carried out using a truncated cone-shaped tool with a threaded side surface. Multi-chamber technology was used to produce the composite microstructure in the copper surface layer. Changes in the material microstructure were assessed by light microscopy and scanning electron microscopy. Comparative measurement of the hardness of the initial and treated material as well as wear resistance tests were also carried out. A favourable effect of the surface treatment on the microstructure and properties of the copper was found. As a result of the friction treatment there was strong grain refinement in the copper surface layer. The average grain size in the stirring zone was about 3 mm and was over 21 times smaller than the average grain size in the initial material. Intensive dispersion of the SiC particles in the modified layer was also found, leading to the formation of a copper matrix composite. The effect of microstructural changes in the surface layer of the material and formation of the surface composite was an over two-fold increase in the hardness of the material and an increase in wear resistance.