Microstructural, mechanical and tribological characterization of Cu-Co-Ni-Be alloy processed via equal channel angular pressing

Effects of different processes including various combinations of equal channel angular pressing (ECAP) and aging on the microstructure, mechanical and tribological properties of the quadruple Cu-Co-Ni-Be alloy were investigated. ECAP process results in a significant grain refinement and brings about an ultrafine-grained (UFG) microstructure. Grain boundary strengthening and strain hardening mechanisms increase the strength and hardness of the ECAPed alloy significantly. Subsequent aging of the ECAPed sample results in a further increment in the hardness and strength due to the formation of precipitates besides the UFG structure. Wear resistance and operative wear mechanisms of the alloy depend on the applied processes strongly. ECAPed + aged sample with the highest hardness exhibit the highest wear resistance among all samples. Detailed investigations show that various wear mechanisms are operative in the Cu-Co-Ni-Be alloy samples. Adhesive wear is the mean wear mechanism in the initial and aged samples, and it is more prominent in the initial sample than the aged one due to the its quite softer and more ductile nature. Limited abrasive wear is also operative in these samples. delamination wear, on the other hand, is observed to be the main wear mechanism in the ECAPed and ECAPed + aged samples. Wear particles generated due to the delamination process cause three-body abrasive wear as an another wear mechanism in the UFG samples. Besides, oxidative wear is also operative in these samples and it is more prominent than that of the initial and aged ones. The achieved results show that UFG formation by any manner and subsequent aging processes are effective to improve wear resistance of the Cu-Co-Ni-Be alloys.