Microstructural, mechanical and acoustic emission-assisted wear characterization of equal channel angular pressed (ECAP) low stacking fault energy brass

Cu-37wt.%Zn brass samples have been ECAP processed using 1, 2, and 3 passes and then characterized using TEM, compression and tensile tests, indentation, scratching, wear with simultaneous monitoring acoustic emission and vibration acceleration. Mechanical tests showed higher mechanical strength, hardness, wear resistance as well as other characteristics of the ECAPed samples. TEM study demonstrated the microstructural evolution of samples after 1-, 2-3 pass ECAP. Structurally inhomogeneous microstructure composed of primary twin stacks and twin-free zones has been obtained after 1-pass ECAP. Further ECAP on these samples allowed revealing two deformation processes such as microtwinning in the twin-free zone and dislocation glide along the primary twin boundaries. The latter increased the inter-twin misorientation and transformed them into misoriented band structures. Wear test results revealed intense adhesion transfer and reduced wear on samples after ECAP. Acoustic emission and vibration acceleration signals have been obtained during wear and then used to characterize the wear mechanism. Primary twinning and microtwinning in the as-received and 1-pass ECAP samples, respectively, was identified by the AE signal median frequency peaks. On the contrary, the median frequency drops corresponded to the subsurface fracture development in 2- and 3-pass ECAP samples.