Deformation created by the impact of small angular and spherical particles on individual grains

Damage mechanism induced by 25 μm, average size, angular and spherical particles impacting the surface of Cu-30% Zn (α-brass) was investigated. Particles were impacted to the surface at normal incidence, with a velocity of 12 m/s. The primary characterization tools used were scanning electron microscopy (SEM) and atomic force microscopy (AFM). AFM allowed for the measurement of impact profiles, those of the cut surface and material pile-ups. Deformed volume by the particles was limited to a single grain. The impacts produced were asymmetrical and the chip formation was also highly directional. These asymmetries were the same in a single grain but they varied from grain to grain. Regardless of particle geometry, similar deformation features were observed on the target surface impacted by angular and spherical particles. The direction of the deformation appeared to be imposed by the mechanical response of the deforming grain. Since the deformation induced by a single impact is limited to a single grain, anisotropic mechanical properties of the individual grains observed were attributed to their impact damage morphology.