STUDY OF DEFORMATION AND FRACTURE OF COPPER AND SILICONE BY ACOUSTIC EMISSION

A connection between the scratching and the acoustic emission (AE) signals emitted during material removal, plastic deformation and damage development is studied. Cu and Si samples were scratched by Knoop indenter The following AE parameters as the number of counts (HITs), frequency range, the energy and the energy rate were evaluated. The waveforms were analyzed. The AE waveforms during scratching and rolling of Cu present low-amplitude wide noisy band high frequency range. The low-frequency range in scratching of Cu is associated with the ploughing. Brittle fracture of Si is accompanied by accumulation of the shear stress waves leading finally to formation of shear bands, cracking around and inside the track and microchip formation Scratching of brittle Si is characterized by scrubbing damage in nanoscale (a depth of scratching is 50-100 nm) and the development of microchips in the track formed each 40-50 µm. Two typical signals under scratching of Si were revealed: first one is burst–shape waveform corresponding to the formation of microship and microcracking damage, and the second one presenting the separated individual bursts of relatively high amplitude. The effect of sliding velocity on the AE parameters during scratching of Cu and Si was analyzed. It was found that practically all the AE parameters were larger under scratching with low velocity, V = 1 µm/s in comparison to relatively high velocity, 100 mm/s.