Deformation and Fracture of Copper and Silicon During Indentation Acoustic Emission Measurements

Abstract

The acoustic emission (AE) signals during different phases in indentation (loading, dwell, and unloading times) of ductile Cu and brittle Si were studied. The effect of load and time of loading on the AE parameters were studied. The waveforms and dominant frequency ranges were analyzed. In order to clarify the effect of friction during indentation on the AE signals, the indentation was performed through lubricant film. It was shown that the main AE signals were observed just in the loading phase in indentation of Cu. The low-amplitude wide band noise-like high-frequency-range AE signals, observed during indentation of Cu, can be associated with breakaway and jump in the motion of dislocations. Much larger duration of the AE signals in indentation of Cu indicates a substantially larger dislocation glide in annealed Cu in comparison with limited deformation in Si. The waveform during the indentation of brittle Si presents strong burst-type AE signals. Indentation of Si is accompanied by high-energy and low frequency AE signals characterizing development of the dominant damage and limiting level of plastic deformation. Indentation through the lubricant film leads to the formation of flaky cleavage and swelling around the impression.