The effect of stacking fault energy on acoustic emission in pure metals with face-centered crystal

Many questions remain open in the understanding the role of microstructural factors in the acoustic emission (AE) phenomenon occurring in deforming materials. A comparative analysis of AE time parameters in tensile testing of pure aluminum, copper, silver and nickel specimens having very different values of stacking fault energy (SFE) was undertaken in the present work to clarify the SFE effect on the AE signal. Continuous digital wideband recording was used for AE waveform registration, which offers the possibility to avoid the threshold discriminators and to analyze a continuous AE signal generated during plastic deformation mediated by dislocation mechanisms. The power of the AE signal were selected as the descriptive parameters. Following the evolution of dislocation structures, the AE energy parameters were demonstrated to have a similar behavior in all investigated materials, i.e. the AE level increases sharply at the onset of plastic flow and then decays gradually during the uniform strain hardening stage. However, the absolute values of the AE amplitude and energy differ significantly depending on SFE. It was shown unambiguously that in contrast to expectations, the AE energy parameters reduce as the SFE value increases. This effect is discussed qualitatively in terms of the features of dislocation behavior, which are governed by the SFE value.