ACOUSTIC-EMISSION - A PROBE INTO DISLOCATION DYNAMICS IN PLASTICITY

Acoustic emission (AE) from deforming copper and its dilute alloys was recorded at varied frequencies at room temperature and up to 500°C. All results proved to be compatible with the spurt-like dislocation movement between two bounds being the AE generating event. AE presents a maximum in the beginning of stage II deformation when event lifetimes in the range of microseconds correspond to the recording frequency. Furthermore, AE decreases rapidly with decreasing event size (by work-hardening) resp. decreasing dislocation mobility (by elevated temperature or solute content). In copper viscous dislocation movement achieves some m/s. As event bounds dislocation or cell walls should act. Solution hardening increases the stress exponent in dislocation mobility, but it is demonstrated, that doubt is advisable in some of such results. So AE proves to serve as probe into dislocation dynamics inside the bulk of a work-hardening metal. © 1990.