Title : In situ insights into micron scale plasticity
Abstract:
Elementary plastic deformation events (dislocation avalanches, mechanical, martensitic transformation, etc.) are typically concealed in the deformation curves as the curves provide only “average information”. This is due to the simultaneous plastic activity at a multitude of locations within the sample as well as due to the limited force and time resolution of deformation devices. On the other hand, supplementary techniques such as high-resolution/ultra-fast imaging and acoustic emission, if implemented correctly, allow for detailed characterization of the activity of deformation mechanisms. Here, we apply these techniques to characterize metallic materials at macro- down to micro-scales, where the deformation behavior becomes rather erratic. Using these techniques, spatial and temporal patterns in seemingly random plastic events can be recognized by employing various statistical analyzes.
As a practicable example, we present compression experiments on micron-scale Zn specimens performed using a unique experimental set-up capable of detecting weak acoustic “signatures” of dislocation slip. Robust correlations are observed between the energies of deformation events and the emitted acoustic signals induced by the collective dissipative motion of dislocations. Moreover, we show by statistical analyzes that despite fundamental differences in deformation mechanisms (and involved length- and time-scales), dislocation avalanches and earthquakes are essentially alike.
The obtained data contribute to the fundamental understanding of deformation dynamics in crystalline materials and can be utilized in designing future metallic materials as well as emerging micron-size mechanical devices.
Audience Take Away Notes:
- The missing link between the properties of acoustic signals and the corresponding local deformation events is established for the first time
- Scale-free deformation dynamics is manifested across different scales and conditions using the acoustic emission technique
- The results contribute to the fundamental understanding of (inherently stochastic) deformation dynamics in crystalline materials
