[SY-L4] Symposium L-4

[SY-L4] Temporal and spatial plastic instability of micrometer-scaled materials

Invited

^○Yinan Cui¹, Giacomo Po¹, Nasr Ghoniem¹ (1. Mechanical and Aerospace Engineering Department, University of California, Los Angeles, United States of America)

Suppressing plastic instability is a critical goal to improve deformability and ductility in a wide variety of engineering applications. At temporal scale, plastic instability is manifested as intermittent burst and dislocation avalanches, leading to uncontrollable deformation. At spatial scale, plastic instability is manifested as the onset of flow localization, leading to sudden failure. While insight in the physical origin of plastic instability accumulates, the need for a quantitative description of temporal and spatial plastic instability remains challenged due to the lack of clear quantitative relation correlating deformation behavior with microstructural features. Here, we will discuss the quantitative description method of temporal and spatial plastic instability, and present a very simple model to predict them based on the idea of stochastic activation of dislocations sources. Combined with systematic discrete dislocation dynamics simulations, we will present that even though power law scaling is widely used to describe the statistical distribution of strain burst magnitude, power law scaling does not tell the whole story at temporal scale. At spatial scale, highly-irradiated materials will be taken as an example. We will unravel the mystery of how and why irradiation-induced defects enhance or inhibit plastic instability, and how and why dislocation channels arise, and what governs their width.