Atomic-scale observations of dislocation junction formation and decomposition processes in gold

Abstract

Work hardening originates from the impediment of dislocation motion. In fcc metals, a crucial obstacle to dislocation motion is a stair-rod dislocation (SRD), which has V-shaped stacking faults (SFs) structure. Thus, the density of the SRDs during deformation should govern the behavior of work hardening. However, the SRD formation and decomposition mechanisms during deformation have not been well understood due to the experimental difficulties in direct visualization of the dynamic evolution processes. Here, we show the SRD formation and decomposition processes in single crystalline gold at the atomic scale via in situ straining experiment inside a scanning transmission electron microscope. Our atomic-scale direct observations revealed that the SF width has a crucial influence on the probability of the SRD formation and the stability against the SRD decomposition. Our findings indicate the dependence of work hardening on SF width, which offers a renewed perspective on the puzzle of work hardening phenomenon.