Insights into flow stress and work hardening behaviors of a precipitation hardening AlMgScZr alloy: Experiments and modeling

Flow stress and work hardening behaviors, as two important aspects of mechanical behaviors, have been studied extensively and their interpretation for the case of pure metals via dislocation theory is well established. The introduction of precipitates inevitably affects the flow stress and work hardening rate, since the precipitates can evidently change the dislocation behaviors, both their gliding facilities and their storage mechanisms. Thus, different precipitate-dislocation interaction modes (i.e. shearing and bypassing mechanisms) would lead to different dislocation behaviors and resultant different flow stress and work hardening behaviors. In this study, we investigate the influence of shearable, non-shearable and mixed shearable/non-shearable precipitates on flow stress and work hardening behaviors in the case of AlMgScZr alloys, where precipitates and solid solution can be decoupled, based on experiments and a modified dislocation-based model. We show that, the introduction of shearable precipitates and shearable/ non-shearable transition have important effects on flow stress and work hardening behaviors. By quantitatively characterizing different precipitate-dislocation interactions and the evolution of dislocation density during the deformation, the intrinsic influencing mechanisms of precipitates on flow stress and work hardening behaviors are demonstrated.