A robust dislocation line tension model considering obstacle strength distribution for yield strength prediction of an Al–Cu–Li alloy

Abstract

In this study, the yield strength of AA2195 (Al–Cu–Li) alloy as a function of ageing time was determined using a dislocation line tension model. The model simulates the dislocation motion through an array of point obstacles, which represent forest dislocations and semi-coherent precipitates (T1 and θ’). These obstacles were distributed within the simulation environment according to experimentally derived areal densities of the T1 and θ’ precipitates and the forest dislocations. Point obstacles symbolizing T1 and θ’ precipitates were assigned a strength value derived from a log–normal approximation of the size distribution of the precipitates as observed using transmission electron microscopy. A notable agreement between experimental and simulated results emerged when the strength distribution of point obstacles representing precipitates was considered in the simulations. Conversely, simulations that assumed uniform strength of point obstacles led to an underestimation of the yield stress. This work proposes a framework that contemplates both spatial and strength distribution of point obstacles, offering an advance approach that outperforms previous yield strength models based on a linear superposition of strengthening mechanisms.