Prediction of the shear strength of aluminum with θ phase inclusions based on precipitate statistics, dislocation and molecular dynamics

Abstract We propose a three-stage technique for predicting the flow stress of aluminum alloy combining atomic calculations, parameterizing the dislocation–precipitate interaction model, and 2D dislocation dynamics. The precipitates of θ phase in aluminum matrix are considered as the object of atomistic calculations in this work. It is shown that, in contrast to the previously studied precipitates of the aluminum-copper system (GP zones, θ” and θ’ phases), θ phase appears as uncuttable inclusion during our atomistic study demonstrating only significant bending of its shape. The obtained rate and temperature dependencies of the average stress in the system are used to find the parameters of the previously proposed model of the dislocation–precipitate interaction (Krasnikov and Mayer, 2019; Krasnikov et al., 2020) in the case of θ phase. After fitting of the model parameters, the equation of motion of the dislocation in the presence of inclusions of θ phase is used in 2D dislocation dynamics. The dislocation dynamics model employs the experimental data on the size distribution of precipitates (Zuiko and Kaibyshev, 2018). The obtained values of the flow stresses of alloy demonstrate good agreement with the experimental results, and the dislocation dynamics model predicts the correct value of the thermal softening of alloy. The model predicts a strict dependence of the flow stress of alloy on the dispersion of the size distribution of precipitates at the constant average size.