Combined crystal plasticity–phase field fracture simulation to understanding particle cracking in recycled 6xxx aluminium alloy

Increasing the use of recycled aluminium alloys in wrought applications requires increasing tolerance to impurities such as iron. These impurities form brittle constituent particles that can crack or de-bond, leading to a reduction in formability. The fraction, size, shape, and distribution of particles all have an influence on mechanical properties and formability. Understanding the significance of each variable is difficult to study experimentally as they cannot be independently controlled. In this work, a modelling approach was instead used, where a coupled crystal plasticity and phase field fracture model was applied to predict the critical applied strain to initiate particle fracture. Both polycrystalline volume elements and simplified microstructures in which each variable can be independently controlled were investigated. The model has been used to explore the effect of particle shape, location, distribution, and clustering. Particles with high aspect ratio and those in closely spaced clusters have been predicted to be particularly prone to cracking at low levels of applied strain. The results have implications in the design of recycling tolerant aluminium alloys.