Cellular automata simulation of cavity nucleation, growth, and coalescence during creep of artificially-aged AA2017

This study develops a cellular automata simulation integrated with governing rate equations to assess the cavitation and its progress during creep of artificially aged AA2017. The model incorporates both diffusion- and strain-controlled growth mechanisms, capturing the progression and interactions of cavities across the microstructure. The samples were solution-treated and then artificially aged at 210°C for 6 hours then, the creep tests were conducted at a temperature of 160°C and stress of 250 MPa for durations of 1, 3, 5, and 7 days to provide empirical data for the model calibration and determination of material constants while the other set of creep tests was carried out at 150°C and 260 MPa at different creep durations for validation of simulated results. Moreover, the optical and the scanning electron microscopy were utilized to characterize cavity morphology and their distribution. The model predictions were consistent with the experimental findings demonstrating that cavity coalescence becomes prominent when the cavity volume fraction exceeds 0.3% for the case of examined alloy. The proposed model was employed to investigate cavitation under different conditions. Based on the simulation results, it was found that increasing the precipitate size from 2.93 μm to 9.73 μm, decreased the cavity volume fraction over various creep durations. However, the finer grains with reduced grain size from 52.3 μm to 18.6 μm, intensified the cavitation and coalescence by providing more nucleation sites.