Multi-axial strain controlled cyclic deformation induced phase transitions in aluminium: An atomistic simulation-based study

Aluminium plays a vital role in large-scale manufacturing for the aerospace and automotive industries owing to its low density and excellent corrosion resistance. Additionally, it is extensively utilized in packaging industries, including those for food, electronics, and pharmaceuticals. This study employs large-scale molecular dynamics simulations to examine the structural evolution and phase transitions of aluminium during multi-axial strain-controlled cyclic deformation. Uniaxial, biaxial, and triaxial cyclic loading resulted in distinct deformation paths, including dislocation nucleation, grain coarsening, and FCC to BCC/HCP transitions. Quantitative study showed yield strength of 1.807 GPa (Uniaxial) and 4.67 GPa (Triaxial), with up to 50% FCC to BCC phase transition during the multi-axial cyclic deformation. Mechanistically, BCC formation was trigged by localised stress concentrations and defect interactions, which provided an alternative pathway for accommodating cyclic strain. Sigificantly, these predicted FCC to BCC/HCP transitions align with earlier high-pressure experiments and first-principles computations, indicating the validity of our MD findings. Thus, the findings reveal novel atomistic insights into stress-induced phase stability in aluminium, with implications for fatigue resistance and microstructural design. • Multiaxial cyclic loading induces phase transition from fcc to bcc in aluminium. • Bcc regions nucleate at grain boundaries and evolve under cyclic compression. • Bcc phase formation is associated with grain coarsening and low dislocation density. • Biaxial and triaxial loading modes show distinct microstructural transition paths. • Controlled cyclic deformation offers a new way to enhance aluminium properties.