Deformation mechanism of as-extruded Al–Cu–Li alloy with heterogeneous fiber structure

The Al–Cu–Li alloy has poor plasticity and hot workability, making it difficult to form by single-pass working, so the multi-stage thermomechanical processing is usually required. However, there is a general distinctly heterogeneous fiber structure in deformed alloys, which has non-negligible effects on the stability and formability of subsequent deformation. Therefore, the deformation mechanism of heterogeneous fibers and intergranular deformation compatibility mechanism are investigated for as-extruded Al–Cu–Li alloys with <111> and <100> fibers in this work. The results show that more slip systems are activated in the <100> fiber, forming LAGBs through dislocations cross-slip and entanglement, thereby stimulating the CDRX. The number of slip systems that be activated in the <111> fiber is relatively smaller, and the dislocations are dominated by single-slip and are easily pinned by the coarsening precipitate, thus activating the DDRX mechanism to force the grains to transform into the <110> fiber. To coordinate the fiber deformation, the DDRX driven by dislocations from precipitate pinning is activated to relieve stress concentration. This study can provide theoretical guidance for rationally formulating the multi-stage thermomechanical processing regime of Al–Cu–Li alloys.