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

Abstract

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 and fibers in this work. The results show that more slip systems are activated in the fiber, forming LAGBs through dislocations cross-slip and entanglement, thereby stimulating the CDRX. The number of slip systems that be activated in the 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 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.

Keywords

• Heterogeneous fiber structure
• Deformation mechanism
• Deformation compatibility
• Al–Cu–Li alloy