Hot deformation behavior and microstructure evolution of the spray deposited and secondary hot extruded 2195 Al–Li alloy

Abstract

This work aims to investigate the influence of hot deformation parameters on the microstructure evolution and deformation behavior of the extruded 2195 Al–Li alloy, as well as to explore its optimized hot deformation windows based on the hot compression tests carried out on a Gleeble-1500 thermo-mechanical simulator in the temperature range 370–520 °C and with the strain rate of 0.001–10 s−1. The results revealed that the extruded 2195 Al–Li alloy plate with a large aspect ratio had a lower deformation activation energy with respect to the spray deposited and as-cast 2195 Al–Li alloys owing to the existence of a large number of coarse second phases and LAGBs in the extruded plate. The optimized hot deformation temperature of the alloy ranged from 405 °C to 490 °C with a strain rate from 0.001 to 0.1 s−1. Hot deformation under the optimized conditions led to the occurrence of continuous dynamic recrystallization and resultant microstructure refinement. Although the occurrence of continuous dynamic recrystallization weakened the <101> deformation texture, but triggered another texture component with <001>//ND. Deformation at low temperature and high strain rate induced flow instability due to insufficient dynamic softening. In addition, the flow instability at a temperature higher than 490 °C arose from partial remelting of Al2Cu phase along grain boundaries. The work can provide an effective guidance for the designation of secondary hot processing of the extruded 2195 Al–Li alloy.