Slip Activity and Precipitation Behaviors of Al-Cu-Li Alloy During High Temperature Tensile Deformation

The present work investigates the deformation mechanisms of the Al-Cu-Li alloy from room temperature (RT) to 300°C by in-situ electron backscattering diffraction and slip trace analysis method. The Al-Cu-Li alloy ingot was rolled and annealed to achieve an average grain size of ~ 180µm. Tensile test results show that at 100°C, the sample has similar yield strength (203 MPa) as RT sample, but the elongation reaches a peak value of 33%. Upon further increasing the temperature, the yield strength and the elongation start to decline and the elongation is reduced to 9.5% at 300°C. Statistical analysis on the slip behaviors of multiple grains shows that more grains activate type II slip (multiple slip systems) at 100°C than at RT, which compensates for the yield strength loss due to softening and contributes to a higher ductility as it accommodates the stress from different directions. In addition, the increasing tensile temperature facilitates the growth of θ’ phase inside the grains and along grain boundaries, which leads to a significant decrease in elongation and introduces work hardening by forming dislocation rings.

Graphical Abstract