Effect of varied initial dislocation densities on the anisotropic behavior of creep-aging in Al–Cu–Li alloy

Accurate forming predictions for the third-generation Al–Cu–Li alloys challenged by anisotropic creep-aging (CA) behavior. The creep-aging anisotropic behavior of Al–Cu–Li alloys with different initial dislocation densities is not clear. The anisotropy of creep behavior and yield strength in Al–Cu–Li alloy under high dislocation density (T3) and low dislocation density (T4) conditions have been experimentally investigated. The results show that the in-plane anisotropy (IPA) of creep strain decreased from 59.3% and 50.2% to 7.2% and 8.3% for T4 and T3 samples, respectively. It is found that the T₁ phase significantly suppresses the anisotropy of creep strain, the faster the precipitation rate of the T₁ phase, the more diffuse the distribution of the inhibitory effect is more obvious, the T₁ phase inhomogeneous coarsening of the creep strain inhibition effect is slightly weakened. The yield strength IPA of T4 and T3 samples decreased from 6.88% and 19.47% to 5.66% and 6.41%, respectively. The higher initial dislocation density promotes a uniform and diffuse distribution of the T₁ phase, which greatly suppresses the yield strength anisotropy. Different initial dislocation densities lead to different precipitation behaviors of the T₁ phase, which should be responsible for the difference in the anisotropy of CA behavior, as is the yield strength.