New cubic precipitate in Al-3.5Cu-1.0Li-0.5In (wt.%) alloy

The precipitations of Al-3.5Cu-0.7Li alloy aging at 175 °C were studied by HREM and 3DAP. A new cubic phase precipitate has been discovered as the dominant phase, which is assumed having a cubic structure with a ≈ 0.83 nm and the orientation relationship with the matrix is: (001)_p//(001)_α, 010]_p//010]_α. Considering the good match of observed and simulated HREM images, we suggest that the studied cubic phase is a variant of Al₅Cu₆Mg₂ with Li substituting the Mg positions.