Abstract: Lost of dispersed strengthening phases exist in wrought aluminum alloy. Meanwhile, the residual strain fields are generated around the precipitated phase. Residual strain fields are detrimental to the strength, fatigue life, dimensional stability, stress corrosion resistance, and other material performances. The position of high order Laue zone(HOLZ) lines in the convergent beam electron diffraction(CBED) pattern is very sensitive to the changes in lattice parameters. According to the HOLZ line shifts and rotation, the residual strain of composite can be measured. Convergent beam electron diffraction technique is employed to explore the residual stress in the matrix of the Al12Zn2.4Mg1.1Cu alloy after heat treatment. The analytical results demonstrated that there existed obvious residual strain nearby precipitations, the residual stress is reduced as the distance increase in precipitation relative to the distance it could reach 210 MPa at the distance of 5 nm, away from the interface at the 45 nm and 85 nm, respectively, 202 MPa and 145 MPa.

Key words: Aluminium alloy, Convergent beam electron diffraction, Residual stress