In line with the metallographic tests, the precipitated particles in the aged 7050 aluminum sample (T6) at the typical positions have been studied by TEM (Transmission Electron Microscope), the TEM images and the associated diffraction patterns are shown in Fig. 11. It can be seen in Fig. 11(a) that the precipitates, which
are mainly composed of g’ (located at 1/3(022) and 2/3(022))
and Al3Zr particles (located at 1/2(022)), appear fine and dense.increasing distance from the quenched surface, the amount of the equilibrium-state coarse g particles increases, as shown in Fig. 11(b–d). The Al3Zr dispersoids act as effective nucleation sites for heterogeneous precipitation during slow quenching, and this can be clearly observed in Fig. 11(d).