Fig. 8 TEM (a, b) and HRTEM images
(c) of matrix precipitates in BM sample. The inverse FFT images after
mask to the phases in (c) image are shown in (d).
As shown in Fig. 9a, sub-grains could also be observed in AS-HAZ. Some
discontinuous chain-typed 𝜂 (MgZn2) equilibrium phases
formed in grain boundary and the PFZ were obviously observed. As
compared with BM, the size of 𝜂′ precipitates in grains increased
slightly (Fig. 9b). It should be noted that the projections of some
precipitates showed short rod-shaped morphology while the others
displayed the round morphology, depending on the direction of
observation [27]. According to HRTEM observation, all of the 𝜂′
precipitates remain semi-coherent relationship with matrix (Fig. 9c and
9d). No clear GPII zones were identified in AS-HAZ.