Fig. 4 Orientation image of BM and SZs: (a) BM, (b) SAZ of as-welded SZ,
(c) PAZ of as-welded SZ, (d) SAZ of rolled SZ (3 mm), (e) SAZ of rolled
SZ (3 mm)
The TEM images of as-welded PAZ and rolled PAZ in the SZ with a
thickness of 2 mm are shown in Fig. 5. It was observed from the Fig. 5
(a) and (b). Mg2Si particle (with an average size of 57
nm) and Al-Fe-Cr-Si particle (with an average size of 145 nm) generated
in the as-welded PAZ. The characterization of Mg2Si
particle is shown in Fig. 6 (a)-(c). According to the results of EDS and
SEAD, the fine (Mg. Si)-rich particles were concluded as
Mg2Si particles. The coarse particle in Fig. 5 was (Fe,
Cr, Si)-rich Al-Fe-Cr-Si particles as shown in Fig. 6 (d). The
low-density dislocation with an approximately density of 1e9
cm-2 was observed from Fig. 5 (a) and (b). After
rolling process, the particle size of Mg2Si and
Al-Fe-Cr-Si has not been changed. However, the dislocation density was
greatly improved to approximately 1e11 cm-2 as shown
in Fig. 5 (c) and (d).