## 3 Results and Discussion
### Microstructural Observation
As shown in Table 2 and Figure 6a,c, alloy A(0.1 Zr) after the two-stage homogenization could restrain the recrystallization of the T6 alloy more effectively than after the one-stage homogenization. This result can also be attributed to the phenomenon caused by the significantly refined Al\({}_{3}\)Zr dispersed grains of the two-stage homogenized  
Figure 4: Cross-sectional microstructures of as-cold-rolled specimens observed by optical microscope (OM); (**a**) 1-Hom. alloy A(0.1 Zr); (**b**) 1-Hom. alloy B(0.05 Sc); (**c**) 2-Hom. alloy A(0.1 Zr); (**d**) 2-Hom. alloy B(0.05 Sc); (**e**) cross-sectional direction. ND, normal direction; RD, rolling direction. alloy. However, after different homogenization heat treatments, because the difference of the dispersed Al\({}_{3}\)Sc grain size of alloy B(0.05 Sc) was smaller (\(\sim\)10%), the degrees of the recrystallization of their T6 alloys had no obvious difference. The recrystallization ratios were both about 33%, as shown in Table 2 and Figure 6b,d. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Grain Measurement Alloys** & **RD (\(\mu\)m)** & **ND (\(\mu\)m)** & **Aspect Ratio** &
\begin{tabular}{c} **Recrystallization** \\ **Fraction (\%)** \\ \end{tabular} \\ \hline Alloy A(0.1 Zr) & 1-Hom.(a) & 78.3 (20.5) & 17.4 (6.0) & 4.5 (1.5) & 66.0\% \\  & 2-Hom.(b) & 70.0 (36.3) & 15.9 (4.5) & 4.4 (0.9) & 59.0\% \\  & \([(\rm{b-a})/\rm{a}]*100\%\) & \(-11.00\%\) (0.05) & \(-8.60\%\) (0.15) & & \\ \hline Alloy B(0.05 Sc) & 1-Hom.(a) & 40.7 (10.2) & 14.6 (1.5) & 2.8 (0.6) & 34.0\% \\  & \([(\rm{b-a})/\rm{a}]*100\%\) & \(-4.60\%\) (0.22) & \(-2.00\%\) (0.16) & & \\ \hline \hline \end{tabular}  
0, standard deviation; RD, rolling direction; ND, normal direction; aspect ratio: ratio of length of rolling direction and normal direction.  
\end{table} 
Table 2: Grain size, aspect ratio and recrystallization fraction by different homogenization after T6 heat treatment of alloy A and alloy B.  
Figure 5: Microstructures observation by OM after T6 temper (1 h solution treatment and aging): (**a**) 1-Hom. alloy A(0.1 Zr); (**b**) 1-Hom. alloy B(0.05 Sc); (**c**) 2-Hom. alloy A(0.1 Zr); (**d**) 2-Hom. alloy B(0.05 Sc); (**e**) cross-sectional direction. ND, normal direction; RD, rolling direction. The analysis of the grains of the T6 alloys in Figure 6 shows that the grains had a clear preferred orientation. The grains tended to grow in the rolling direction (RD). This phenomenon was because after the cold working, the fine high-temperature stable Al\({}_{3}\)Zr and Al\({}_{3}\)Sc dispersed grains arranged along the texture, and restrained the grains from growing toward the alignment direction (ND) of the texture [23,24]. After a careful analysis, the directional crystals were composed of recrystallized directional crystals and  
Figure 6: Euler angle colored electron backscattered diffraction (EBSD) maps of T6 state of (**a**) 1-Hom. alloy A(0.1 Zr); (**b**) 1-Hom. alloy B(0.05 Sc); (**c**) 2-Hom. alloy A(0.1 Zr); (**d**) 2-Hom. alloy B(0.05 Sc); (**e**) IPF(Inverse Pole Figure) coloring map and cross-sectional direction. ND, normal direction; RD, rolling direction. coarse woven crystals. The coarse grains in Figure 6 (as shown by the arrow in the figure) analyzed by the Channel5 (Tango) software were actually the un-recrystallized woven crystal microstructures left after the cold working process. The grains contained many dense sub-grain boundaries. The intercept method was used to calculate the grain diameters of the recrystallized directional grains. In the summary in Table 2, it can be seen that the T6 recrystallized grain aspect ratios of the A(0.1 Zr) alloy and the B(0.05 Sc) alloy, whether after the one-stage or two-stage homogenization heat treatments, their T6 recrystallized grain aspect ratios are approximately the same, about 4.4 and 2.7, respectively.