## 3 Results and Discussion
### Microstructure and Phase Analysis after the Single and Two-Stage Aging Processes
#### 3.2.2 EDS and Phase Analysis after Aging Treatments
zones present as a heterogeneous core demonstrated limited distribution of the precipitated phase after the secondary aging process. It is generally believed that \(\alpha\)-Zr and Mg have the same h.c.p lattice structure. The Zn\({}_{2}\)Zr\({}_{3}\) phase that precipitated in the solid solution process did not undergo any obvious changes during the aging process [20]. The EDS results show that the atomic ratios of Mg, Zn, and Zr are 54.18%, 18.51%, and 27.31%, respectively. Figure 7c shows the semi-elliptical precipitates that are found in the grain boundaries. The energy spectra of the flaky phase, granular phase, and semi-elliptic precipitated phase are similar and are demonstrated to be composed of Mg and Nd and to belong to different forms of the same substance. The precipitated Mg\({}_{12}\)Nd phase in the as-compressed microstructure has three forms: the bulk phase in the grain boundary, the flake phase in the grain boundary, and the granular phase near the grain boundary. Figure 7c shows the intragranular electron diffraction pattern of the selected area. The bright large spots in the calibration diagram are the diffraction patterns of the \(\alpha\)-Mg matrix [21; 22; 23; 24; 25], while the small spots in the 1/2 matrix are those of Mg\({}_{12}\)Nd and demonstrate somewhat of a coherent relationship with the \(\alpha\)-Mg matrix. Figure 7d shows the precipitation phase of Mg\({}_{12}\)Nd at the grain boundary. There are obvious precipitates at the grain boundary,  
\begin{table}
\begin{tabular}{l c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Element**} & \multicolumn{2}{c}{**Spot**} & \multirow{2}{*}{**Mass \%**} & \multirow{2}{*}{**Atom \%**} & \multirow{2}{*}{**Spot**} & \multirow{2}{*}{**Mass \%**} & \multirow{2}{*}{**Atom \%**} & \multirow{2}{*}{**Spot**} & \multirow{2}{*}{**Mass \%**} & \multirow{2}{*}{**Atom \%**} & \multirow{2}{*}{**Spot**} & \multirow{2}{*}{**Mass \%**} & \multirow{2}{*}{**Atom \%**} \\  & & & & & & & & Position & & Position & \\ \hline Mg K & 60.46 & 88.26 & 83.72 & 96.64 & & 75.75 & 93.71 & & 81.70 & 95.70 \\ Nd L & Spot 1 in & 32.28 & 7.94 & Spot 3 in & 15.06 & 2.93 & Spot 1 in & 19.14 & 3.99 & Spot 3 in & 15.15 & 2.99 \\ Zn K & Figure 8a & 6.34 & 3.44 & Figure 8a & 0.47 & 0.20 & Figure 8b & 4.74 & 2.18 & Figure 8b & 2.64 & 1.15 \\ Zr L & & 0.92 & 0.36 & & 0.75 & 0.23 &linear precipitates near the grain boundary, and spherical precipitates with a diameter of 1-2 \(\upmu\)m that are distributed in the crystal. The precipitates that are at the grain boundary are in either the Mg\({}_{9}\)Nd or Mg\({}_{12}\)(Nd, Zn) phase [19; 20]. These particles are supposed to be Mg\({}_{12}\)Nd, and the smaller particles are arranged in a linear fashion around dislocations or grain boundaries [28; 29]. Figure 8: Phase analysis of as-compressed ZM6 before and after the two-stage aging process: (**a**) Grain boundary precipitate and EDS analysis after the TAST process; (**b**) TEM and EDS of continuously precipitated Zn\({}_{2}\)Zr\({}_{3}\) phase after the TAST process; (**c**) TEM of the grainy precipitated phase and selected area diffraction patterns of spotted state precipitated Mg\({}_{12}\)Nd phase after the TAST process; (**d**) TEM bright-field image and TEM dark-field images of precipitates after the TAST process.