## 3 Results and Discussion  
### Phase Composition and Microstructure Characteristics of As-Melt Alloys  
Figure 2a presents the XRD pattern of as-cast pure Mg. Figure 2b shows the XRD patterns of as-cast Mg-10 Al, Mg-20 Al, and Mg-30 Al alloys. Figure 2c displays the XRD patterns of as-cast Mg-10 Zn, Mg-20 Zn, and Mg-30 Zn alloys. For as-cast pure Mg, only the Bragg peaks of Mg were observed. For Mg-10 Al, Mg-20 Al, and Mg-30 Al, the Bragg peaks of both Mg and Mg\({}_{17}\)Al\({}_{12}\) were observed. For Mg-10 Zn, Mg-20 Zn, and Mg-30 Zn, the Bragg peaks of both Mg and Mg\({}_{2}\)Zn\({}_{3}\) were observed. The presence of weak MgO diffraction peaks in pure Mg may be attributed to slight oxidation during the experimental operation, specifically when the Mg metal was briefly exposed to air during turning. No other impurities or oxides, such as MgO, were observed in the XRD patterns of Mg-Al and Mg-Zn alloys, indicating that both materials were not oxidized during the initial preparation process. No shift in the Bragg peaks of Mg was observed in the XRD patterns of the aforementioned materials. Figure 3 displays the SEM and EDS images of as-cast pure Mg. As observed in Figure 3, the machined magnesium milling surface exhibits a stepped appearance accompanied by locally torn gaps. This phenomenon arises due to the poor plasticity of metallic magnesium during the machining process. Additionally, trace amounts of oxygen elements are observed in the EDS images, consistent with the previous XRD patterns. The formation of a trace amount of MgO passivation film on the Mg matrix surface due to slight oxidation does not significantly affect the hydrogen production performance of magnesium-based metal hydrolysis under high-temperature conditions. Figure 1: Schematic diagram of hydrogen production plant by high temperature hydrolysis of Mg, Mg-Al and Mg-Zn. Figure 2: The XRD pattern of the initial material of (**a**) pure-Mg. XRD patterns of the initial materials of (**b**) Mg-10 Al, Mg-20 Al, and Mg-30 Al alloys. XRD patterns of the initial materials of (**c**) Mg-10 Zn, Mg-20 Zn, and Mg-30 Zn alloys. As observed in Figure 4a-c, the as-cast Mg-10 Al, Mg-20 Al, and Mg-30 Al binary alloys primarily consist of a Mg matrix and a secondarily precipitated Mg17 Al12 microstructure distributed within it. The corresponding microstructural details of the secondarily precipitated Mg17 Al12 are shown in the locally enlarged images. With increasing aluminum content, when the Al content is only 10%, the secondarily precipitated Mg17 Al12 is dispersed in a dot-like and partially lamellar form within the magnesium matrix. When the Al content rises to 20%, the secondarily precipitated Mg17 Al12 exhibits a continuous lamellar distribution, with a small amount also observed in a dot-like form. When the aluminum content increases to 30%, the secondarily precipitated Mg17 Al12 forms a continuous lamellar network distribution, nearly covering the entire surface of the magnesium matrix, making it difficult to observe dot-like dispersed Mg17 Al12 phases at this point. The EDS spectra of magnesium and aluminum elements reflect the distribution of the Mg17 Al12 phase. Combined with the XRD patterns shown in Figure 2b, it further confirms that the materials were not oxidized during the initial machining process, and no MgO was formed. With increasing aluminum content, there is a clear distinction between the dot-like, lamellar, and lamellar network secondarily precipitated Mg17 Al12 phases and the magnesium matrix phase. Figure 4: The SEM and EDS images of the initial material of (**a**) Mg-10 Al, (**b**) Mg-20 Al, and (**c**) Mg-30 Al. Figure 3: The SEM and EDS spectra of the initial material of pure-Mg.  
As observed in Figure 5a-c, the as-cast Mg-10 Zn, Mg-20 Zn, and Mg-30 Zn binary alloys primarily consist of a magnesium matrix and a secondarily precipitated Mg;Zn\({}_{3}\) microstructure distributed within it. With increasing zinc content, changes are observed.