Phase Equilibria of the Mg-Zn-Sm System in Mg-Rich Corner at 320 °C and 400 °C
To clarify the controversy regarding the phase equilibria in the Mg-rich corner of the Mg-Zn-Sm system, alloys annealed at 320 °C and 400 °C were employed to determine the phase constitution, composition and crystal structure by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmi...
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MDPI AG
2022-09-01
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| author | Tian Yin Zheng Ma Hongcan Chen Qun Luo Jieyu Zhang Guangxin Wu |
| author_facet | Tian Yin Zheng Ma Hongcan Chen Qun Luo Jieyu Zhang Guangxin Wu |
| author_sort | Tian Yin |
| collection | DOAJ |
| description | To clarify the controversy regarding the phase equilibria in the Mg-rich corner of the Mg-Zn-Sm system, alloys annealed at 320 °C and 400 °C were employed to determine the phase constitution, composition and crystal structure by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The maximum solubility of Zn in Mg<sub>3</sub>Sm was measured to be 49.2 at.% at 400 °C. The Y phase (Mg<sub>62</sub>Zn<sub>31</sub>Sm<sub>7</sub>), only observed in the as-cast alloys, was determined to have an orthorhombic structure with lattice parameters of a = 10.20 Å, b = 11.26 Å and c = 9.64 Å by TEM. The hexagonal compound μ<sub>7</sub>, identified with lattice parameters of a = 34.62 Å and c = 8.94 Å, was detected during the transformation of the Y phase to the Z phase in the alloys located in the (Mg) + Mg<sub>3</sub>Sm + Z three-phase region. The phase equilibria (Mg) + Mg<sub>41</sub>Sm<sub>5</sub> + Mg<sub>3</sub>Sm, Mg + Mg<sub>3</sub>Sm + Z, (Mg) + Z + liquid and Mg<sub>2</sub>Zn<sub>3</sub> + Z + liquid at 400 °C are confirmed, and the three-phase region (Mg) + Z + MgZn exists in the Mg-Zn side at 320 °C. Subsequently, a self-consistent thermodynamic description was obtained based on the experimental data. Meanwhile, solidification simulation of Y phase formation was conducted by suppressing the stale Z phase, which can reasonably explain the as-cast microstructure of alloys in the Mg-rich corner. The thermodynamic database would be helpful for the further development of Mg-Zn-Sm alloys. |
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| spelling | doaj.art-e5fc355e2c6b493e9e403f95f3074ade2023-11-24T01:16:49ZengMDPI AGMetals2075-47012022-09-011210155310.3390/met12101553Phase Equilibria of the Mg-Zn-Sm System in Mg-Rich Corner at 320 °C and 400 °CTian Yin0Zheng Ma1Hongcan Chen2Qun Luo3Jieyu Zhang4Guangxin Wu5State Key Laboratory of Advanced Special Steel, Shanghai Key Laboratory of Advanced Ferrometallurgy, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, ChinaState Key Laboratory of Advanced Special Steel, Shanghai Key Laboratory of Advanced Ferrometallurgy, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, ChinaState Key Laboratory of Advanced Special Steel, Shanghai Key Laboratory of Advanced Ferrometallurgy, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, ChinaState Key Laboratory of Advanced Special Steel, Shanghai Key Laboratory of Advanced Ferrometallurgy, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, ChinaState Key Laboratory of Advanced Special Steel, Shanghai Key Laboratory of Advanced Ferrometallurgy, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, ChinaState Key Laboratory of Advanced Special Steel, Shanghai Key Laboratory of Advanced Ferrometallurgy, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, ChinaTo clarify the controversy regarding the phase equilibria in the Mg-rich corner of the Mg-Zn-Sm system, alloys annealed at 320 °C and 400 °C were employed to determine the phase constitution, composition and crystal structure by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The maximum solubility of Zn in Mg<sub>3</sub>Sm was measured to be 49.2 at.% at 400 °C. The Y phase (Mg<sub>62</sub>Zn<sub>31</sub>Sm<sub>7</sub>), only observed in the as-cast alloys, was determined to have an orthorhombic structure with lattice parameters of a = 10.20 Å, b = 11.26 Å and c = 9.64 Å by TEM. The hexagonal compound μ<sub>7</sub>, identified with lattice parameters of a = 34.62 Å and c = 8.94 Å, was detected during the transformation of the Y phase to the Z phase in the alloys located in the (Mg) + Mg<sub>3</sub>Sm + Z three-phase region. The phase equilibria (Mg) + Mg<sub>41</sub>Sm<sub>5</sub> + Mg<sub>3</sub>Sm, Mg + Mg<sub>3</sub>Sm + Z, (Mg) + Z + liquid and Mg<sub>2</sub>Zn<sub>3</sub> + Z + liquid at 400 °C are confirmed, and the three-phase region (Mg) + Z + MgZn exists in the Mg-Zn side at 320 °C. Subsequently, a self-consistent thermodynamic description was obtained based on the experimental data. Meanwhile, solidification simulation of Y phase formation was conducted by suppressing the stale Z phase, which can reasonably explain the as-cast microstructure of alloys in the Mg-rich corner. The thermodynamic database would be helpful for the further development of Mg-Zn-Sm alloys.https://www.mdpi.com/2075-4701/12/10/1553Mg-Zn-Sm alloyphase equilibriaternary compoundsCALPHAD |
| spellingShingle | Tian Yin Zheng Ma Hongcan Chen Qun Luo Jieyu Zhang Guangxin Wu Phase Equilibria of the Mg-Zn-Sm System in Mg-Rich Corner at 320 °C and 400 °C Metals Mg-Zn-Sm alloy phase equilibria ternary compounds CALPHAD |
| title | Phase Equilibria of the Mg-Zn-Sm System in Mg-Rich Corner at 320 °C and 400 °C |
| title_full | Phase Equilibria of the Mg-Zn-Sm System in Mg-Rich Corner at 320 °C and 400 °C |
| title_fullStr | Phase Equilibria of the Mg-Zn-Sm System in Mg-Rich Corner at 320 °C and 400 °C |
| title_full_unstemmed | Phase Equilibria of the Mg-Zn-Sm System in Mg-Rich Corner at 320 °C and 400 °C |
| title_short | Phase Equilibria of the Mg-Zn-Sm System in Mg-Rich Corner at 320 °C and 400 °C |
| title_sort | phase equilibria of the mg zn sm system in mg rich corner at 320 °c and 400 °c |
| topic | Mg-Zn-Sm alloy phase equilibria ternary compounds CALPHAD |
| url | https://www.mdpi.com/2075-4701/12/10/1553 |
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