High strength Mg-Zn-Y alloys reinforced synergistically by Mg12ZnY phase and Mg3Zn3Y2 particle

Publication date: 5 May 2017
Source:Journal of Alloys and Compounds, Volume 703
Author(s): J. Zhu, X.H. Chen, L. Wang, W.Y. Wang, Z.K. Liu, J.X. Liu, X.D. Hui
Eight Mg100-x-yZnxYy (at.%, x = 2–7.2, y = 4–7) alloys with atomic ratios of Y/Zn = 0.75–2 were designed and prepared by rapidly solidified powder metallurgy technology. The atomized powders with the Y/Zn atomic ratios larger than 1 contain α-Mg dendrite and network-like X-Mg12ZnY compound, but those with the Y/Zn atomic ratios of 1 and 0.75 have W-Mg3Zn3Y2 particle besides the above two phases. After hot extrusion, network-like Mg12ZnY phase was changed into acicular and plate-like shape. These as-extruded alloys exhibit excellent mechanical properties at room and elevated temperature. Especially, the ultimate tensile strength of as-extruded Mg86Zn7Y7 alloy reaches up to 541 MPa at room temperature and 297 MPa at 250 °C. HRTEM study reveals that Mg12ZnY phase is composed of 18R LPSO structures. These sub-micrometer Mg3Zn3Y2 particles bring about dispersion strengthening to Mg12ZnY phases, resulting in a synergistic strengthening of Mg12ZnY phase and Mg3Zn3Y2 particle in the alloy which has the Y/Zn atomic ratio equal to or larger than 1. Therefore, the excellent mechanical properties of Mg86Zn7Y7 alloy are attributed to the second phase strengthening of LPSO phase and synergistic strengthening of Mg12ZnY phase and Mg3Zn3Y2 particle.



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