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-Mg3Zn3Y2particle 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 Mg86Zn7Y7alloy 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 Mg3Zn3Y2particles bring about dispersion strengthening to Mg12ZnY phases, resulting in a synergistic strengthening of Mg12ZnY phase and Mg3Zn3Y2particle in the alloy which has the Y/Zn atomic ratio equal to or larger than 1. Therefore, the excellent mechanical properties of Mg86Zn7Y7alloy are attributed to the second phase strengthening of LPSO phase and synergistic strengthening of Mg12ZnY phase and Mg3Zn3Y2particle.
All Science Journal Classification (ASJC) codes
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry