Targeted Mg-Y-Zn alloy design based on revised LPSO phase compositions and equilibria

Monday, September 12, 2022: 4:00 PM
Convention Center: 272 (Ernest N. Morial Convention Center)
Prof. Rainer Schmid-Fetzer , Clausthal University of Technology, Clausthal-Zellerfeld, Germany
Dr. Yongxin Ruan , University of Science and Technology Beijing, Beijing, China
Prof. Changrong Li , University of Science and Technology Beijing, Beijing, China
Dr. Xiaopan Wu , University of Science and Technology Beijing, Beijing, China
Prof. Yuping Ren , Northeastern University, Shenyang, China
Prof. Cuiping Guo , University of Science and Technology Beijing, Beijing, China
Prof. Zhenmin Du , University of Science and Technology Beijing, Beijing, China
The properties of Mg alloys may be significantly enhanced due to formation of long-period stacking ordered (LPSO) phases. The Mg-Y-Zn alloy system is most important since different LPSO structures (14H, 18R and 10H) together with other intermetallics may be formed in such complex Mg-rich alloys. The precise knowledge of phase equilibria and transformations in Mg-Y-Zn alloys is indispensable for targeted alloy design. This work demonstrates that the currently known LPSO phase compositions as well as their equilibria need significant revision. The experimental work presented comprises dedicated characterization (XRD, SEM, TEM, HAADF-STEM) of Mg-rich alloys annealed at 400°C and 500°C. Based on that knowledge and thermodynamic Mg-Y-Zn phase diagram calculations the alloy composition and the heat-treatment temperature of a Mg86Y8Zn6 (at.%) alloy with sole LPSO structures 18R and 14H was successfully tailored. A narrow composition and temperature window to avoid adverse phases is indicated.
See more of: Fundamental and applications-oriented experimental observations
See more of: PSDK XV: Phase Stability and Diffusion Kinetics