Analysis and Discussion on the Room Temperature Microstructure and Properties of High Content Mixed Rare-Earth As-Cast AZ61 Magnesium Alloy

• Published in: Strength of materials 2023-11, Vol.55 (6), p.1215-1227
• Main Authors: Cao, F. H., Zhang, Y., Chen, Y., Jiang, M. G., Zhou, J. L., He, Y.
• Format: Article
• Language: English
• Subjects: Cerium; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Decomposition; Fracture mechanics; Magnesium alloys; Magnesium base alloys; Magnesium castings; Materials Science; Mechanical properties; Microstructure; Optical microscopy; Phases; Quasicrystals; Rare earth elements; Room temperature; Solid Mechanics; Specialty metals industry; Tensile strength; Zinc
• ISSN: 0039-2316; 1573-9325
• DOI: 10.1007/s11223-024-00612-0

This paper systematically analyzed and discussed the microstructure and mechanical properties of as-cast AZ61 magnesium alloy with rare-earth content of 1.0~4.0 wt.% by optical microscopy, SEM, EDS, and XRD. The results indicate that in addition to the obvious distribution of skeletal β -Mg 17 Al 12 phase, a small amount of Mg 32 (Al, Zn) 49 quasicrystal phase is distributed in as-cast AZ61 alloy. With the addition of rare-earth content, the skeletal β -Mg 17 Al 12 phase dendrites in the as-cast AZ61 magnesium alloy matrix are decomposed obviously. The dendrite decomposition is more serious with increased Rare-earth content, and the quasicrystal Mg 32 (Al, Zn) 49 disappears. When the rare-earth content is 1%Ce~2%Ce, the alloy mainly consists of needle-like, dot-like, or clustered Al 4 Ce and Al 8 Mn 4 Ce phases with a small amount of Al 4 La. When 2.8%Ce+1.2%Nd mixed rare-earth was added, the Al 8 Mn 4 Ce phase was not found in the alloy but mainly composed of Al 3 Nd and Al 4 Ce rare-earth phases. These rare-earth phases were radiative needle-like, willow leaf-like, rod-like, spot-like, layer-like, and a little irregular block. The as-cast AEZ641(2.8 wt.% Ce+1.2 wt.% Nd) magnesium alloy has the best comprehensive performance, and the yield strength is 2% higher than the as-cast AZ61 alloy. Its tensile strength, hardness, and elongation are similar to as-cast AZ61 alloy. The fracture mechanism of as-cast AZ61 + xRE is mainly a cleavage-type brittle fracture.