Fabrication of high-strength Mg-Y-Sm-Zn-Zr alloy by conventional hot extrusion and aging

A high-strength Mg-7Y-5Sm-0.5Zn-0.3Zr alloy was developed successfully by hot extrusion and subsequent aging treatment. The results showed that the as-solutionized alloy mainly contained α-Mg matrix and 14H LPSO phase distributed at grain boundaries. Lamellar LPSO and γ′ phases were dynamically precipitated during hot extrusion and retained after artificial aging treatment at 200°C. After peak-aged treatment, the alloy exhibited excellent mechanical properties with ultimate tensile strength of 465 MPa, 0.2% proof stress of 413 MPa and elongation to failure of 6.5% at room temperature. The high yield strength was attributed to the combined action of 14H-LPSO phase, basal γ′ precipitates and dense distribution of β′ precipitates at prismatic plane.