An elevated temperature Mg–Dy–Zn alloy with long period stacking ordered phase by extrusion

A Mg–2Dy–0.5Zn (at.%) alloy was prepared by casting, heat treating at 525 °C for 10 h, extruding at 360 °C and ageing at 180 °C for 90 h. Microstructure characterization revealed that this alloy consists of the fine-grained α-Mg matrix composed nearly of the 14H long period stacking ordered (LPSO) phase and a small amount of (Mg, Zn)xDy precipitations. Tensile tests showed that the yield and ultimate tensile strengths of this alloy can reach 245 MPa and 260 MPa at 300 °C, which are only slightly lower than those at room temperature (287 MPa and 321 MPa), the elongation of this alloy is 36% at 300 °C, which is far higher than that at room temperature (11.6%). The high volume fraction of the 14H LPSO phase in the fine-grained α-Mg grains and the high thermal stability of the microstructure during elevated temperature deformation are responsible for the excellent elevated temperature properties observed for this alloy.