An ultra-high strength and toughness as-cast Mg-10Gd-1.7Y-1Zn-0.5Zr (wt.%) alloy was prepared via special ultrasonic melt treatment, and the peak-aged (200 ℃ for 48 h) ultimate tensile strength (UTS), yield strength (YS) and elongation (EL) at room temperature reaches 430 MPa, 324 MPa, and 13.6%, respectively. The ultrasonic treatment during semi-solid conditions refines the grains and hinders the growth of the divorced eutectic phases (α-Mg + Mg₃Gd) during casting. During the solution treatment, the refined Mg₃Gd phase suppresses the formation of cubic-shaped GdY phases and block 14H long period stacking structure (14H-LPSO) phases, and further increases solute concentration in the matrix. More solute atoms promote the growth of β′ plates with an increased aspect ratio of 8:1, which can increase critical resolved shear stress (CRSS), YS and work hardening rate. It is that found the aspect ratio of β′ plates are mainly responsible for the improvement in the strength of the alloy under the same composition and heat treatment conditions.

通过特殊的超声波熔体处理制备了超高强韧性铸态Mg-10Gd-1.7Y-1Zn-0.5Zr（wt.%）合金，并对其峰值时效（200℃、48h）极限拉伸强度进行了研究。室温下的屈服强度（UTS）、屈服强度（YS）和伸长率（EL）分别达到430 MPa、324 MPa和13.6%。半固态条件下的超声波处理细化了晶粒，并阻碍了铸造过程中分离的共晶相（α-Mg + Mg ₃ Gd）的生长。在固溶处理过程中，细化的Mg ₃ Gd相抑制了立方形GdY相和块状14H长周期堆叠结构(14H-LPSO)相的形成，并进一步增加了基体中的溶质浓度。更多的溶质原子促进长宽比增加到8:1的β'板的生长，这可以增加临界分辨剪切应力（CRSS）、YS和加工硬化率。研究发现，在相同成分和热处理条件下，β′板的长径比是合金强度提高的主要原因。