Mg-Zn-Y-Nd-Zr合金的显微组织、织构、力学性能

Microstructure, Texture, and Mechanical Properties of Mg-Zn-Y-Nd-Zr Alloys

摘要:

对Mg-Zn-Y-Nd-Zr合金的显微组织和力学性能进行了研究。结果表明，Nd元素的加入部分取代了W相（Mg₃Zn₃Y₂）中的Y元素，形成了新的第二相Mg₃Zn₃(Y, Nd)₂。热挤压后观察到由细小的等轴再结晶晶粒和粗大的细长未再结晶晶粒组成的典型双峰结构。Nd元素的加入促进了热挤压过程中的动态再结晶，随着Nd含量的增加，动态再结晶率增加，挤压态合金的整体织构强度减弱。Nd的加入细化了晶粒并改善了合金的力学性能。添加0.5%（质量分数）Nd时，挤压态合金表现出高强度和高塑性的良好结合：屈服强度为362 MPa，极限抗拉伸强度为404 MPa，延伸率为10.2%。时效处理后合金的抗拉伸强度进一步提高，峰值时效极限抗拉伸强度可达421 MPa。合金的高强度主要归功于超细再结晶晶粒和析出强化。

Abstract:

The microstructure and mechanical properties of Mg-Zn-Y-Nd-Zr alloys were studied in this research. Results show that the added Nd element partially replaces the Y element in the W phase (Mg₃Zn₃Y₂), forming a new secondary phase Mg₃Zn₃(Y, Nd)₂. A typical bimodal structure consisting of fine equiaxed recrystallized grains and coarse elongated unrecrystallized grains can be observed in the alloy after thermal extrusion. The Nd addition promotes the dynamic recrystallization during hot extrusion. With increasing the Nd content, the dynamic recrystallization ratio is increased, and the overall texture strength of the as-extruded alloy is weakened. The addition of Nd element refines the grains and improves the mechanical properties of Mg-Zn-Y-Zr alloy. When 0.5wt% Nd is added, the mechanical properties of as-extruded alloy show a good combination of high strength and high plasticity: the yield strength is 362 MPa, the ultimate tensile strength is 404 MPa, and the elongation is 10.2%. After aging treatment, the tensile strength of the alloy is further improved, and the ultimate tensile strength of the alloy after peak aging treatment reaches 421 MPa. The high strength of the Mg-Zn-Y-Nd-Zr alloy is mainly attributed to ultrafine recrystallized grains and precipitation strengthening.