【摘要】 特定Zn、Y含量的Mg-Zn-Y合金能原位形成二十面体准晶增强I相（I-Mg₃Zn₆Y），但常规铸造凝固条件下形成的准晶组织粗大，难以发挥其性能优势。研究了重力铸造、挤压铸造及流变挤压铸造工艺制备的Mg-12Zn-1Y合金的组织和力学性能。结果表明，在重力铸造的合金组织中，大量粗大的I相和Mg₇Zn₃相聚集在一起。挤压铸造使I相转变为细小的层片状，且Mg₇Zn₃含量降低。对于流变挤压铸造的合金，随着制浆过程中超声功率增大，α-Mg晶粒得到较大程度的细化和球化，共晶组织间距明显减小，而随着超声功率持续增加到2 400 W时，共晶组织出现一定程度富集。当超声功率为1 600 W时，合金的力学性能最优，屈服强度、抗拉强度和伸长率分别为185 MPa、276 MPa和6.8%，相较于挤压铸造分别提高了35.0%、24.9%和142.9%。更多还原

【Abstract】 The icosahedral quasicrystal I-phase（Mg₃Zn₆Y） can be formed in the Mg-Zn-Y alloys with specific Zn and Y content, of which the microstructure in the conventional casting is usually coarse and difficult to exert performance advantages. The microstructure and mechanical properties of Mg-12Zn-1Y alloy prepared by gravity casting, squeeze casting and rheo-squeeze casting（RSC） were investiagted. The results reveal that in the gravity casting specimen, a large number of I-phase and Mg₇Zn₃ phase are gathered,while the squeeze casting process contributes to the morphology transformation of I-phase into fine lamellar, and the decrement of Mg₇Zn₃ phase. In the RSC process, with the increase of ultrasonic power applied during the stage of slurry-preparation, α-Mg grains are significantly refined and spheroidized, and the lamellar spacing of eutectic structure is obviously reduced. However, the concentration of eutectic structures appears when ultrasonic power continually is increased to 2 400 W. When the ultrasonic power is 1 600 W, the mechanical properties of the alloy are desirable, where the yield strength, tensile strength and elongation reach 185 MPa, 276 MPa and 6.8%, which are 35. 0%, 24. 9% and 142. 9% higher than those of squeeze casting ones, respectively.更多还原