放电等离子体烧结制备Mg85Zn6Y9颗粒增强Mg-9Al-1Zn复合材料组织与力学性能

采用高能球磨法和放电等离子体烧结（SPS）技术，以包含100%长周期堆垛有序结构（LPSO）相Mg₈₅Zn₆Y₉镁合金为原料，通过将其球磨成纳米晶颗粒后与Mg-9Al-1Zn（AZ91）镁合金雾化颗粒进行机械混合，并在350℃烧结温度下成功制备出不同质量分数（0~30wt%）的LPSO相Mg₈₅Zn₆Y₉颗粒增强AZ91复合材料（Mg₈₅Zn₆Y₉/AZ91）。采用光学显微镜（OM）、SEM及TEM对Mg₈₅Zn₆Y₉/AZ91复合材料的微观组织结构进行表征；采用XRD分析其固溶处理前后的相转变；与此同时对复合材料进行显微硬度与压缩试验，综合研究其微观组织与力学性能的关系。相关结果表明，Mg₈₅Zn₆Y₉颗粒经3 h高能球磨后颗粒尺寸显著减小，硬度随晶粒细化而提升。Mg₈₅Zn₆Y₉增强颗粒主要分布在AZ91基体颗粒边界处，随着Mg₈₅Zn₆Y₉质量分数的增加，增强相颗粒有相互结合成连续网格状趋势。增强颗粒与基体界面处未见明显过渡层，基体界面处的β相经400℃×24 h固溶处理后进入基体，部分增强颗粒亦转变为Mg相。本实验条件下制备的最佳性能的20wt% Mg₈₅Zn₆Y₉/AZ91复合材料经固溶处理后的室温屈服强度从200 MPa转变为230 MPa，屈服强度均较未添加Mg₈₅Zn₆Y₉的AZ91镁合金有较大的提高。

Microstructural evolution and mechanical properties of Mg85Zn6Y9 powder reinforced Mg-9Al-1Zn composites prepared by spark plasma sintering

The composition of as-cast Mg₈₅Zn₆Y₉ alloy with almost 100% long period stacking ordered structure (LPSO) phase was milled into nanocrystalline powder by the high energy ball milling, then was mechanical blended with atomized Mg-9Al-1Zn(AZ91) powder. The Mg₈₅Zn₆Y₉/AZ91 composites with the mass fraction of Mg₈₅Zn₆Y₉ powder from 0wt% to 30wt% were prepared by spark plasma sintering (SPS) at 350℃. The microstructure of Mg₈₅Zn₆Y₉/AZ91 composites was characterized with optical microscope (OM), SEM and TEM; XRD was used to analyze phase transition of the composite before and after solid solution treatment; microhardness and compression test were also carried out to study the mechanical properties of the composites. The results show that the Mg₈₅Zn₆Y₉ powder's grain size decreases and the microhardness of the Mg₈₅Zn₆Y₉ powder increases obviously after 3 h high energy ball milling. In addition, the Mg₈₅Zn₆Y₉ powder is mainly distributed at the boundaries of the AZ91 matrix powder. With more addition of Mg₈₅Zn₆Y₉ powder, the Mg₈₅Zn₆Y₉ powders likely combine with each other to form a continuous grid. Moreover, there is no obvious transition layer at the interface between Mg₈₅Zn₆Y₉ powder and matrix. After solid solution treatment at 400℃ for 24 h, β phase is dissolved into the matrix and LPSO phase is disappeared gradually. The compressive yield strength at room temperature of the prepared 20wt% Mg₈₅Zn₆Y₉/AZ91 composite with best performance changes from 200 MPa to 230 MPa, which the yield strength is significantly enhanced compared with AZ91 without Mg₈₅Zn₆Y₉ powder addition.