二次变形对挤压Mg-6Gd-3.2Y-xZn-0.5Zr显微组织及力学性能的影响

郑梁¹，刘楚明¹，王洪海²，王松涛³，万迎春¹，王霄¹，陈志永¹

(1. 中南大学 材料科学与工程学院，湖南 长沙，410083；
2. 中国空空导弹研究院，河南 洛阳，471009；
3. 哈尔滨理工大学 机械与动力工程学院，黑龙江 哈尔滨，150080)

摘 要：采用金相显微镜、扫描电子显微镜、高分辨透射电子显微镜、X线衍射、维氏硬度计和万能拉伸试验机研究二次变形对挤压Mg-6Gd-3.2Y-xZn-0.5Zr合金板材显微组织、时效行为及力学性能的影响。研究结果表明：加入合金元素Zn后，合金中形成了块状和针状的LPSO组织，块状LPSO组织能够细化挤压态合金的晶粒，改善合金的二次成形能力，针状LPSO组织能够减小时效强化相β′，使其分布更加弥散，从而提高时效合金的拉伸力学性能；二次变形显著地改变了合金组织，使合金的晶粒沿变形方向拉长，并对时效过程产生了较大的影响，经过二次变形的合金强化相析出加快，时效峰提前，β′相尺寸更小，分布更加弥散，从而使合金获得了较高的力学性能。在LPSO组织和二次变形的共同作用下，T10态的合金C获得了最高的屈服强度和抗拉强度，分别为375 MPa和420 MPa。

关键词：二次变形；Mg-6Gd-3.2Y-xZn-0.5Zr合金；显微组织；力学性能；时效行为

Effect secondary deformation on microstructures and mechanical properties of Mg-6Gd-3.2Y-xZn-0.5Zr extruded sheet

ZHENG Liang¹, LIU Chu-ming¹, WANG Hong-hai², WANG Song-tao³, WAN Ying-chun¹, WANG Xiao¹, CHEN Zhi-Yong¹

(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. China Airborne Missile Academy, Luoyang 471009, China;
3. School of Mechanical and Power Engineering, Harbin University of Science and Technology, Harbin 150080, China)

Abstract:To investigate the effect of Zn addition and secondary deformation on microstructures, aging behavior and mechanical properties of Mg-6Gd-3.2Y-xZn-0.5Zr extruded sheets, the optical microscope (OM), scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), X-ray diffractometer (XRD), Vickers hardness tester and universal tensile test machine were used. The results show that block-shaped and acicular LPSO structures are found in the alloys containing Zn. The block-shaped LPSO structure can refine the microstructures, and improve the secondary deforming ability. The size of β′ phase can be reduced by the acicular LPSO structures and it distributes dispersively between the acicular LPSO structures. Both the block-shaped and acicular LPSO structures can improve the tensile mechanical properties of the Mg-Gd-Y-Zn-Zr alloys. The grains are extended in the deformation direction by secondary deformation. Secondary deformation can promote aging hardening behavior and advance the aging peak, and β′ phases are refined obviously and distributed dispersively. Due to LPSO structures and secondary deformation, T10 sample of alloy C shows the highest proof strength and tensile strength, which are 375 MPa and 420 MPa, respectively.

Key words:secondary deformation; Mg-6Gd-3.2Y-xZn-0.5Zr alloy; microstructures; mechanical properties; aging behavior