挤压和时效态Mg-Y-Cu合金的显微组织和力学性能  

Microstructure and mechanical properties of extruded and aged Mg-Y-Cu alloy

作　　者：毕广利[1,2] 张妞明 姜静 陈体军[1,2] 蒋春宏 李元东[1,2] BI Guang-li;ZHANG Niu-ming;JIANG Jing;CHEN Ti-jun;JIANG Chun-hong;LI Yuan-dong(State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,Lanzhou University of Technology,Lanzhou 730050,China;School of Materials Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China;Lanshi Foundry Co.,Ltd.,Lanzhou 730050,China)

机构地区：[1]兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室,兰州730050 [2]兰州理工大学材料科学与工程学院,兰州730050 [3]兰石铸造有限公司,兰州730050

出　　处：《中国有色金属学报》2022年第3期731-740,共10页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(51961021,52001152)。

摘　　要：采用光学显微镜(OM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)、维氏硬度计和万能试验机,研究了挤压和时效态Mg-6.8Y-2.5Cu(质量分数,%)合金的显微组织和力学性能。结果表明:挤压合金主要由α-Mg基体、沿挤压方向分布的片层状和块状18R类型的长周期堆垛有序相(18R-LPSO)、Mg_(2)Cu相以及晶粒内细小条纹状的14H-LPSO相组成。180℃等温时效后,亚稳18R-LPSO相分解,晶内析出新的14H-LPSO相。合金在58 h和130 h处分别出现两个硬度峰值,其硬度值分别为69.2 HV和70.2 HV。第一个时效峰的出现主要源于大量18R-LPSO相和部分14H-LPSO相的析出。第二个时效峰的出现源于晶粒内部高体积分数14H-LPSO相的析出。拉伸测试结果表明:时效130 h的挤压合金在室温下具有最高的极限抗拉强度(276.8 MPa)和伸长率(25.9%)。合金高的抗拉强度主要归因于14H-LPSO相的析出强化及18R-LPSO相的弥散强化。The microstructure and mechanical properties of the extruded and aged Mg-6.8Y-2.5Cu alloys were investigated by optical microscope(OM),scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray diffractometer(XRD),Vickers micro-hardness tester and tensile testing machine.The results show that the extruded alloy is mainly composed ofα-Mg matrix,lamellar and block 18R type long-period stacking ordered(18R-LPSO)phase distributes along the extrusion direction,Mg_(2)Cu phase and the fine striped 14H-LPSO phase in the grain interior.During the 180℃isothermal aging process,parts of metastable 18R-LPSO phases occurrs to dissolve and the new 14H-LPSO phase precipitated in Mg matrix.Two hardness peaks of the extruded alloy appear at 58 h and 130 h,and hardness values are 69.2 HV and 70.2 HV,respectively.The first ageing peak arises from a great number of 18R-LPSO phases and small amounts of 14H-LPSO phases.The second aging peak originates from the precipitation of a large number of 14H-LPSO phases in the grain interior.The tensile test results show that the extruded alloy aged for 130 h exhibits the highest ultimate tensile strength(276.8 MPa)and elongation(25.9%)at room temperature.The good tensile strengths of the alloy are mainly attributed to the precipitation strengthening of the 14H-LPSO phase and the dispersion strengthening of the 18R-LPSO phase.

关 键 词：挤压Mg-Y-Cu合金 LPSO相 显微组织 力学性能 

分 类 号：TG146.2[一般工业技术—材料科学与工程]