石墨烯纳米片/AZ91镁基复合材料的显微组织与力学性能

摘要

采用铸造工艺制备了石墨烯纳米片(GNPs)增强的AZ91镁基复合材料,测试了复合材料的力学性能,并利用光学显微镜、X射线衍射仪、透射电子显微镜、扫描电子显微镜和能谱仪对复合材料的微观组织、界面结合和断口形貌进行了表征和分析,讨论了复合材料的强化机理.结果表明:石墨烯纳米片可有效细化镁基体的晶粒组织,在添加少量石墨烯纳米片时(0.1％),复合材料的屈服强度、延伸率和显微硬度分别为(164±5)MPa、(7.7±0.1)％和(74.2±2)HV,比基体分别提高了37.8％、13.2％和24.7％.GNPs与镁基体形成了强界面结合,这更有利于发挥应力转移强化、细晶强化等作用,提高镁合金强度、塑性等力学性能.%Graphene nanosheets (GNPs)reinforced AZ91 alloy matrix composite was fabricated by a casting method.The me-chanical properties of the composite were tested.The microstructure,interfacial bonding structure and fractographs of the as-cast composite were characterized and analyzed via optical microscopy,X-ray diffraction (XRD),transmission electron microscopy (TEM)and scanning electron microscopy (SEM)equipped with energy-dispersive spectrometer (EDS).The strengthening mecha-nism of GNPs/AZ91 composite was discussed in detail.The results showed that GNPs can effectively refine the grain sized of AZ91 alloy.The yield strength,elongation and microhardness of AZ91-0.1GNPs composite was (164±5)MPa,(7.7±0.1)％ and (74.2±2)HV,increasing by 37.8％,13.2％ and 24.7％,respectively,compared to that of as-cast AZ91 alloy.A strong interfacial bonding between GNPs and the matrix ofα-Mg have been formed,which is beneficial to the fine-grain strengthening,stress transfer strengthening and so on,resulting in a significant improvement in the tensile strength,ductility and other mechanical properties of magnesium alloy.