碳纳米管增强镁基复合材料的组织与力学性能

摘要

在Mg-1．3Mn-1．0Ce-4．0Zn合金熔体中加入质量分数为0~1．5％的碳纳米管(CNTs),采用搅拌铸造法制备了碳纳米管增强镁基复合材料,研究了复合材料的组织和力学性能,并探讨了复合材料的强韧化机制.结果表明：CNTs能细化基体合金的晶粒尺寸,改变晶粒形貌及第二相的分布特征；随着CNTs添加量增大,复合材料的室温强度、断口伸长率和硬度均呈先增大后减小的趋势；当CNTs的质量分数为0．5％时,室温强度、断后伸长率和硬度最高,分别为212．2 MPa,21．1％和55．0 HBW,较基体合金的分别增加了8．5％,37．5％和10％；复合材料的强韧化机制包括增强相强化、第二相强化和细晶强化,而晶粒细化、CNTs 的润滑作用及对裂纹的阻碍作用是复合材料塑性提高的主要原因.%The carbon nanotubes (CNTs)reinforced magnesium matrix composites were fabricated by adding 0-1.5wt% CNTs into the molten Mg-1.3Mn-1.0Ce-4.0Zn alloy using stirring casting process.Microstructure and mechanical properties of the composites were studied and toughening mechanism of the composites was also discussed.The results show that grain size of the substrate alloy was refined by CNTs.Meanwhile,the grain morphology and distribution characteristics of second phase also were changed by CNTs.With the increase of CNTs′adding contents,the room temperature strength,fracture elongation and hardness all increased firstly and then decreased.When the mass fraction of CNTs was 0.5%,the composites exhibited the highest tensile strength, fracture elongation and Brinell hardness,they were 212.2 MPa,21.1% and 55.0 HBW,respectively,they respectively increased 8.5%,37.5%,10% comparing with the matrix alloy.The strengthening mechanism of the composites was reinforcement phase strengthening, second phase strengthening and fine-grain strengthening. Meanwhile,grain refinement,CNTs lubrication and CNTs retarding crack extension were mainly contributed to the improvement on plasticity.