(重庆大学 材料科学与工程学院，机械传动国家重点实验室，重庆 40044)
摘 要: 通过活性钨极氩弧焊接将石墨烯纳米片溶入AZ31镁合金中，制得石墨烯/AZ31镁合金复合焊接接头。研究石墨烯加入量对复合焊接接头组织和性能的影响。结果表明：石墨烯纳米片在Marangoni逆流的运载和电磁力的搅拌作用下，均匀分布在AZ31镁合金基体中。均匀分散的石墨烯纳米片有效地细化镁合金的晶粒组织，并显著提高其接头的力学性能。所有试样中，4#石墨烯/AZ31镁合金复合接头的晶粒尺寸最小(约19.8 μm)，力学性能最优，其极限拉伸强度和显微硬度为198 MPa和68.9 HV，约为未添加石墨烯纳米片AZ31镁合金接头的190.4%和130%，同时，接头的韧性也达到最佳。因此，石墨烯纳米片的添加量在1.41%左右时，能获得性能最好的石墨烯/AZ31镁合金复合接头。
关键字: 石墨烯纳米片；AZ31镁合金；活性钨极氩弧焊接；微观组织；力学性能
（State Key Laboratory of Mechanical Transmission, College of Material Science and Engineering, Chongqing University, Chongqing 400044, China）
Abstract:The graphene nanosheets/AZ31 magnesium alloy composite joints were fabricated by introducing graphene nanosheets into magnesium alloy through activating flux tungsten inert gas welding. The effects of graphene addition amount on microstructure and properties of composite joints were studied. The results show that graphene nanosheets evenly disperse in magnesium alloy matrix due to the combined effect of Marangoni convection and electromagnetic forces. The uniformly dispersed graphene nanosheets refine matrix crystals and enhance mechanical property of the composite joints. The minimum grain size (about 19.8 μm) and optimum of mechanical properties of sample 4# is obtained. The ultra-tensile strength and microhardness of the composite joints reach to 198 MPa and 68.9HV, about 190.4% and 130% of those of the joints without graphene nanosheets, respectively. Simultaneously, the toughness is also the best. Therefore, the grapheme nanosheets/AZ31 magnesium alloy composite joints with the best performance can be obtained when graphene addition amount is about 1.41%.
Key words: graphene nanaosheet; AZ31 magnesium alloy; activating flux tungsten inert gas welding; microstructure; mechanical property
