为获得优异力学性能的复合材料,选用石墨烯作为增强体.本文采用粉末冶金方法,经高能球磨法、冷压、烧结、热压和热挤压制备了AZ31镁合金及石墨烯(GNPs)增强AZ31镁基复合材料棒状试样,通过光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射(XRD)和室温拉伸、压缩表征了该材料的组织和力学性能.结果表明:制备的复合材料及基体中生成了Mg17Al12和MgO,加入GNPs后复合材料的屈服强度与维氏硬度都优于基体材料;加入GNPs质量分数为0.5％和1.0％的GNPs复合材料分别比基体屈服强度增加13.2％和14.2％(258和259 MPa),显微维氏硬度分别增加11.4％和14.3％(78和80 HV),主要的强化机制为载荷转移强化、奥罗万强化、热错配强化,但材料的拉伸延伸率分别降低到3.9％和4.3％,比基体分别降低了38％和32％,材料的致密度分别为99.6％、98.5％、97.8％,随着GNPs的增加,致密度降低;GNPs的加入未改变材料的断裂方式,材料的断裂方式均主要为脆性断裂;GNPs的添加使复合材料的基面{0002}织构弱化,从而降低材料的屈服不对称性.%In order to obtain composite material with excellent mechanical properties, graphene nanoplatelets (GNPs) was used as reinforcement. The research adopted the powder metallurgy method. AZ31 magnesium alloy and GNPs-reinforced AZ31 magnesium matrix composite rod sample were prepared by high-energy ball mill, cold pressing, sintering, hot pressing, and hot extrusion. The microstructure and mechanical properties of the materials were characterized by optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), and room temperature tensile and compression. The experimental results show that Mg17Al12 and MgO were generated from the prepared material and the yield strength and Vickers hardness of the composites with GNPs were better than those without GNPs, whose yield strength increased by 13.2％ and 14.2％ (which is 258 MPa and 259 MPa) and micro Vickers hardness increased by 11.4％ and 14.3％ (which is 78 HV and 80 HV), respectively. The main strengthening mechanisms are load transfer enhancement, Orowan reinforcement, and thermal mismatch enhancement. However, the tensile elongation of the materials δ decreased to 3.9％ and 4.3％, which are 38％ and 32％ lower than those of the base, respectively. As the density of the material decreases with the increase of GNPs, the density decreased to 99.6％, 98.5％, and 97.8％, respectively. The addition of GNPs did not change the fracture mode of the materials, which is mainly brittle fracture. The addition of GNPs weakened the texture of the composite materials' base surface {0002}, thereby reducing the yield asymmetry of the material.
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