Effect of graphene content on the microstructure and mechanical properties of graphene-reinforced Al-15Si-4Cu-Mg matrix composites
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摘要: 低温球磨分散结合真空热压烧结工艺制备了石墨烯增强的Al-15Si-4Cu-Mg基复合材料.采用扫描电镜、X射线衍射、能谱分析和透射电镜表征了复合材料微观结构，通过抗拉强度和硬度测试，研究了石墨烯添加量对石墨烯/Al-15Si-4Cu-Mg复合材料微观组织和力学性能的影响.结果表明：当石墨烯质量分数分别为0.4%和0.8%，石墨烯沿基体晶界均匀分布，钉扎晶界，石墨烯与Al-15Si-4Cu-Mg基体界面结合良好，初晶β-Si、Mg2Si和Al2Cu相弥散分布于基体中.当石墨烯质量分数上升至1%，石墨烯分散困难，过量石墨烯富集于晶粒边界处，诱发脆性鱼骨状Al4Cu2Mg8Si7相沿晶界析出.当石墨烯质量分数为0.8%时，石墨烯/Al-15Si-4Cu-Mg复合材料的拉伸强度和硬度分别达到321 MPa和HV 98，相比纯Al-15Si-4Cu-Mg复合材料分别提高了19.3%和46.2%；当石墨烯质量分数为0.4%时，复合材料的屈服强度高达221 MPa，硬度和塑性亦获得明显改善.
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关键词:
- 石墨烯/Al-15Si-4Cu-Mg复合材料 /
- 石墨烯 /
- 微观组织 /
- 力学性能 /
- 硬度
Abstract: A graphene-nanoflakes (GNFs)-reinforced GNFs/Al-15Si-4Cu-Mg composite was prepared through low-temperature ball-grinder milling and vacuum hot-press sintering. The influences of the GNFs mass content on the microstructural and mechanical properties of the GNFs/Al-15Si-4Cu-Mg composite were investigated via scanning electron microscope, X-ray diffraction, energy disperse spectroscopy, and transmission electron microscope. Meanwhile, tensile strength and micro-hardness tests were conducted. The corresponding result show that for the specimens with 0.4% and 0.8% (mass fraction) GNFs in mass fraction, the nanoflakes are concentrated on the border of the aluminum alloy grain and played a major role in restraining the matrix grain expansion and avoiding crystal particle coarsening. Moreover, the interface bonding between the GNFs and Al-15Si-4Cu-Mg matrix is strong. There are primary β-Si particles, Mg2Si, and Al2Cu-phase precipitated dispersedly throughout the aluminum matrix. The strong interface bonding between the GNFs and Al-15Si-4Cu-Mg matrix leads to the effective impeding of the dislocation slippage and the improvement in the properties of the GNFs/Al-15Si-4Cu-Mg composites. With the addition of the 1.0% GNFs, it is difficult for the GNFs to disperse but easy for them to cluster together to form black impurities on the grain border, inducing brittle Al4Cu2Mg8Si7 phase precipitation along the aluminum alloy grain boundary. As the content of GNFs increases, the composite tensile strength first increases and then decreases. With an addition of 0.8% GNFs, the composite exhibited higher strength and micro- hardness (321 MPa of tensile strength and HV 98 of micro hardness), with the strength and micro-hardness increasing by 19.3%和46.2%, respectively, compared with the pure Al-15Si-4Cu-Mg composite without added GNFs. With the addition of 0.4% GNFs, the yield strength reaches 221 MPa; however, the micro-hardness and ductility (elongation rate) are enhanced. The combined properties of the GNFs/Al-15Si-4Cu-Mg composite obtained are clearly improved.-
Key words:
- GNFs/Al-15Si-4Cu-Mg composites /
- graphene nanoflakes /
- morphology /
- mechanical properties /
- hardness
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