Fabrication and characterization of GNPs and CNTs reinforced Al7075 matrix composites through the stir casting process

This study investigated the effects of adding graphene nanoplates(GNPs)and carbon nanotubes(CNTs)into the Al7075 matrix via the stir casting method on the microstructure and mechanical properties of the fabricated composites.By increasing the volume fraction of rein-forcements,the fraction of porosity increased.The X-ray diffraction results showed that the addition of reinforcements into the Al7075 changed the dominant crystal orientation from(002)to(111).Field emission scanning electron microscopy images also showed the distribution of clustered reinforcements in the matrix.Between the two reinforcements,the addition of CNTs generated a lower fraction of porosities.Through the addition of 0.52vol%GNPs into the matrix,the hardness,ultimate tensile strength and uniform elongation increased by 44%,32%,and 180%,respectively.Meanwhile,the presence of 0.71vol%CNTs in the matrix increased the hardness,tensile strength and uniform elongation by 108%,129%,and 260%,respectively.

搅拌摩擦通道挤压制备碳纳米管增强7075铝基复合材料

搅拌摩擦通道挤压是作者基于搅拌摩擦焊接和等通道转角挤压提出的一种固相状态制备金属基复合材料的新方法。采用搅拌摩擦通道挤压方法,通过添加不同体积分数的碳纳米管(CNTs)(0%、2%和4%),制备了碳纳米管增强7075铝合金基复合材料(CNTs/Al-7075)。通过光学显微镜、扫描电子显微镜和透射电子显微镜观察并分析了CNTs在Al-7075基体中的分布特征,以及复合材料的细晶组织和第二相颗粒特征。采用固溶和时效处理改善CNTs/Al-7075复合材料的组织和力学性能。结果表明,采用搅拌摩擦通道挤压方法可以制备CNTs分布均匀的CNTs/Al-7075复合材料,实现7075铝合金基体晶粒细化,通过引入CNTs增强相可获得更为细小的晶粒组织。随着CNTs体积分数增加,CNTs/Al-7075复合材料的晶粒更加细化。固溶和时效处理改善了搅拌摩擦通道挤压制备的7075铝合金和CNTs/Al-7075复合材料的第二相析出行为,使材料的显微硬度得到提高。CNTs/Al-7075复合材料的强化机制综合了细晶强化、位错强化、载荷传递和第二相强化,其中以第二相强化为主。