ABSTRACT

The mechanical strength of pure aluminum matrix can be greatly enhanced by adding a small amount of nickel-coated carbon nanotubes (NiCNTs), where the nickel coating helps to the uniform dispersion of carbon nanotubes (CNTs) within the aluminum matrix through decreasing density difference and avoiding CNTs agglomeration. The yield strength of pure aluminum can be increased by 33.3% with 1% weight fraction of NiCNTs. This strengthening effect is caused by three mechanisms: Orowan looping, load bearing, and thermal expansion mismatch which are studied by both finite-element method and analytical method. A series of finite-element analyses using a representative volume element (RVE) method are conducted considering influences of CNTs aspect ratios, volume fraction of hardened zone, and the hardened plastic strain of hardened zone. The results show that the aspect ratio of CNTs is very important in the strengthening of CNT-reinforced composites, and the yield stress increases with increasing aspect ratio. A set of parameters for analytical solutions are optimized that can well describe and accurately predict the experimental data. Both the finite-element analysis and analytical solution are well correlated with the experimental results for Al/NiCNT composites with different weight fractions of CNTs.

摘要

纯铝基体的机械强度可以通过添加少量的镍包覆碳纳米管（NiCNTs）来大大提高，其中镍涂层通过减小密度差异和减少密度差异有助于碳纳米管（CNTs）在铝基体中的均匀分散。避免碳纳米管聚集。NiCNTs重量分数为1%时，纯铝的屈服强度可提高33.3%。这种强化效果是由三种机制引起的：Orowan 循环、承载和热膨胀失配，这些机制通过有限元方法和解析方法进行了研究。考虑到碳纳米管纵横比、硬化区的体积分数和硬化区的硬化塑性应变的影响，使用代表性体积元 (RVE) 方法进行了一系列有限元分析。结果表明，碳纳米管的纵横比对碳纳米管增强复合材料的强化非常重要，屈服应力随着纵横比的增加而增加。优化了一组解析解参数，可以很好地描述和准确预测实验数据。有限元分析和解析解都与具有不同碳纳米管重量分数的铝/镍碳纳米管复合材料的实验结果密切相关。