碳纳米管对激光选区熔化成形Al基复合材料的影响
Effect of carbon nanotubes on Al matrix composites fabricated by selected laser melting

基于激光选区熔化（SLM）方式，通过改变扫描速度，制备不同碳纳米管（CNTs，质量分数分别为0、0.5wt%、1.0wt%、1.5wt%、2.0wt%）含量的CNTs/Al复合材料试件，探究不同CNTs含量与激光扫描速度对试件性能的影响。结果表明，CNTs含量小于1.0wt%时，分散效果较好，大部分CNTs以单根状态黏附于Al粉表面；含量大于1.0wt%时，CNTs团聚尺寸增大、数量增多。相同SLM成形工艺下，低CNTs含量的CNTs/Al复合材料试件内部孔隙较少，致密度较高；高CNTs含量的CNTs/Al复合材料试件内部孔隙逐渐增多，致密度降低。激光扫描速度为1 300 mm/s工艺下，随着CNTs质量分数的增加，CNTs/Al复合材料试件硬度呈先上升后下降趋势，在CNTs含量为1.0wt%显微硬度达到最高。CNTs/Al复合材料试件平均晶粒尺寸相对于铝合金试件更加细化，在CNTs含量大于1.0wt%时，尽管晶粒依然细化，但试件致密度降低造成显微硬度下降明显。 Based on selective laser melting (SLM) method, Al matrix composites reinforced with various mass fraction of carbon nanotubes(CNTs, mass fractions were 0, 0.5wt%, 1.0wt%, 1.5wt%, 2.0wt%, respectively) were produced by changing scanning speed. The effect of CNTs content and laser scan speed on performance of Al matrix composites was investigated. The results show that the dispersion is better and most of CNTs adhere to the surface of Al powder in a single state when the CNTs content(mass fraction)is not more than 1.0wt%, while the number and size of CNTs agglomerations are enhanced when the CNTs content exceeds 1.0wt%. Under the same SLM process condition, the number of pores in CNTs/Al composite specimens at low CNTs content is less so that relative densities are high. At high CNTs content, porosity of CNTs/Al composite specimen increases and relative densities of specimens reduce. With the CNTs content rising, hardness of CNTs/Al composite specimen increases firstly and then decreases at scanning speed of 1 300 mm/s. The micro-hardness of CNTs/Al composite specimen at the CNTs content of 1.0wt% reaches the peak. Compared with aluminum alloy specimen, CNTs/Al composite specimen shows finer grain size. The hardness of CNTs/Al composite specimen that the CNTs content is exceeding 1.0wt% decreases due to lower relative density, though grain size demonstrates the fine tendency. 国防基础科研项目（JCKY2016606C010）