Preparation and mechanical properties of CNTs-AlSi10Mg composite fabricated via selective laser melting

Selective laser melting（SLM）exhibits unique advantages in the fabrication of micro- and nano-particle reinforced metal matrix composites. Here, we studied the effect of scan speed on the microstructures and mechanical properties of carbon nanotubes (CNTs) reinforced AlSi10Mg composites printed by SLM. To investigate the effects of CNTs on SLM parts, single track scans, single layer scans and test parts of 1 wt%CNTs/AlSi10Mg were created via SLM. The results indicated that as the scan speed increased, the width of the scan line generally decreased and the height of the scan line generally increased. The mechanical properties of the test parts increased at first but then decreased with increasing scan speed. A laser scan speed of 1300 mm/s produced test parts with the highest mechanical properties: the relative density, hardness and tensile strength were 98.53%, 143.33 HV and 499 MPa, respectively. The hardness increased by approximately 10%, and the tensile strength increased by approximately 20% compared to those values exhibited by the unreinforced AlSi10Mg. The CNTs were detected in the fabricated parts. It was found that the CNTs were distributed along the boundaries of the cells of AlSi10Mg. Some of the CNTs reacted to Al4C3 during the SLM process. The combination of CNTs and Al4C3 created a pining effect, while the CNTs still maintained their tubular structure and played a role in loading; this improved the hardness and strength of the matrix material.