Microstructural characteristics and mechanical properties of carbon nanotube reinforced AlSi10Mg composites fabricated by selective laser melting

To obtain CNTs/AlSi10Mg alloys with homogeneous microstructure, a new process combines ball milling and selective laser melting (SLM) has been developed. The crystallographic texture, microstructure evolution and mechanical properties of the CNTs/AlSi10Mg alloys produced by SLM at different laser energy densities were investigated. Because of the high temperature and rapid solidification, the special structures of CNTs are destroyed by evaporation and decomposition during the SLM process. Some carbon atoms tend to diffused in the molten pool, which inhabit the grain growth during the SLM process. Under the optimal laser energy density of 131 J/mm3, a fine microstructure with equiaxed crystal was obtained, exhibiting elevated microhardness of 143.7 HV0.1. Compared with that of the unreinforced AlSi10Mg part, the incorporation of CNTs enhanced the Al-based composites strength, but simultaneously deteriorated the ductility of the CNTs/AlSi10Mg parts.