In situ synthesis of CNTs in Mg powder at low temperature for fabricating reinforced Mg composites

Carbon nanotube (CNT)/Mg composite powders were synthesized by in situ chemical vapor deposition of acetylene in Co/Mg catalyst powder at 480 °C. The factors influencing the morphology and yield of CNTs, including the compositions of the Co catalyst and the ratio of carbon source to carrier gas, were investigated. For the first time, CNT/Mg composites were fabricated by a powder metallurgy technique using in situ synthesized CNT/Mg powders. The results show that as-obtained CNTs had a mean size of 15 nm and were highly graphitizing and homogeneously dispersed on the Mg powder. Ball milling of CNT/Mg composite powders for short times enabled embedding of CNTs into Mg, resulting in grain refinement. The tensile strength of CNT/Mg composites reached an average of 285 MPa, which is an increase of 45% compared to that of commercial pure Mg.

► Homogeneously dispersed CNTs on Mg powders were synthesized by CVD using a cobalt catalyst.
► Ball milling of CNT/Mg composite powders caused the CNTs to embed into the Mg matrix.
► The hardness of the Mg matrix composites improved by about 25% when the mass fraction of CNTs was 2.4%.
► The tensile strength of the CNT/Mg composites reached a 45% increase over commercial pure Mg.