Direct metal laser sintering synthesis of carbon nanotube reinforced Ti matrix composites: Densification, distribution characteristics and properties

摘要

Carbon nanotubes (CNTs) reinforced Ti matrix composites with tailored microstructures and properties were fabricated by direct metal laser sintering (DMLS). A relationship of processing conditions, distribution characteristics of CNTs, and properties was established. The appearance of balling phenomenon and micropores at relatively low laser energy input reduced the densification level of DMLS CNTs/Ti composites. As a η of 700 J/m was properly settled, the composite part with a near-full 96.8% density was obtained. On increasing the laser energy input, the distribution states of CNTs in Ti matrix changed markedly from agglomeration to homodisperse. The optimally prepared fully dense CNTs/Ti composite with uniform distribution of CNTs had significantly enhanced H_d of 9.4 GPa and E_r of 328 GPa, which showed respectively ～2.5- and ～3.4-fold increase upon that of unreinforced Ti, and resultant a relatively low friction coefficient of 0.23 and reduced wear rate of 3.8 × 10~(-5) mm~3/(N m).