Comparison of carbon-based reinforcement on laser aided additive manufacturing Inconel 625 composites

In this paper, a comparison study of CNTs and graphite addition in laser aided additive manufacturing (LAAM) Inconel 625 composites was proposed. The difference of microstructure and tensile properties between two modified Inconel 625 alloys was investigated. SEM, EDS and micro-Raman identification results showed that the CNTs structure can be found on columnar dendrite boundaries accompanied with precipitated Laves and gamma' phase in LAAM Inconel 625-CNTs composite. Based on tensile test results, 0.25 wt% of CNTs addition in LAAM Inconel 625 can significantly increase strength and ductility by 20% because of grain refinement and grain boundary pinning reinforcement. However, the graphite addition only raises strength but decreases ductility due to carbon content raise.