A study on selective laser melting (SLM) of TiC and B4C reinforced IN718 metal matrix composites (MMCs)

Abstract

In this study, TiC and B4C reinforced Inconel 718 (IN718) metal matrix composites (MMCs) have been fabricated using selective laser melting (SLM). The experiments were carried out with varying reinforcement contents (0–30%, in vol%) and laser scanning speeds (500–800 mm/s). A good interfacial bonding between TiC particles and IN718 matrix was observed at all the scanning speeds, whereas B4C/IN718 composites exhibited micro-cracks. Thermal modeling predicted the generation of much higher average von Mises stresses at the interfaces (avg.vmss). The defects in the composites and associated mechanisms were analyzed using a combination of scanning electron microscopy (SEM) and X-ray tomography (XRT). While decrease in the scanning speed decreased the extent of formation of fusion and balling defects, it was found to increase the keyhole porosity. Increasing the scanning speed and TiC content decreased and increased the micro-hardness of the composites, respectively. IN718–30 vol% TiC composite, fabricated using 500 mm/s, was found to exhibit the highest hardness of 619 ± 32.2 HV. The wear resistance first increased as the TiC content was increased to 20 vol%. Further increase in the TiC content to 30 vol% resulted in a decrease in the wear resistance due to higher degree of three-body abrasive wear.