Laser rapid forming processing of TiC reinforced nickel-based superalloy composites: Influence of additive TiC particle content

Abstract

The present investigation concerned the fabrication of TiC (2.5 and 5 wt. %) reinforced nickel-based superalloy (NBS) composites by laser rapid forming (LRF) with a high power diode laser. Furthermore, the evaluation of microstructures and the wear resistance of the laser manufacturing specimens were researched. There were four different species of microstructures in LRF-processed pure NBS parts and 2.5% TiC/NBS composites, including cellular grains, columnar grains, crosslike grains, and columnar dendrites. However, only cellular grains could be observed in the 5% TiC/NBS composite parts. Moreover, when micro-TiC particles were added as reinforcements, relatively coarsening microstructures were obtained by the LRF processing compared with the unreinforced NBS parts. Generally, the LRF-processed 5% TiC/NBS composites showed the best efficiency in improving the tribological property compared with the pure NBS and 2.5% TiC/NBS composite parts. It indicated that the dominant wear mechanism was adhesive wear when unreinforced NBS sliding against GCr15 counterpart ball, while 2.5% TiC/NBS composite underwent adhesive wear and abrasive wear simultaneously. However, the predominant wear mechanism of 5% TiC/NBS composite changed into abrasive wear. The energy dispersive x-ray spectroscopy analyses could be the evidence that oxidative wear also occurred between the sliding pair of TiC/NBS composites and GCr15 during the dry sliding wear test.