Laser Deposited In-Situ TiC Reinforced Nickel Matrix Composites: Microstructure and Tribological Properties

A new class of Ni-Ti-C based metal matrix composites has been developed using the laser engineered net shaping (LENS) process. These composites consist of an in situ formed and homogeneously distributed titanium carbide (TiC) phase reinforcing the nickel matrix. Additionally, by tailoring the Ti/C ratio in these composites, an additional graphitic phase can also be engineered into the microstructure. The microstructure of these composites has been characterized in detail in three dimensions, via serial-sectioning in a dual-beam focused ion beam instrument followed by appropriate 3D reconstructions, to determine the true morphology and spatial distribution of the TiC and graphite phases as well as the phase evolution sequence. These three-phase Ni-TiC-C composites exhibit excellent tribological properties, in terms of extremely low coefficient of friction while maintaining a relatively high hardness, and these will be discussed in the presentation.