Effect of TiC and TiB2 Reinforcement Phase Addition on Mechanical and Tribological Properties of NiAl-TiC-TiB2 Composite Produced Through Combustion Synthesis Process

Abstract

Abstract Introduction: In this research, NiAl-TiC-TiB2 composites with different contents of TiC-TiB2 were produced via the self-propagating high-temperature synthesis (SHS) process using the exothermic reactions in compressed mixtures of Ni, Al, Ti, and B4C. Methods: The synthesis of composites was performed using induction assisted heating, and the formation of phases and the morphology of reinforcing particles were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques, respectively. Findings: Results indicate that the TiC-TiB2 ceramic phases were successfully synthesized and dispersed throughout a NiAl matrix. By increasing the TiC-TiB2 content, the porosity in the structure gets a rising trend due to the enhancement of reaction kinetics and intensity of the reaction, and reaches from 24 Vol.% in the sample without reinforcement phases to 39% in the sample with 15% of ceramic reinforcements. Evaluation of mechanical and tribological properties of the fabricated ceramic samples shows that - although the addition of TiC-TiB2 increases the volume fraction of voids which cause destructive effects - a desirable distribution of ceramic particles within the NiAl matrix leads to improved properties for the composite. The distribution of TiC-TiB2 particles throughout the matrix results in a remarkable decrease in sample weight loss in the pin-on-disk wear test. Also, the microhardness mean values increase from 497 HV for the unreinforced NiAl sample to values up to 1015 HV for the composite sample containing 15% of reinforcing particles.

Keywords

• combustion synthesis
• intermetallic-matrix composites
• self-propagating high-temperature synthesis
• tribological behavior