Role of process control agent in the production of Al2O3-reinforced titanium matrix composites

Abstract

Metal Matrix Composites (MMCs) have recently been preferred over traditional materials in many engineering applications. Titanium matrix composites (TMCs) are used in the automotive, aerospace and defence industries thanks to their exceptional strength, high fatigue strength, good corrosion resistance and high elastic modulus. Some of the most used reinforcement materials for TMCs are SiC, Zr2O3, Al2O3, graphene, carbon nanotube (CNT) and TiC. In this study, TMCs reinforced Al2O3 were produced via conventional powder metallurgy (PM) and ultrasonic-assisted mixing. An Al2O3 in varying amounts (5 and 10 wt%) was incorporated into the TMCs via mechanical alloying (MA) for 5 h in a high-energy ball mill and using different process control agents (PCA, Stearic acid (SA), Polyvinyl Alcohol (PVA), Ethanol). The mechanically alloyed (MA'ed) powders were compacted by a hydraulic press under uniaxial pressure of 450 MPa and sintered at 1200 °C for 2 h in an argon atmosphere. The microstructural, mechanical and tribological properties of Ti-xAl2O3 powders and bulk samples were investigated. The highest hardness and the lowest specific wear rate were found in specimens reinforced with 5 wt% Al2O3, using ethanol as PCA, and produced by ultrasonic-assisted mixing, but the same specimen had the lowest compressive strength.