Structure and Properties of Metal Matrix Composites Produced from an 85% Ti + 15% Al Powder Mixture Treated by High-Voltage Electrical Discharge in a Hydrocarbon Liquid

Abstract

Powder composites of the Ti–Al–C system possess high performance characteristics, such as strength and wear resistance, making them suitable for applications in mechanical engineering and the aerospace industry. Physical methods of powder preparation and consolidation, particularly those involving high-voltage electrical discharge and spark plasma sintering, allow the properties of such composites to be improved. This paper examines the influence of high-voltage electrical discharge parameters applied to an 85% Ti + 15% Al powder mixture in a hydrocarbon liquid on the phase composition and mechanical properties of composites produced by spark plasma sintering. High-voltage electrical discharge treatment reduced the average particle size from 20 μm to ~6 μm and simultaneously increased the content of particles smaller than 1 μm to approximately 20%. Furthermore, high-voltage electrical discharge treatment followed by spark plasma sintering enabled the production of composites reinforced with TiC, Ti₂AlC, and Ti₃AlC₂ particles. The metal matrix composites exhibited high mechanical properties: hardness and wear resistance. The highest hardness (HV5 = 4 GPa) among the tested samples was observed in the composites produced from the powder treated at a specific energy input of 10 MJ/kg in ethanol. The absolute wear rate of the composite sample produced from the powder treated in ethanol at 20 MJ/kg was 0.022 g/km, while the relative wear rate was 1.4%/km over a distance of 5 km. For the composite produced from the powder treated in kerosene at 10 MJ/kg, the absolute wear rate was 0.008 g/km and the relative one was 0.68%/km. The samples demonstrated enhanced oxidation resistance, which is attributed to the synthesis of Ti₂AlC and Ti₃AlC₂ MAX phases and titanium carbide within the composite during high-voltage electrical discharge treatment.