Synthesis of MAX-Phase Ti3SiC2 by Combined Powder Metallurgy Technique

Abstract

The study describes an original approach to the synthesis of composites based on the MAX-phase Ti₃SiC₂ by a combined powder metallurgy technique. The described approach includes a two-stage heat treatment and consolidation of powders by solid-phase vacuum sintering and spark plasma sintering technologies. Powder mixtures 3Ti/1.2Si/2C and Ti/1.2Si/2TiC were considered as feedstocks for the synthesis. The selected mixtures were presintered in a vacuum furnace at a temperature of 1400°C for 1 h. The obtained compacts were milled with the addition of pure silicon powder and spark plasma sintered at a temperature of 1300°C and a pressure of 50 MPa. The silicon overage in each of the sintering steps promoted the phase formation of Ti₃SiC₂. The influence of isothermal holding time at the additional synthesis stage in the range of 5–10 min on phase composition and surface microstructure of the obtained materials was studied. The maximum content of the Ti₃SiC₂ phase, 77.8 vol %, was reached for composites synthesized by the combined sintering of Ti/Si/C and Ti/Si/TiC mixtures at an additional sintering time of 10 and 5 min, respectively. It has been shown that the microstructure of the surfaces of the synthesized composites is represented by elongated grains of the MAX-phase Ti₃SiC₂ with length from 4 to 12 µm, agglomerates of titanium carbide, and precipitations of titanium disilicide.