Structure and Deformation Behavior of Ti-SiC Composites Made by Mechanical Alloying and Spark Plasma Sintering

Combining high energy ball milling and spark plasma sintering is one of the most promising technologies in materials science. The mechanical alloying process enables the production of nanostructured composite powders that can be successfully spark plasma sintered in a very short time, while preserving the nanostructure and enhancing the mechanical properties of the composite. Composites with MAX phases are among the most promising materials. In this study, Ti/SiC composite powder was produced by high energy ball milling and then consolidated by spark plasma sintering. During both processes, Ti₃SiC₂, TiC and Ti₅Si₃ phases were formed. Scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction study showed that the phase composition of the spark plasma sintered composites consists mainly of Ti₃SiC₂ and a mixture of TiC and Ti₅Si₃ phases which have a different indentation size effect. The influence of the sintering temperature on the Ti-SiC composite structure and properties is defined. The effect of the Ti₃SiC₂ MAX phase grain growth was found at a sintering temperature of 1400-1450 °C. The indentation size effect at the nanoscale for Ti₃SiC₂, TiC+Ti₅Si₃ and SiC-Ti phases is analyzed on the basis of the strain gradient plasticity theory and the equation constants were defined.