Microstructure, mechanical properties and strengthening mechanisms of in-situ prepared (Ti5Si3 + TiC0.67)/TC4 composites

Hybrid (Ti5Si3 + TiCx) (x = 0.67) particles reinforced TC4 matrix composites were in-situ prepared by hot-press sintering, basing on the reactions between Ti3SiC2 and Ti. To research the effects of Ti3SiC2 content on the microstructures and mechanical properties, 1–10 wt% Ti3SiC2 were selected. When Ti3SiC2 content was less than 5 wt%, Si element dissolved in the matrix, and TiCx distributed in the matrix homogeneously. While the content exceeded 5 wt%, Si was precipitating as Ti5Si3 attaching to TiCx particles, which resulted in the aggregations of reinforcements. The micro-hardness of matrix was improved with the solid solubility of Si increasing in matrix, and the compressive strength was improved with Ti3SiC2 content increasing. The hardness was mainly affected by solid solution strengthening. The compressive strength was affected by the solid solution strengthening, fine-grain strengthening and the improvement effect of reinforcements. It was determined that solid solution strengthening played the major role by theoretical calculation.