Influence of the milling conditions on the compressive strength of Ti/TiC composite materials sintered at atmospheric pressure

High compressive strength composite materials based on commercially pure titanium were synthesized from Ti Cp grade 2 powders processed by high-energy ball milling using n-hexane as PCA and subsequent sintering in a tubular furnace under argon atmosphere at 1100 °C for 2 h, at atmospheric pressure. The study focused on two main aspects: (i) The effect of speed and milling time on the microstructure and (ii) the relationship between the microstructure and the mechanical resistance of the obtained material. It was found that the presence of TiC was related to the mechanochemical process during milling that occurs under specific conditions of speed and time when enough energy was transferred to the powder coupled with the thermal process at elevated temperature. According to the DSC peaks, the activation energy for the transformations is close to 171 kJ/mol. The microstructure of the sintered samples was characterized by SEM EDS, XRD, and TEM, and the mechanical properties by compression and hardness tests. The high compressive strength of the specimens was attributed to three aspects: (i) the distribution of particles in the sintered samples, (ii) the fine grain size derived from the milling process and (iii) the formation of titanium carbide. A maximum compressive strength of 2.8 GPa makes this material sintered by a simple and low-cost route, very competitive with other advanced Ti composites.