Method of soft metal (Cu) strengthening of Ti3SiC2 was conducted to increase the hardness and improve the wear resistance of Ti3SiC2. Ti3SiC2/Cu composites containing 15 vol.% Cu were fabricated by Spark Plasma Sintering (SPS) in a vacuum. The effect of the sintering temperature on the phase composition, microstructure and mechanical properties of the composites was investigated in detail. The as-synthesized composites were thoroughly characterized by scanning electron micrography (SEM), optical micrography (OM) and X-ray diffractometry (XRD), respectively. The results indicated that the constituent of the Ti3SiC2/Cu composites sintered at different temperatures included Ti3SiC2, Cu3Si and TiC. The formation of Cu3Si and TiC originated from the reaction between Ti3SiC2 and Cu, which was induced by the presence of Cu and the de-intercalation of Si atoms Ti3SiC2. OM analysis showed that with the increase in the sintering temperature, the reaction between Ti3SiC2 and Cu was severe, leading to the Ti3SiC2 getting smaller and smaller. SEM measurements illustrated that the uniformity of the microstructure distribution of the composites was restricted by the agglomeration of Cu, controlling the mechanical behaviors of the composites. At 1000 °C, the distribution of Cu in the composites was relatively even; thus, the composites exhibited the highest density, relatively high hardness and compressive strength. The relationships of the temperature, the current and the axial dimension with the time during the sintering process were further discussed. Additionally, a schematic illustration was proposed to explain the related sintering characteristic of the composites sintered by SPS. The as-synthesized Ti3SiC2/Cu composites were expected to improve the wear resistance of polycrystalline Ti3SiC2.

Ti3SiC2/Cu composites with different Cu content were prepared by spark plasma sintering (SPS) process in vacuum and the effect of Cu content on the microstructure and mechanical property was investigated. The axial displacement, temperature and current of the composites during the sintering process were recorded and discussed. The phase compositions of the original Ti3SiC2 and Cu powder before and after ball-milling, and the as-produced composites were studied by XRD analysis. The surface morphology and fracture surface of the composites were investigated by SEM. The influence of Cu content on the relative density, hardness and compressive strength of the composites was inquired. The results discovered that the phase composition of Ti3SiC2/Cu composites varied with the content of Cu. The phase composition of the Ti3SiC2/5 vol.% Cu composite was composed of Ti3SiC2, Ti5Si3 and Cu3Si, while that of Ti3SiC2/10 vol.% Cu composite and Ti3SiC2/15 vol.% Cu composite contained TiC, besides Ti3SiC2, Ti5Si3 and Cu3Si. Moreover, the relative density of all Ti3SiC2/Cu composites was relatively high (≥93%). With the increase of Cu content, the axial displacement, hardness and compressive strength of the Ti3SiC2/Cu composites increased. Conclusively, the Ti3SiC2/Cu composite with 15 vol.% Cu exhibited better mechanical properties.

The electrochemical corrosion behaviors of Ti 3 SiC 2 /Cu composite and polycrystalline Ti 3 SiC 2 in a 3.5% NaCl medium were investigated by dynamic potential polarization, potentiostat polarization, and electrochemical impedance spectroscopy. The polycrystalline Ti 3 SiC 2 was tested on the identical condition as a control. The characterizations of XRD, X-ray photoelectron spectroscopy, scanning electron microscope, and energy-dispersive spectrometer were used to study the relevant passivation behavior and corrosive mechanism. The self-corrosion current density of Ti 3 SiC 2 /Cu (6.46 × 10 −6 A/cm 2 ) was slightly higher than that of Ti 3 SiC 2 (1.64 × 10 −7 A/cm 2 ). Under open circuit potential, the corrosion resistance of Ti 3 SiC 2 /Cu was better than that of Ti 3 SiC 2 . Ti 3 SiC 2 /Cu exhibited a typical passivation feature with a narrow passivation interval and a breakdown phenomenon. The better corrosion resistance of Ti 3 SiC 2 was due to the more stable Si layer of the former. In comparison, for Ti 3 SiC 2 /Cu composites, Cu reacted with the reactive Si layers in Ti 3 SiC 2 to form Cu-Si compounds and TiC, destroying the weak interaction between Si layers and Ti-C layers. In the other hand, the as-formed Cu-Si compounds and TiC dissolved during the corrosion of Ti 3 SiC 2 /Cu in the 3.5% NaCl medium, causing to the destruction of the passivation film on its surface.