*Article* **Microstructure and Mechanical Properties of Composites Obtained by Spark Plasma Sintering of Ti3SiC2-15 vol.%Cu Mixtures**

**Rui Zhang 1,2,3,\*, Biao Chen <sup>4</sup> , Fuyan Liu 5,\* , Miao Sun <sup>1</sup> , Huiming Zhang <sup>1</sup> and Chenlong Wu <sup>4</sup>**


**Abstract:** Method of soft metal (Cu) strengthening of Ti3SiC<sup>2</sup> was conducted to increase the hardness and improve the wear resistance of Ti3SiC<sup>2</sup> . 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 Ti3SiC<sup>2</sup> , Cu3Si and TiC. The formation of Cu3Si and TiC originated from the reaction between Ti3SiC<sup>2</sup> and Cu, which was induced by the presence of Cu and the de-intercalation of Si atoms Ti3SiC<sup>2</sup> . OM analysis showed that with the increase in the sintering temperature, the reaction between Ti3SiC<sup>2</sup> and Cu was severe, leading to the Ti3SiC<sup>2</sup> 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 Ti3SiC<sup>2</sup> .

**Keywords:** MAX phase; SPS; Ti3SiC2/Cu composites; sintering characteristic
