*2.1. Samples Preparation*

Ti3SiC2/Cu composites were fabricated using powder mixture of Ti3SiC<sup>2</sup> (average particle size: 38 µm, ≥98% purity, 11 technology Co., Ltd., Jilin, China) and Cu (average particle size: 74 µm, ≥99.9% purity, Macklin Biochemical Co., Ltd., Shanghai, China). The content of Cu in Ti3SiC2/Cu composites was 15 vol.%. The mixture with designed composition was first mixed by a ball-milling machine (PMQD2LB, Nanjing Chishun Technology Development Co., Ltd., Nanjing, China) with a rotational speed of 150 rpm and a ratio of ball to powder of 3 for 6 h, then filled into a graphite die (inner diameter: Φ25 mm). Finally, it was sintered by Spark Plasma Sintering (SPS, Model Labox-350, Xinxie, Japan) at different sintering temperatures (950, 1000 and 1050 ◦C, respectively) under a pressure of 35 MPa in vacuum for 20 min and cooled with the furnace. The heating rate was set as follows. From the room temperature to 600 ◦C, the heating rate was 100 ◦C/min. Additionally, from 600 ◦C to the desired sintering temperature, the heating rate was 50 ◦C/min.
