*Article* **Fabrication of Titanium and Copper-Coated Diamond/Copper Composites via Selective Laser Melting**

**Lu Zhang <sup>1</sup> , Yan Li 1,2 , Simeng Li <sup>1</sup> , Ping Gong <sup>1</sup> , Qiaoyu Chen <sup>1</sup> , Haoze Geng <sup>1</sup> , Minxi Sun <sup>1</sup> , Qinglei Sun 1,\* and Liang Hao 1,2,\***


**Abstract:** The poor wettability and weak interfacial bonding of diamond/copper composites are due to the incompatibility between diamond and copper which are inorganic nonmetallic and metallic material, respectively, which limit their further application in next-generation heat management materials. Coating copper and titanium on the diamond particle surface could effectively modify and improve the wettability of the diamond/copper interface via electroless plating and evaporation methods, respectively. Here, these dense and complex composites were successfully three-dimensionally printed via selective laser melting. A high thermal conductivity (TC, 336 W/mK) was produced by 3D printing 1 vol.% copper-coated diamond/copper mixed powders at an energy density of 300 J/mm<sup>3</sup> (laser power = 180 W and scanning rate = 200 mm/s). 1 and 3 vol.% copper-coated diamond/copper composites had lower coefficients of thermal expansions and higher TCs. They also had stronger bending strengths than the corresponding titanium-coated diamond/copper composites. The interface between copper matrix and diamond reinforcement was well bonded, and there was no cracking in the 1 vol.% copper-coated diamond/copper composite sample. The optimization of the printing parameters and strategy herein is beneficial to develop new approaches for the further construction of a wider range of micro-sized diamond particles reinforced metal matrix composites.

**Keywords:** selective laser melting; thermal management materials; titanium-coated diamond/copper composites; copper-coated diamond/copper composites
