Manufacturing of complex-shaped NiCu alloy-diamond composite parts through powder bed fusion (PBF) process

Metal-diamond composites offer outstanding mechanical and thermal properties, but are difficult to fabricate in complex shapes due to the hardness and brittleness of diamond particles. Electron beam powder bed fusion (PBF-EB) enables fabrication of metal-diamond composite parts, but the processing parameters should be carefully controlled to avoid the spattering of diamond and residual porosities. The energy density (E_D) is a common parameter for PBF, but there are still large differences in metallurgical quality of PBF-fabricated samples under the same E_D value. In this work, NiCu-diamond composites were fabricated with same E_D value of 144 J·m⁻¹. A NiCu-diamond composite of high densities (＞97%) and low degrees of spattering of diamond particles was successfully manufactured, when electron beam current is lower than 2.4 mA, and scanning rate is below 1 m·s⁻¹. The transverse rupture strength (TRS) of the diamond composite was as high as 670.2 MPa, and the abrasive ratio was 192.3, both greatly increased in comparison with 556.6 MPa and 179.9, respectively. In order to better understand the relationship between the processing parameters and the printing quality of composite parts, a dynamic parameter, the energy change rate (E_C), as a complementary parameter to the energy density (E_D), was introduced for the first time. It was found that, with the same E_D value, a low E_C value is beneficial for printing the NiCu-diamond composite with high metallurgical quality. The newly proposed E_C parameter also demonstrates similar regularity for optimizing the microstructure and properties of PBF-manufactured various materials (including Ti, Fe and Al alloys). Finally, for the first time, complex-shaped drilling parts were produced by PBF-EB process with the optimized E_C parameter, and showed much better wear resistance compared with that of commercial steel drilling parts. © 2026 Elsevier B.V.