Densification behavior and sintering mechanism of HEA reinforced copper matrix composites Fabricated by spark plasma sintering

Despite growing interest in high-entropy alloy (HEA)-reinforced copper matrix composites, the role of HEA particles in regulating sintering and composite fabrication, as well as the underlying mechanisms, remains insufficiently understood. Herein, the sintering behavior and densification mechanisms of FeNiCrCoCu HEA/Cu composites are systematically investigated by combining molecular dynamics simulations with experimental validation. The composite exhibits a slightly higher sintered density than pure Cu. HEA particles serve as heterogeneous nucleation sites for Cu, promoting nucleation at the HEA/Cu interfaces and subsequent grain growth into the surrounding Cu matrix. As sintering proceeds, Cu grains originating from neighboring HEA particles undergo impingement and competitive growth, thereby regulating grain evolution and resulting in fewer and larger grains, whereas pure Cu exhibits finer grains through homogeneous nucleation. After cooling, the composite exhibits a higher dislocation density, with dislocations bypassing the HEA particles. The heterogeneous deformation behavior is characterized by lower local strain and higher stress within the HEA particles, whereas the Cu matrix accommodates higher local strain. At the atomic scale, the Cu matrix exhibits substantially higher mean square displacement and diffusion coefficients than the HEA phase, while the constituent elements within the HEA exhibit similar migration behavior. In addition, the low interfacial energy and favorable wettability between the two phases, together with interfacial atomic interdiffusion, promote the formation of a well-bonded HEA/Cu interface. This work elucidates the sintering evolution and densification mechanisms of HEA/Cu composites and provides theoretical guidance for their composition design and processing optimization.