Study on the compression molding of pure Cu powder particles with a normal distribution of particle size

For the past several years, the behavior of pure Cu powder particles with a normal distribution of sizes during the bidirectional die pressing process has remained a fundamental challenge in the field of powder metallurgy, particularly the interaction between particle size dispersion and stress localization. This study employed a discrete element method–finite element method coupled method to simulate the pressing process of 200 Cu particles with a normal distribution (average diameter: 0.5 mm; standard deviation σ = 0.05, 0.1, and 0.2 mm). The results indicate that, compared to a monodisperse system, increasing the dispersion of particle size (σ = 0.2 mm) can enhance the densification efficiency by 12.3%. This is primarily due to smaller particles filling the interparticle voids during the initial compression. Most importantly, this study identified a unique stress concentration mechanism specific to Cu particle materials: the normal forces between particles are parallel at the interface, leading to local von Mises stress peaks within the particles. This phenomenon does not occur in aluminum or other softer materials. Furthermore, at a compaction pressure of 200 MPa, higher dispersion reduces the pore area by ∼25% and shifts the dominant role in densification from plastic deformation to particle rearrangement. The excellent fit of the Huang Pei Yun and Heckler empirical laws also rigorously validates the model’s effectiveness. These findings address long-standing research gaps and shortcomings in the stress evolution of composite powders and provide an applicable microstructure property framework for the design and production of high density Cu components in aerospace and automotive energy applications.