Effect of particle size on coalescence dynamics and deformation mechanism of the Cu during hot-pressed sintering

Abstract

The existing studies focus on the hot sintering behavior of Cu particles at different temperatures and particle sizes, without considering the effect of pressure on sintering. In addition, the model used in the simulation lacks random distribution, so it is necessary to use a more accurate sintering model. In this work, based on the multi-particle model, the effect of particle size on Cu hot-pressed sintering properties was studied by molecular dynamics method combined with phase-field simulation. The results indicate that the twinning and dislocations formed during the hot-pressed sintering process can enhance the strength and plasticity of Cu. The phase-field results demonstrate the occurrence of particle coalescence during the sintering process, which is in agreement with the molecular dynamics simulation results. During the hot-pressed sintering process, an analysis of the diffusion rate reveals that when the particles are 3–4 nm, the thermal diffusion effect is stronger than pressure. The opposite phenomenon is observed for the particles at 5–8 nm. For particle size is less than 6 nm, grain boundary migration and grain rotation lead to plastic deformation. When the particle size is larger than or equal 6 nm, the plastic deformation is mainly caused by the slip of local and extended dislocations and the deformation twins in the grain.