Thermal kinetic and mechanical behaviors of pressure-assisted Cu nanoparticles sintering: A molecular dynamics study

Abstract

A molecular dynamics (MD) simulation was performed on the coalescence kinetics and mechanical behavior of the pressure-assisted Cu nanoparticles (NPs) sintering at low temperature. To investigate the effects of sintering pressure and temperature on the coalescence of the nanoparticles, sintering simulations of two halve Cu NPs were conducted at the pressure of 0–300 MPa and the temperature of 300–500 K. A transition of the dominant coalescence kinetics from slight surface diffusion to intensive grain boundary diffusion and dislocation driven plastic flows were found when pressure was applied. Furthermore, atomic trajectories showed the effect of temperature on sintering was strongly dependent on the microstructures of Cu NPs. The atomic diffusion around defects can be significantly promoted by the elevated temperature. Additionally, based on the sintered structures, uniaxial tension simulation was implemented with a constant strain rate. Stress–strain curves and evolution of dislocation activities were derived. Improved mechanical behaviors, including larger elastic modulus and larger tensile strength, were obtained in the structure sintered under higher pressure and temperature. Among this study, sintering temperature and pressure consistently exhibited the same relative impact on affecting both coalescence and the mechanical properties of the sintered structure.