Molecular dynamics on the sintering mechanism and mechanical feature of the silver nanoparticles at different temperatures

In the current study, molecular dynamics analysis to the melting and sintering process of silver nanoparticles (AgNPs) with different sizes is performed. The evolution of dihedral angle, neck width, Radial Distribution Function, and Mean Square Displacement during sintering have been investigated. It is noted that larger particles have higher neck growth, and smaller particles show faster sintering neck growth rate. The necking growth of AgNPs is caused by surface and volume diffusion. When the surface diffusion dominates at the early sintering stage, the neck growth rate is slowly accompanied by changing of the crystal structure. The neck width and dihedral angle change obviously with the volume diffusion. In addition, the evolution of various types of dislocations during sintering has been explored by the common neighborhood analysis. It has been found that the Hirth dislocations being developed at the sintering temperature ranges of 440–685 K, the non-slide Hirth dislocations improve the ability of the nano-silver structure to resist deformation and have better mechanical properties. It explains why the sintering temperature of AgNPs is usually set at 473–573 K from a microscopic perspective. The development of non-slip dislocations in this temperature range improves the mechanical strength of sintered AgNPs. The variations of tensile strength with different neck width and temperatures during the sintering process have been investigated. The relationship between elastoplastic deformation and dislocation evolution is obtained from the atomic level. It is recognized that the tensile strength of AgNPs is directly proportional to the neck width. On the other hand, due to the Hirth dislocation effect, the AgNps with smaller particle sizes show stronger susceptibility to ductile fracture.