Understanding the Role of Grain Boundaries in Nanoscale Sintering

Sintering is a processing technique used to consolidate a powder compact and convert it into one with strength and structural integrity. Temperature, pressure, interface structure, and size of initial particles are all factors that contribute to sintering kinetics. Recently, sintering of nanoscale particles has been an area of active research, as it presents many potential advantages, such as lower temperatures, shorter processing times, and the ability to fabricate materials with tailored microstructures, and thus optimal properties. In crystalline materials, when differently oriented particles bond, internal interfaces (i.e., grain boundaries) form. As the particle size is reduced into the nanoscale, the role of grain boundaries (GBs) becomes key due to the increased surface-to-volume ratio and the number of contact points between particles. Herein, atomistic simulations are leveraged to fundamentally understand the role of the grain boundary structure and properties in sintering kinetics. Simulation results reveal a plethora of densification profiles ranging from rapid densification to stagnant behavior depending on the GBs present in the systems. On the whole, our modeling approach provides future avenues to explore the role of interfaces in the sintering behavior of nanoscale powders