Sintering and deposition of homo- and heteronanoparticles of aluminum and nickel on aluminum (100) substrate

Nanoparticles are very attractive materials owing to their high chemical reactivity compared to conventional micron-sized particles due to their high surface area to volume ratio. In light of this, nanoparticles may provide enhanced energy release rates for explosive and propellant reactions. However, their performance depends strongly on their surface structure. Thereby, nanoparticle coalescence plays an important role as it determines the resultant structure of the active sites where for example catalytic reactions actually take place, i.e. facets, edges, vertices or protrusions. With this in mind, we conduct molecular dynamics simulations to investigate coalescence of two identical nanoparticles of Al and Ni (homo spheres) and two different nanoparticles Al-Ni (hetero spheres) and their deposition on an Al (100) substrate at various temperatures from 200 to 800 K using the embedded atom method. Radial distribution function, x-y plane projection, collapsing and spreading indexes are calculated to characterize the coalescence and surface deposition process. Our simulation results show that the degree of coalescence and deposition are strongly temperature dependent. The deposition rate increases with the temperature while the sintering and deposition of hetero nanoparticles is significant at lower temperatures than melting. This trend is important to develop a lead-free metal composite materials for the electrical interconnect material due to their low processing temperature.