High temperature interfacial dynamics in Nickel coated Aluminum nanoparticles

Abstract

Molecular dynamics simulations are used to investigate the thermal stability of Al-Ni core–shell nanoparticles (NP) with different core sizes and shell thicknesses. Our study reveals that a distinct two-stage melting occurs during the continuous heating of bimetallic NPs. Unlike previous studies for single NP, where melting start from the outer surface and gradually encompass the core of the material, our result clearly indicates the interface dominated melting phenomena. It is evidenced in our analysis through microstructure, coordination number, and Lindemann index, that this interface dominated phenomena does not alter with decreased shell thickness. We estimate that the interfacial misfit, and bond energy orders (Ni-Al, Al-Al, and Al-Al) are the sources of such premelting phenomena to be nucleated at the interface. This study provides a fundamental perspective on the melting behavior of bimetallic nanoparticles and can be extended towards multimetallic NPs at the atomic level.