Microstructure morphology and concentration modulation of nanocomposite thin-films during simulated physical vapor deposition

Metallic, nanocomposite, thin-films with intertwined morphologies can be synthesized via physical vapor deposition of two immiscible metals. Understanding the phase-ordering kinetics controlling the way the microstructure develops is crucial to obtaining reliable and enhanced functionalities in these nanostructured thin-films. Here, we study the complex relationship between the vapor-deposition conditions and the resulting self-assembled nanoscale morphologies by using phase-field simulations. Our phase-field model accounts for the deposition of the incident vapor phase of a binary alloy onto a substrate, surface interdiffusion, and the subsequent spinodal decomposition in the resulting elastically inhomogeneous thin-film. We systematically investigated the effects of deposition rate, dissimilar bulk and surface kinetics, phase fraction, and dissimilar elastic response on the resulting microstructure. Four distinct classes of achievable self-assembled microstructure morphologies are observed throughout: lateral, vertical, random, and nanoprecipitate concentration modulations. Through our systematic investigation of competing mechanisms, we provide insights on the complex relationships between alloy species and deposition conditions to obtain specific nanostructured morphologies of binary, nanocomposite, thin-films. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.