Publication details

Authors: Lu, Y. Y.; Kotoka, R.; Ligda, J. P.; Yarmolenko, S. N.; Schuster, B. E.; Wei, Q. 
Title: Morphological and mechanical stability of HCP-based multilayer nanofilms at elevated temperatures 
Type: Journal Article 
Publisher: Surface and Coatings Technology 
Year: 2015 
Volume: 275 
Start Page: 142 
End Page: 147 
DOI: 10.1016/j.surfcoat.2015.05.027 
Abstract: The thermal stability of Mg/Ti multilayer nanofilms was investigated by examining their microstructure and nanoindentation hardness after annealing at various temperatures and time periods. The multilayers with individual layer thickness h >= 5 nm exhibit excellent capability of maintaining the lamellar microstructure and high strength up to 200 degrees C for annealing time up to 2.0 h. The annealed muldlayer films with h = 2.5 nm are still highly textured but characterized with discontinuous layer interfaces, in which the transition of atomic arrangement from hexagonal close-packed (HCP) to body-centered cubic (BCC) structure was observed at columnar boundaries. The degradation of uniform lamellar microstructure is related to the decrease of hardness with annealing temperature at this size scale. A diffusion based instability mechanism was proposed for this typical HCP-based nanoscale multilayer system. (C) 2015 Elsevier B.V. All rights reserved. 
Keywords: metallic multilayer, thermal stability, microstructure, nanoindentation hardness, scale-dependent deformation, plate-like structures, thermal-stability, shape instabilities, magnetic-properties, co/cu multilayers, phase-transition, columnar growth, thin-films, microstructure