The Role of Confinement on Stress-Driven Grain Boundary Motion in Nanocrystalline Aluminum Thin Films

3D molecular dynamics simulations are performed to investigate the role of microstructural confinement on room temperature stress-driven grain boundary (GB) motion for a general population of GBs in nanocrystalline Al thin films. Detailed analysis and comparison with experimental results reveal how coupled GB migration and GB sliding are manifested in realistic nanoscale networks of GBs. The proximity of free surfaces to GBs plays a significant role in their mobility and results in unique surface topography evolution. We highlight the effects of microstructural features, such as triple junctions, as constraints to otherwise uninhibited GB motion. We also study the pinning effects of impurities segregated to GBs that hinder their motion. Finally, the implications of GB motion as a deformation mechanism governing the mechanical behavior of nanocrystalline materials are discussed. Disciplines Materials Science and Engineering Comments Gianola, D. S., Farkas, D., Gamarra, M., & He, M. (2012). The role of confinement on stress-driven grain boundary motion in nanocrystalline aluminum thin films. Journal of Applied Physics, 112(12), 124313. doi: 10.1063/1.4770357 Copyright 2012 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This journal article is available at ScholarlyCommons: http://repository.upenn.edu/mse_papers/223 The role of confinement on stress-driven grain boundary motion in nanocrystalline aluminum thin films Daniel S. Gianola, Diana Farkas, Martin Gamarra, and Mo-rigen He Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061, USA (Received 23 September 2012; accepted 19 November 2012; published online 21 December 2012) 3D molecular dynamics simulations are performed to investigate the role of microstructural confinement on room temperature stress-driven grain boundary (GB) motion for a general population of GBs in nanocrystalline Al thin films. Detailed analysis and comparison with experimental results reveal how coupled GB migration and GB sliding are manifested in realistic nanoscale networks of GBs. The proximity of free surfaces to GBs plays a significant role in their mobility and results in unique surface topography evolution. We highlight the effects of microstructural features, such as triple junctions, as constraints to otherwise uninhibited GB motion. We also study the pinning effects of impurities segregated to GBs that hinder their motion. Finally, the implications of GB motion as a deformation mechanism governing the mechanical behavior of nanocrystalline materials are discussed. VC 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4770357]