title: Growth Twinning and Generation of High-Frequency Surface Nanostructures in Ultrafast Laser-Induced Transient Melting and Resolidification.
abstract: The structural changes generated in surface regions of single crystal Ni targets by femtosecond laser irradiation are investigated experimentally and computationally for laser fluences that, in the multipulse irradiation regime, produce sub-100 nm high spatial frequency surface structures. Detailed experimental characterization of the irradiated targets combining electron back scattered diffraction analysis with high-resolution transmission electron microscopy reveals the presence of multiple nanoscale twinned domains in the irradiated surface regions of single crystal targets with (111) surface orientation. Atomistic- and continuum-level simulations performed for experimental irradiation conditions reproduce the generation of twinned domains and establish the conditions leading to the formation of growth twin boundaries in the course of the fast transient melting and epitaxial regrowth of the surface regions of the irradiated targets. The observation of growth twins in the irradiated Ni(111) targets provides strong evidence of the role of surface melting and resolidification in the formation of high spatial frequency surface structures. This also suggests that the formation of twinned domains can be used as a sensitive measure of the levels of liquid undercooling achieved in short pulse laser processing of metals.
authors.affiliation: Univ Lyon, UJM-Saint-Etienne, CNRS, IOGS, Laboratoire Hubert Curien UMR5516, F-42023 St-Etienne, France.
authors.forename: Xxx
authors.initials: X
authors.lastname: Sedao
authors.affiliation: Department of Materials Science and Engineering, University of Virginia , 395 McCormik Road, Charlottesville, Virginia 22904-4745, United States.
authors.forename: Maxim V
authors.initials: MV
authors.lastname: Shugaev
authors.affiliation: Department of Materials Science and Engineering, University of Virginia , 395 McCormik Road, Charlottesville, Virginia 22904-4745, United States.
authors.forename: Chengping
authors.initials: C
authors.lastname: Wu
authors.affiliation: Univ Lyon, INSA Lyon, CNRS, MATEIS, UMR 5510, F-69621 Villeurbanne, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Douillard
authors.affiliation: Univ Lyon, INSA Lyon, CNRS, MATEIS, UMR 5510, F-69621 Villeurbanne, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Esnouf
authors.affiliation: Ecole Nationale Supérieure des Mines de Saint-Etienne, Laboratoire Georges Friedel, CNRS, UMR5307, 42023 St-Etienne, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Maurice
authors.affiliation: Univ Lyon, UJM-Saint-Etienne, CNRS, IOGS, Laboratoire Hubert Curien UMR5516, F-42023 St-Etienne, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Reynaud
authors.affiliation: Univ Lyon, UJM-Saint-Etienne, CNRS, IOGS, Laboratoire Hubert Curien UMR5516, F-42023 St-Etienne, France.
authors.forename: Florent
authors.initials: F
authors.lastname: Pigeon
authors.affiliation: Univ Lyon, UJM-Saint-Etienne, CNRS, IOGS, Laboratoire Hubert Curien UMR5516, F-42023 St-Etienne, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Garrelie
authors.affiliation: Department of Materials Science and Engineering, University of Virginia , 395 McCormik Road, Charlottesville, Virginia 22904-4745, United States.
authors.forename: Leonid V
authors.initials: LV
authors.lastname: Zhigilei
authors.affiliation: Univ Lyon, UJM-Saint-Etienne, CNRS, IOGS, Laboratoire Hubert Curien UMR5516, F-42023 St-Etienne, France.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Colombier
keywords: growth twin; high-frequency surface nanostructures; laser-induced lattice defects; laser-induced periodic surface structures; transient melting and resolidification; ultrafast laser