title: Chemomechanical Origin of Hydrogen Trapping at Grain Boundaries in fcc Metals.
abstract: Hydrogen embrittlement of metals is widely observed, but its atomistic origins remain little understood and much debated. Combining a unique identification of interstitial sites through polyhedral tessellation and first-principles calculations, we study hydrogen adsorption at grain boundaries in a variety of face-centered cubic metals of Ni, Cu, γ-Fe, and Pd. We discover the chemomechanical origin of the variation of adsorption energetics for interstitial hydrogen at grain boundaries. A general chemomechanical formula is established to provide accurate assessments of hydrogen trapping and segregation energetics at grain boundaries, and it also offers direct explanations for certain experimental observations. The present study deepens our mechanistic understanding of the role of grain boundaries in hydrogen embrittlement and points to a viable path towards predictive microstructure engineering against hydrogen embrittlement in structural metals.
authors.affiliation: Department of Mining and Materials Engineering, McGill University, Montréal, Québec H3A 0C5, Canada.
authors.forename: Xiao
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Department of Mining and Materials Engineering, McGill University, Montréal, Québec H3A 0C5, Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Marchand
authors.affiliation: Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: McDowell
authors.affiliation: Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
authors.forename: Ting
authors.initials: T
authors.lastname: Zhu
authors.affiliation: Department of Mining and Materials Engineering, McGill University, Montréal, Québec H3A 0C5, Canada.
authors.forename: Jun
authors.initials: J
authors.lastname: Song