|About this Abstract
|2022 TMS Annual Meeting & Exhibition
|Seeing is Believing -- Understanding Environmental Degradation and Mechanical Response Using Advanced Characterization Techniques: An SMD Symposium in Honor of Ian M. Robertson
|The Central Role of the Chemical Potential of Hydrogen Regarding Hydrogen Ingress, Trapping, Defect Generation and Fracture
|On-Site Speaker (Planned)
Corrosion reactions determine the maximum chemical potential of hydrogen. Examples for iron, nickel and aluminum are presented. The self-diffusion coefficient of hydrogen in the metal is determined by the product of the H-diffusion in the perfect lattice times the fraction of hydrogen being diffusible. In this context, the quantities diffusible hydrogen, lattice hydrogen, thermodynamic activity of hydrogen and chemical potential of hydrogen are interchangeable in a general way. New discontinuities (fracture surfaces, voids, dislocations) are generated during hydrogen embritllement. The production rate of these discontinuities depends on the chemical potential of hydrogen within the defactant concept or the generalized Gibbs adsorption isotherm. Thus, the chemical potential of hydrogen determines both the amount of trapping and the defect generation rate. For a crack the chemical potential affects its velocity independent of the accompanying concentration enhancement in front of the crack tip or the H-coverage on the freshly generated crack surface.
|Environmental Effects, Modeling and Simulation, Other