The Measurement of Diffusion Coefficients in Solids at Elevated Temperatures: Hydrogen in Steel

AbstractConventional methods for the measurement of diffusion coefficients of species dissolved in solids at elevated temperatures suffer from various difficulties. These include the possibility that adsorption and desorption of species from parts of the apparatus other than the test material contribute to the process. In the present approach a diffusion coefficient is derived from the decrease in both permeability and solubility as a well-defined portion of the test material is removed from the system. In this way the problems described above are essentially eliminated. The method is illustrated by measurements of the diffusion coefficient of hydrogen in rail steel and its general applicability is discussed.