New model of phase equilibria in metal - hydrogen systems: Features and software

摘要

A new semi-empirical model of phase equilibria of hydride forming metals and alloys with hydrogen gas (PCT diagrams) has been developed. Within the model, pressure composition isotherms (PCI's) for hydrogen absorption and desorption are presented as pseudo convolutions of one core function, or "ideal" PCI built according to Lacher model, or model of Van der Waals lattice gas, with two modified asymmetric pseudo Voight distribution functions. The median of the absorption distribution is shifted from the one of the desorption distribution towards higher pressures, by the value related to a minimum of a hysteresis free energy (assumed to be constant) and an excessive chemical potential of hydrogen in over-saturated alpha-solid solution.