Thermodynamic model of hydride formation and dissolution in spherical particles
Yuri Mishin, William J. Boettinger
A model of hydride formation and dissolution has been proposed for a single spherical nano-particle and for a colletion of such particles with a given size distribution. The phase transformation strain gives rise to an elastic barrier of the transformation, which scales with the volume of the particle and produces a hysteresis effect known experimentally. The experimentally observed finite slope of the hydrogen pressure versus chemical composition plots (instead of an expected plateau) is explained by the model for both the hydrogenization and dehydrogenization processes. These finite slopes and the amount of pressure hysteresis depend on elastic properties of the hydridge and metal phases, the transformation strain, and on the particle-size distribution in the powder.
hydrogen absorption and desorption, hysteresis, transformation strain, elastic stress