Elastic fields generated by a semi-spherical hydride particle on a free surface of a metal and their effect on its growth

Structural deformation of metallic uranium surrounding hydride growth sites

“…However, a study reported by Greenbaum et al [31] modelled the elastic fields setup by a semispherical hydride particle growing on a free surface of a metal with cubic symmetry, and concluded that regions of tensile and compressive hydrostatic stress were indeed generated in the surrounding matrix. The work of Greenbaum et al therefore provides a further indication that in the present study internal stresses were generated leading to localised brittle failure of the metal;…”

Preferred hydride growth orientations on oxide-coated gadolinium surfaces

“…A preferred growth of the (1 1 1) h plane of FCC hydrides on the similar structure of the metal atoms -the hexagonal (0 0 .1) m plane of parent HCP metals -have been reported for similar metal-hydride systems (e.g. [5][6][7][8]). Hence, the fact that GdH 2 grows with M-H orientation relationship of (0 0 .1) m ||(1 1 1) h needs no further explanation.…”

“…The development of those GCs also depends on the experimental pressure-temperature conditions and this dependence has been accounted for by a proper kinetic model [2]. It has been proposed [1][2][3] that the transition between the initial hydride spots and the formation of GCs involves the rupture of the oxide layer, thus relieving the stress field exerted on the hydride spot and enabling its further development [5].…”

“…[10]). (iii) Mechanical related effects: The compression of an intact oxidation overlayer on the expanding hydride nuclei (developing beneath that layer), may affect the growth rates of these nuclei [5] and their geometry [11].…”

“…Such orientation relations which usually originate from minimization of misfit strain energies at the interfaces between the original metal and the formed hydride product may be altered by an additional stress field parameter exerted by the oxidation overlayer. The transition between a mechanically stressed process that characterizes the "small family" development, and a "stress-free" process that controls the GCs development [5], may in turn not only affect the growth rates of the two families [5] but may also be manifested in some texture changes displayed by these families.…”