Video-investigation of reverse hydride transformations in the Pd–H system

In the present work, peculiarities of β→α hydride transformation in subsurface layers of a β-hydride of palladium in the temperature range 270–100°C were studied. The transformation processes were fixed with video camera in real time and then video movies were analyzed with a Pentium computer. It is shown that a decrease in internal hydrogen phase stresses and hydrogen concentrational ones with increase in temperature strongly influences both morphological peculiarities and the rate of transformation. So, at temperatures of 100–190°C the generation and growth of nuclei can be seen clearly. The features of transformation change with decrease in temperature: at 150°C, nuclei appear one another, the incubation period in subsurface layers consists of 8 s. At 190–170°C, nuclei appear simultaneously without any incubation period. At temperatures of 230–270°C, the transformation proceeds without any relief on the sample surface. The transformation in subsurface layers of a β-PdHx accelerates with temperature increasing from 100°C up to 150°C more than 700 times.