Properties of hydride-forming metals and of multilayer hydrogen permeation barriers

Abstract

Interference microscopy and scanning electron microscopy have been used to measure mechanical effects of tritium decay and 3He accumulation in thin film tritides of Sc, Ti, Y, Ho, and Er, all of which exhibit thickness increase of 2–4% y −1, followed by the development of bubbles and craters and the occurrence of significant mechanical film failure. Scandium and erbium deuterotritide films have been subjected to 20 keV N 2 + ion bombardment in an ion microprobe mass analyzer to produce sputter ion species characteristic not only of the original film (e.g., M +, MO +, MD +, MT +) but also of compounds formed during the sputtering operation (e.g., ScN +). Hydrogen isotope permeation has been measured for the homogeneous metals Cu, Ceramvar and Mo, for a Ceramvar-copper-Ceramvar laminate, and for tin-coated Rodar. Measured permeation rates through the laminate are significantly less than those predicted from the permeabilities of its individual constituents. Permeation rates of deuterium through Mo exhibit a somewhat lower activation energy than has been reported in the literature.