Reactions in the Niobium-Hydrogen System

Abstract

Equilibria and elevated‐temperature x‐ray studies show that a solid solution of hydrogen in niobium is produced throughout most of the system. A miscibility gap was found at low temperatures and pressures with a critical point at about 140°C, 0.01 mm of mercury hydrogen pressure, and 0.3 H/Nb. Sorption rates at 300°–550°C were initially linear. At higher temperatures, sorption rates were controlled by diffusion in the metal matrix. Diffusion coefficients at 600°–700°C can be expressed by: