Thermodynamic Behavior of Dilute Solutions of Hydrogen and Deuterium in Titanium and Zirconium

An investigation has been made of the partial free energy of very dilute solutions of hydrogen and deuterium in the high-temperature, body-centered cubic forms of titanium and zirconium. Anomalous behavior is found which manifests itself as a departure from Sieverts' law. Analysis of the results indicates that there is a strongly marked minimum in the partial enthalpy at hydrogen and deuterium concentrations of about 1 at.% in both metals. This may be associated with a departure from complete randomness in the distribution of interstitial atoms in the solution.