Analysis of the partial molar excess entropy of dilute hydrogen in liquid metals and its change at the solid-liquid transition

Abstract

A systematic change in the partial molar enthalpy of mixing (Δh¯Hmix) and partial molar excess entropy (Δs¯Hex) for dilute hydrogen-metal systems at the solid-liquid transition is reported. Expressions for Δh¯Hmix and Δs¯Hex are derived from the Fowler model of hydrogen solubility, and the change in Δs¯Hex at melting is bounded. The theoretical bound is in agreement with measured data. A connection is made between the change in Δs¯Hex and short range order in the metal-hydrogen system.