Evaluation of interaction coefficient in Al-Cu-H alloy

The theory for interaction coefficient of alloying additions on hydrogen activity in Al alloys has been generally discussed. In particular, the interaction coefficient of Cu addition on the hydrogen activity for the Al-Cu-H system has been evaluated based on hydrogen solubility values in pure aluminum and in Al-Cu alloy measured at different Cu concentrations by means of Sieverts’ apparatus. The Cu addition was found to reduce the hydrogen solubility, and its effect on hydrogen solubility was evaluated by the interaction coefficient γ H Cu , which is a function of Cu-addition concentration and melt temperature. The evaluated interaction coefficient was converted into an alloy correction factor CF(A) and a temperature correction factor CF(T), which are employed in industrial hydrogen measurement techniques such as TELEGAS and ALSCAN.