Thermodynamic parameters for the Ta–Cr–H solid solution from equilibrium (P–C–T) data

•The effect of Cr on the solubility of H in Ta is investigated for the first time.•Hydrogen solubility in Ta decreases with increase in Cr content.•The Heat of reaction for solution of H in Ta–Cr alloys is exothermic in nature.•The relative change in enthalpy for the solution of H in Ta increases with Cr content.

Isothermal pressure–composition–temperature, (P–C–T) equilibrium study for the solubility of hydrogen is investigated over the temperature range of (673 to 873) K to evaluate the relative change in Gibbs energy, enthalpy and entropy for the solution of hydrogen in the Ta–Cr solid solution alloys. The inert gas fusion technique and pressure drop method are used for hydrogen analysis. It is observed that the solubility of hydrogen in tantalum decreases as the Cr content increases. The change in hydrogen solubility in tantalum with increase in Cr content could be explained on the basis of change in strain energy of dissolved hydrogen due to presence of different size interstitial sites around a substituted atom and due to increase in e/a ratio and it may be attributed to repulsive interaction between H and Cr atoms. The exothermic heat of reaction is observed for solution of hydrogen in all the samples.