First principles screening of B2 stabilizers in CuPd-based hydrogen separation membranes: (1) Substitution for Pd

• Addition of 10 elements lowers the enthalpy of formation noticeably, namely, Mg, Al, Sc, Ti, Y, Hf, Zr, Ga, La, and Zn.
• Compromise between enthalpy and solubility suggests these alloying elements: V, Fe, Cr, Nb, Ta, and Mn.
• Electronegativity correlates qualitatively well with the enthalpy of formation.

We report here a screening study using first-principles method in an attempt to identify ternary elements that can extend the CuPd B2 phase field at reduced Pd contents and thus lower cost. A total of 37 alloying elements are included for unbiased screening. The results show that addition of Mg, Al, Sc, Ti, Y, Hf, Zr, Ga, La, and Zn lowers the enthalpy of formation of the B2 phase noticeably. The atomic size, electronic density of states, charge transfer, and electronegativity are analyzed to interpret the results. Compromise between enthalpy and solubility suggests additional potential alloying elements: V, Fe, Cr, Nb, Ta, and Mn. To assess the effects of alloying on mechanical properties, we calculated the equation of states and elastic constants of 10 example alloys at 6.25 at% solute contents.

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