Role of solute atoms and vacancy in hydrogen embrittlement mechanism of aluminum: A first-principles study

Hydrogen trapping performances of Al with solute atoms X (X = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, or Zn) and X-vacancy defects are investigated using First-principles method. For X-doped Al supercells, most structures show strong alloying ability. Among the solute atoms studied, Cr is the most useful element to trap H due to its lowest H trapping energy. For vacancy@X-doped Al supercells, the strong interactions of X-vacancy are explored. All vacancy@X-doped Al supercells are more favorable to capture H than X-doped Al supercells. In addition, both elastic and chemical interactions should comparably contribute to H-X or H-X-vacancy interactions in Al. Solute atoms and vacancy may regulate electron distribution of Al to enhance the ability of capturing H. Overall, our insights present the quantitative role of solute atoms and vacancy in H trapping for Al, and guide the design of new alloys with high resistance to hydrogen embrittlement.