The nucleation and growth of H blisters in dislocation loops in W{110}

• The vacancy-type dislocation loops are energetically preferred to be present on W{110} planes.
• The nucleation and growth of H blisters on dislocation loops in W{110} planes are thoroughly addressed.
• H2 molecules are observed in the H blisters, and the corresponding physical insight is revealed.

We propose a mechanism for nucleation and growth of H blisters in vacancy-type dislocation loops (DLs) in tungsten (W), based on the first principles calculations. We find that vacancy-type DLs are energetically preferred to form on {110} planes. The H atoms nearby are readily to migrate to and accumulate in the DLs with energy cost less than 0.24 eV. With the increasing number of the trapped H atoms, the DL expands rapidly, consequently, the nucleation and growth of H blisters is completed in the DL gradually. In addition, H2 molecules are observed in the H blisters when the H areal density in DL reaches to be of 6.3 × 1015 atoms/cm2 (the number of H atoms per the cross-sectional area of the DL). Our proposed formation mechanism for H blisters in W material may also be applicable to other metals and metal alloys.