First-principles study of intergranular embrittlement induced by Te in the Ni Σ 5 grain boundary

Tellurium (Te) can lead to stress corrosion cracking in Ni-based Hastelloy N alloy. A first-principles investigation is presented to clarify this mechanism by simulating a Σ 5(0 1 2) symmetrical tilt grain boundary (GB) with the existence of Te. In accordance with previous studies, we confirm preferential substitutional occupation of Te in the GB region. Te tends to form strong bonds with the neighboring Ni atoms. However, Te induces the GB expansion due to the mismatch in atom size, and thus weakens the interfacial Ni-Ni bonds which are essential to the GB cohesion. The effect of the Te concentration in GB is also investigated.