Liquid metal embrittlement (LME) refers to the reduction in ductility and toughness of a solid metal when in contact with some liquid metals. This kind of material property degeneration poses a serious challenge for several industrial sectors, including the automotive industry, in which the embrittlement of advanced high-strength steels by their liquified Zn coating layer during welding is of major concern.This makes Fe in contact with liquid Zn a highly relevant example of an LME-susceptible metal couple and the focus of the present study.

To aid the elucidation of the atomic-scale origins of LME in this regard, we establish an atomistic simulation framework, which offers sufficient versatility and computational efficiency for the assessment of general grain and phase boundaries. This framework takes the form of a K-controlled molecular dynamics (K-test) setup for interfacial cracks. The simulation domain is confined to the area of interest regarding LME, i.e. the near-crack tip region, and can be constructed in accordance with the theory of anisotropic linear elastic fracture mechanics. The employment of the Stroh formalism allows accounting for cracks along the boundaries of arbitrarily oriented dissimilar anisotropic materials and the simulation of mode I, II, III and mixed-mode loading cases.

The established simulation setup is benchmarked against existing K-test studies of cracks in homogeneous materials and along symmetric tilt GBs. Next, the full capability of our approach is demonstrated by the example of high-misorientation angle random and arbitrarily oriented GBs. The obtained results are confronted with analytical theories to assess their validity. General aspects of the implementation are clarified, like the construction of the simulation domain and the influence of lattice trapping effects. Finally, the employment of the established general K-test framework is discussed in the context of LME.