Liquid metal embrittlement of Cu-30%Zn by EGaIn: Microscale fracture toughness by in situ SEM testing

Liquid Metal Embrittlement (LME) of Cu-30 %Zn brass induced by liquid Ga-In eutectic (EGaIn) is investigated through a novel approach that combines in situ scanning electron microscopy (SEM) and micromechanical testing. Unlike macroscopic measurements, at a small scale, the crack initiation process can be sufficiently monitored such that a crack initiation fracture toughness can be derived using Finite Element Modeling (FEM) both at the continuum level or within a Crystal Plasticity framework (CPFEM). Using this new analysis methodology, the measured fracture initiation toughness values, K ½ Jc = 2.00 (FEM) and 2.36 MPa⋅m (CPFEM), are found to be considerably lower than the ones previously measured in the LME literature, thanks to the minimization of plastic zone size effects. These results highlight the critical role of real-time observations in capturing crack nucleation and open a pathway for direct comparison with atomistic fracture models.