Liquid metal embrittlement mechanism

Liquid metal embrittlement was studied in the following two aspects. First the first principle and Chen-Nanxian three-dimensional lattice reverse meth od were employed to obtain the effective potentials for Al-Ga and Ga-Ga. Th en with the molecular dynamics simulation, the influence of liquid metal ad sorption on dislocation emission was studied. The simulated result shows th at after Ga atoms are adsorbed a the crack plane in Al crystal, the critica l stress intensity factor decreases, which changes from 0.5 MPam(1/2) (with out adsorption) to 0.4 MPam(1/2) (with adsorption). The reason for the redu ction in the critical intensity stress factor is that Ga adsorption reduces the surface energy of the track plane. Moreover, 7075 Al alloy adsorbing l iquid metal (Hg + 3 atm % Ga) was in-situ studied in TEM by using a special constant deflection device. The experimental result showed that liquid met al adsorption could facilitate emission, multiplication and motion of dislo cations. When this process reached a critical condition, the brittle microc rack was initiated and propagated from the crack tip or in a dislocation fr ee zone.