Effect of material properties on liquid metal embrittlement in the Al–Ga system

There are many examples in which a liquid metal in contact with a polycrystalline solid develops a deep liquid groove at the intersections of the grain boundaries and the solid–liquid interface. In the Al–Ga system, liquid Ga quickly penetrates deep into the solid along grain boundaries resulting in brittle intergranular fracture under even modest stresses, a process known as liquid metal embrittlement. This is a complex phenomenon, involving several different types of simultaneous processes associated with diverse interfacial properties of materials. We have performed molecular dynamics simulations on idealized sets of conditions to emphasize certain effects. We report how Ga propagates into grain boundaries in Al as a function of some important external parameters such as applied stress, temperature, grain boundary type/structure, grain size and liquid properties. Our simulation results are very consistent with both the dislocation-climb model and general trends gleaned from experimental studies in the literature.