Crystallographic study of liquid-metal-embrittlement crack path

[Display omitted] •The trace analysis was used to investigate the Zn-embrittled grain boundary planes.•Liquid metal penetrates along the grain boundary with high-index planes.•Liquid metal selectively penetrated grain boundary planes of (5 3 1), (5 1 1), & (7 3 3). Compared to other intergranular degradation phenomena, liquid metal embrittlement (LME) is less understood. The main gap in knowledge has been the lack of fundamental information of how grain-boundary characteristics (e.g. grain boundary misorientation angle and grain boundary crystallographic plane) affects LME susceptibility. In this study, the recently developed trace analysis has been applied to the grain boundaries exhibiting LME cracking. Despite the presence of a diverse range of low- and high-index planes in the entire population of the grain boundaries, liquid metal selectively penetrated high-index random grain boundary planes such as (5 3 1), (5 1 1), and (7 3 3).