Experimental study of liquid metal embrittlement for the aluminum 7075–mercury couple

Embrittlement of ductile structural members, whether under the presence of static or cyclic loading, can occur when surrounded by a corrosive environment. Several examples of catastrophic failures due to a form of environmentally assisted cracking (EAC) are available, with the failures of Liberty Ship hulls most commonly referred. Liquid metal embrittlement (LME) is a subset of EAC that results in the embrittlement of structural materials when intimately contacted by specific liquid metals. Several theories exist with the goal of identifying the key microstructural failure mechanism; however, most cannot account for all solid–liquid couples and do not incorporate a form of load dependency. Static and dynamic mechanical testing of notched and cracked specimens, respectively, was implemented to identify the dominant microstructural failure mechanisms and incorporate a load dependency on the life expectation of components. Results reveal crack initiation life behavior that is dependent on the time and load that the structural component remains subjected to LME conditions.

► Liquid metal embrittlement is studied for the Al–Hg couple.
► The influence of stress and stress intensity is observed through experimental mechanics.
► Incubation life data is highly dependent on the oxide layer.
► Microstructural failure mechanism appears to be a combination of two widely known models, the AIDE and DCM models.