Electrochemical corrosion resistance of the amorphous and crystalline Pd-based alloys in simulated seawater

Bulk metallic glasses have been studied and developed as engineering materials due to their outstanding mechanical properties. Corrosion resistance of the bulk metallic glasses is a crucial factor to be considered for their practical applications. In recent years, corrosion properties of a series of amorphous alloys and their crystalline counterparts in corrosive solutions have been reported, but researches on Pd-based alloys are rare. In this paper, the corrosion behaviors of the amorphous and crystalline Pd40.5Ni40.5P19 and Pd77.5Cu6Si16.5 alloys in simulated seawater were investigated. It is found that the surface of both amorphous and crystalline Pd40.5Ni40.5P19 alloys is uniformly corroded without pitting. The corrosion resistance of the crystalline Pd40.5Ni40.5P19 alloy is superior than that of the amorphous Pd40.5Ni40.5P19 alloy due to the inert phosphides and noble palladium phases formed after crystallization. However, different-sized pitting holes are found on the surface of both amorphous and crystalline Pd77.5Cu6Si16.5 alloys, and the amorphous Pd77.5Cu6Si16.5 alloy shows better corrosion resistance than its crystalline counterpart. This phenomenon may be associated with Cu-rich phase on the surface of the crystalline Pd77.5Cu6Si16.5 alloy, which promotes the nucleation of the pitting.