Structural and corrosion properties of NiP_x metallic glasses: Insights from EIS and DFT

Despite the increasing interest in metallic glasses for a variety of engineering applications, the structure and corrosion properties still remain unknown. In particular, these properties for Ni-P alloy, a typical metallic glass, are greatly dependent upon the phosphorus content in the alloy. In this report, a relationship between the structural property and the interface corrosion behavior of Ni-P alloys was studied when phosphorus content was intentionally tuned. DFT calculation and EIS measurement were used to determine the electronic structure property and corrosion behavior of Ni-P alloy in acidic Au(III) solution that is applied to the immersion gold process of electroless deposited Ni-P alloys in the manufacture of printed circuit boards. The results indicate that the doped phosphorus atoms are able to bind electrons and change the structure of Ni-P alloy from the metallic to ceramic state, thereby avoiding an overetching in the solution. Theoretical calculation predicts that the anticorrosion ability of Ni-P alloy will be enhanced with phosphorus content. This is in good agreement with experimental data obtained in this work.