Corrosion resistance and passive film stability of laser direct energy deposited TiVZrNbAl lightweight multi-principal element alloy

This work reports the corrosion behaviour of a novel laser direct energy deposited Ti45V30Zr12Nb12Al1 lightweight multi-principal element alloy (MPEA) in a 0.6 M NaCl solution. The MPEA exhibits superior corrosion resistance to typical titanium alloys, including Ti80. Its excellent corrosion resistance is attributed to a passive film with bipolar semiconducting behaviour and an amorphous structure. This unique feature inhibits anion permeation from the electrolyte and cation dissolution from the passive film. Further analyses revealed that Nb alloying effectively reduces the point defect density in the passive film, enhancing its ability to resist attacks by chloride ions.