Gradient structure formation and corrosion behavior of Ti45.5Zr6.5Cu39.9Ni5.1Sn2Si1 amorphous alloy induced by laser surface melting

In the present study, a systematic investigation was conducted to examine the microstructure and corrosion resistance of Ti 45.5 Zr 6.5 Cu 39.9 Ni 5.1 Sn 2 Si 1 alloy with gradient structure induced by laser surface melting treatment. The characterization techniques employed included XRD, SEM, open-circuit potential and polarization curve tests, as well as XPS analysis. The findings revealed the presence of a gradient structure within the alloy, which consisted of an amorphous surface layer, an intermediate amorphous-crystalline composite, and a crystalline titanium alloy substrate. Compared to the crystalline substrate, the fully amorphous structure in the surface layer demonstrated lower passivation current density and higher corrosion and pitting potentials, suggesting superior corrosion resistance. In the transition layer, evidence of galvanic corrosion was observed, with intermetallic compounds of TiCu acting as cathodes against an amorphous matrix anode. The XPS analysis results indicated that surface enrichment of Ti and Zr, coupled with the formation of a dense TiO 2 , Ti 2 O 3 , and ZrO 2 protective film, played a pivotal role in the excellent corrosion resistance of the amorphous layer. However, stress corrosion cracking was observed, which was attributed to residual stresses within the amorphous layer. The findings of this study shed light on the role of laser surface melting in enhancing corrosion resistance of Ti-based amorphous alloys, offering valuable insights for the development of high-performance corrosion-resistant materials and highlighting the necessity of mitigating residual stresses in practical applications.