Effect of Widmanstatten Structure on Protection Potential of Ti-6Al-2Sn-4Zr-2Mo (0.1Si) Alloy in 1 M NaBr Solution

Three different microstructures, Widmanstatten structure, acicular martensite, and α-plates, have been produced through suitable heat treatments for alloy Ti-6Al-2Sn-4Zr-2Mo (0.1Si). The influence of these microstructures on pitting corrosion in 1 M NaBr solution has been studied using polarization technique. It is found that the parameters, pitting potential (E_pit) and protection potential (E_pp), are significantly influenced by the heat treatment conditions. E_pit increases in the order α-plate < Widmanstatten structure < acicular martensite, while in the case of E_pp, the value increases in the order Widmanstatten structure < α-plates < acicular martensite. The poor E_pp value in the case of Widmanstatten structure is attributed to the inherent variations in Mo and Al content between the plates accompanied by the formation of this phase.