Achieving electrochemical and mechanical stability in a lightweight titanium alloy

Titanium alloys represent a promising material in marine applications, focusing on high-stakes environments where their corrosion resistance and high specific strength offer significant benefits. However, they can still be vulnerable to localized corrosion, such as pitting corrosion and stress corrosion cracking, in the presence of aggressive chlorides. Here we report a lightweight titanium alloy that addresses these issues through conventional casting and thermal-mechanical processing. The alloy can generate a passive film showing distinct but stable electrochemical responses. It is found that the reaction of the passive film can shift from the slow accumulation in the passive region, to the rapid buildup of passive layers in extreme anodic potentials. Consequently, the alloy exhibits a pitting potential above 10 VSCE without being subjected to localized corrosion. Meanwhile, mechanical reliability is also achieved during stress corrosion tests, owing to the fast repair of the passive film that substantially constrains the crack propagation. Such virtual immunity to seawater corrosion qualifies this titanium alloy as a potential candidate for long-term cost savings and sustainability.