Insights into the role of tungsten on corrosion behavior of high-strength Ti alloys

Abstract

High-performance titanium alloys with good corrosion resistance are expected to be applied in marine environments. In this work, we developed a Ti20W alloy using powder metallurgy and hot extrusion, which combined remarkable mechanical properties and good corrosion resistance. The Ti20W alloys exhibited ultrahigh strength (>1400 MPa) and good ductility (>7%), and the specific yield strength was comparable to the common high-strength Ti alloys. The ultrahigh-strength Ti20W alloys had characteristics of the solid solution of W atoms and the precipitation of fine α phases. Compared with Ti6Al4V alloy, the Ti20W alloys showed lower corrosion current density values in 3.5 wt% NaCl solution, which was attributed to the solid solution of W elements and the finer α phases. The W oxides, particularly WO₃, acted as the barrier to effectively block the penetration of Cl⁻ into the inner oxide layer, thereby enhancing the corrosion resistance. The fine α phases could be bridged by the surrounding matrix oxides during the passivation process, which contributed to decreasing the galvanic corrosion between the α phases and the matrix, further improving the corrosion resistance.