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

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 alpha 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 alpha 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 alpha phases could be bridged by the surrounding matrix oxides during the passivation process, which contributed to decreasing the galvanic corrosion between the alpha phases and the matrix, further improving the corrosion resistance.