Controlling the corrosion behavior of Ti-Zr alloy by tuning the α/β phase volume fraction and morphology of β phase

Abstract Herein, the influence of relative ratio α and β phases and morphology of β phase on the corrosion behavior of Ti-Zr alloy is systematically studied. The fraction of α and β phases is controlled by carrying out heat treatment at elevated temperatures, followed by water quenching. The electrochemical characterization reveals that the corrosion resistance of Ti47Zr5Al3V (47Zr) alloy in a chloride-containing solution initially decreased with the decrease of α phase fraction, followed by a gradual increase. Moreover, the alloy surface passivation film became rougher with the decrease of α phase content. One should note that the β phase coarsening also decreased the corrosion resistance and increased the surface passivation film roughness of the 47Zr alloy by reducing nucleation sites for the passivation film. In general, the corrosion resistance of two-phase Ti alloy has been significantly affected by the relative content of α/β phases and morphology of β phase, which can be ascribed to the different concentration of nucleation sites for the passivation film and number of galvanic interactions between α and β phases. The detailed X-ray photoelectron spectroscopy (XPS) analysis has been carried out to assess the composition of the passivation film, revealing the presence of TiO2 and ZrO2 as well as a small amount of Al2O3 and V2O5. Despite the fact that the relative fraction of α and β phases and grain size are influenced by the heat treatment, the content of each element in the passivation film remained unchanged. This study provides an insight how the relative phase ratio of α to β and surface morphologies affect Ti corrosion behaviour in the simulated acidic ocean environment.