• The influence of trace Y and Hf on the corrosion properties and passivation of the Al 1.5 TiVNb LHEA was investigated using a series of techniques, including various electrochemical testing, Mott-Schottky analysis, and XPS. • The incorporation of trace Y and Hf notably enhanced the pitting potential and expanded the passive window, resulting in superior corrosion resistance. XPS results indicated a 50% higher TiO 2 content in the passive film of the Y/Hf doped Al 1.5 TiVNb LHEA. • The addition of Y and Hf increased point defect density, which was proposed to promote local reactions and facilitate the passivation and repassivation processes. This finding offers a valuable pathway for designing corrosion-resistant alloys. In this study, corrosion-resistant Al 1.5 TiVNb lightweight high entropy alloys (LHEAs) with and without Y, Hf were prepared via arc melting. Microstructure of the alloys was characterized using a scanning electron microscope (SEM) and transmission electron microscope (TEM). The influences of trace Y and Hf on corrosion properties and passivation of Al 1.5 TiVNb LHEA in 0.6 mol/L NaCl electrolyte were thoroughly investigated using a series of techniques, including various electrochemical testing, Mott-Schottky analysis, and X-ray photoelectron spectroscopy (XPS). Incorporating trace Y and Hf enhanced pitting potential and passive window of LHEA, concurrently decreasing corrosion current density and improving alloy’s corrosion resistance. This was due to a 50% higher TiO 2 content in the passive film of Y/Hf-doped Al 1.5 TiVNb LHEA than that of Y/Hf-free counterpart. This was resulted from the higher density of point defects (based on M-S analysis) after adding Y and Hf, which enhanced local reactions and facilitated the passivation and repassivation of the alloy.
Shi et al. (Sun,) studied this question.