Effect of an Al-TiO2-C-Er2O3 Refining Agent on the Corrosion Resistance of a ZL205 Alloy

In this study, a new type of Al-TiO2-C-Er2O3 refiner was prepared by exothermic dispersion, and the refiner was added to a ZL205 alloy to investigate the effect of the Al-TiO2-C-Er2O3 refiner on the refinement effect and corrosion resistance of the ZL205 alloy. The results reveal that, with the increase in the Er2O3 content, the refining effect is first enhanced and then reduced. The best refining effect of the Al-TiO2-C-Er2O3 refiner was observed by the addition of 6% Er2O3, which refined the grain size of the ZL205 alloy from 147 μm to 103.9 μm, and the grain size was 72% of the ZL205 alloy. The addition of the Al-TiO2-C-Er2O3 refiner led to the improved bias agglomeration of the CuAl2 phase at the grain boundaries in ZL205 and reduced the corrosion sensitivity of the alloy; moreover, the α-Al nucleation temperature of the ZL205 alloy increased, the crystallization interval ΔT of the CuAl2 phase increased from 7.4 °C to 9.3 °C, corresponding to an increase of 1.9 °C, and the self-corrosion current density (icorr) of the ZL205 alloy was reduced from (2.83 × 10−5 A/cm2) to (6.26 × 10−6 A/cm2), a decrease of 77.8%; the polarization resistance (R1 + R2) was 1808.62 Ω·cm2 in comparison with that of the original ZL205 alloy (480.42 Ω·cm2), corresponding to a 276.7% increase.