Effect of rare earth Yb on microstructure and corrosion resistance of ADC12 aluminum alloy

Abstract

Optical microscopy, scanning electron microscopy, energy dispersive spectrometer, and X-ray diffractometer were used to study the effect of rare earth Yb (0, 0.3, 0.6, 0.9, and 1.2 wt%) on microstructure and corrosion resistance of ADC12 aluminum alloy. The results showed the α-Al, eutectic Si and β-Al5FeSi phase in the alloys with addition of rare earth Yb were obviously refined. The Al3Yb intermetallic compound was also observed with 0.9 wt% Yb addition. The immersion and electrochemical test results showed that the corrosion current density (1.27 μA cm−2) of the 0.9 wt% Yb modified alloy was 84.7% lower than that of matrix (8.302 μA cm−2), corresponding weight loss rate of the alloy shows a minimum value for 46 μg cm−2 day−1. Formation of Al3Yb on the cathode Si hindered the growth of the Si phase, which suppressed the corrosion activity of the cathode region and decreased the rate of micro-galvanic corrosion.