Effect of Ce on microstructure and corrosion resistance of hot extruded Al-1Mn alloys

The effect of the rare earth element cerium (Ce) on the microstructure and corrosion resistance of hot-extruded Al-1Mn alloys was investigated. The addition of Ce led to a refinement and dispersion of intermetallic particles (IMPs) in the Al-1Mn, forming Ce-containing IMPs (Al20(Mn,Fe)2Ce). These Ce-containing IMPs exhibited a potential difference of approximately 115.5 mV relative to the matrix, which is lower than the 180-190 mV potential difference observed for Ce-free IMPs (Al6(Mn,Fe)). This reduction in potential difference mitigated susceptibility to pitting corrosion. As the Ce content increased, the maximum pitting depth decreased from 145.1 mu m to a minimum of 118.6 mu m at 0.08 wt% Ce, before increasing to 128.5 mu m at 0.12 wt% Ce. Similarly, the corrosion current density during electrochemical testing decreased from 4.2 mu A/cm2 to 1.92 mu A/cm2 and then increased to 6.89 mu A/cm2 with higher Ce content. Furthermore, the corrosion behavior of Al-1Mn alloys with varying Ce contents was analyzed as a function of corrosion time. The results showed that addition of certain amount of alloying element Ce in Al-1Mn alloy can significantly improve its corrosion resistance.