Effect of Al11Ce3 phase on the mechanical and corrosion properties of Al-Ce-8Mg alloys

The Al-Ce alloys have attracted considerable attention for thermal exchangers and automotive applications owing to their remarkable thermal stability; however, their corrosion behavior remains insufficiently understood. This study aims to investigate the mechanical properties and corrosion behavior of Al-Ce-8Mg alloys with varying Ce contents. The mechanical and corrosion properties of Al-Ce-8Mg alloys with different Ce content were analyzed based on Thermo-Calc calculations, tensile testing, electrochemical impedance spectroscopy and scanning kelvin probe force microscopy. There are three phases in the Al-Ce-8Mg alloys, which are the a-Al(Mg) matrix phase, the primary and the eutectic Al11Ce3 phase. As the Ce content decreases from 9 Wt.% to 5 Wt.%, the hard and brittle primary phase is progressively reduced and eventually eliminated, leading to an improvement in mechanical strength, with an ultimate tensile strength of 251.9 MPa and an elongation of 4.45%. In addition, the overall corrosion resistance of the alloys is improved due to the reduced potential difference between the matrix and the eutectic phase, compared to the difference observed with the primary phase. Although Ce is beneficial for improving the performance of Al alloys at high temperatures, the addition of excessive Ce does not improve the corrosion resistance and mechanical properties of the alloy at room temperature. It is determined that the eutectic Al-Ce phase has superior potential in aerospace and heat-exchanger applications.