Corrosion behavior of Al-Al₃Ni and Al-Al₂Cu functionally graded materials fabricated by a centrifugal method

Intermetallic compounds, such as Al₃Ni and Al₂Cu, are effective for enhancing the mechanical properties of an alloy. Al-Al ₃Ni and Al-Al₂Cu functionally graded materials (FGMs) might be attractive materials for advanced materials. Al-Al₃Ni and Al-Al₂Cu FGMs were fabricated by a centrifugal method; the centrifugal method is an extremely effective method for fabricating FGMs. Al-Al₃Ni and Al-Al₂Cu FGMs that had a graded distribution of intermetallic compounds could be produced by this in-situ centrifugal method. Particle size, particle shape and the distribution of intermetallic compounds were controlled by varying the content of the alloy element (Ni, Cu) in the master alloy, the cooling rate in casting and the gravity number. The casting mechanism is explained in terms of the microstructures of the Al-Al ₃Ni and Al-Al₂Cu FGMs fabricated by this method. The corrosion behavior of the FGMs was investigated by electrochemical analysis. Polarization curves of the FGMs in a borate solution were measured by a potentiodynamic method. The presence of Al₂Cu exerted a larger effect on the corrosion behavior of the FGMs than Al₃Ni. Analysis of the polarization curve parameters was effective for evaluating the corrosion resistance of the FGMs.