Improvement of corrosion penetration resistance for aluminum heat exchanger by alloying zirconium

Abstract Corrosion of the aluminum multi-port extrusion (MPE) leads to heat exchanger leakage. Corrosion of the 1xxx series aluminum MPE tubes proceeds continuously along Al13Fe4, which is the precipitation phase of Fe impurity. The continuous corrosion behavior along Al13Fe4 rapidly propagates into the aluminum MPE tube, thereby reducing the penetration life. In this study, Zr was added in order to control the dispersion of Al13Fe4 precipitates in an attempt to improve the corrosion resistance of A1070 aluminum MPE tubes for heat exchangers. The refinement and dispersion of Al13Fe4 phase was controlled by the addition of Zr, which is a highly insoluble element in aluminum. Zr plays a role in increasing nucleation and inhibiting the growth of the surrounding Al13Fe4 phase during the precipitation to Al3Zr phase. As a result, the size of the Al13Fe4 phase became finer and more dispersed, and the continuous corrosion tendency was decreased. Therefore, corrosion propagation of aluminum MPE tube progressed uniformly and penetration was suppressed.