Effect of aging on corrosion and discharge performance of AZ63-1.5RE alloy as anode in magnesium-dissolved oxygen seawater batteries

Abstract

This study aims to understand how aging treatment affects corrosion resistance and discharge performance of AZ63-1.5 rare earth mischmetals (AZ63-1.5RE) alloy in low-power dissolved oxygen seawater batteries. Solutionizing and aging treatment at 180 °C, 210 °C, and 240 °C for 16 h, 20 h, and 24 h is used to investigate the effects of heat treatment on corrosion and discharge performance. An XRD pattern of alloys after solutionizing and aging indicates a change in crystalline orientation and an increase in Mg phases proportion. A reduction in self-corrosion of alloys is achieved through solutionizing and aging. With solutionizing and aging of the alloys, their discharge potentials is shifted to more negative values by about 0.01–0.02 V. The anodic efficiency also is improved significantly from 53.89% for the as-cast alloy to 67.55% for the aged alloy at 210 °C for 20 h. Following 24 h of discharge, the aged alloy at 210 °C demonstrated the highest polarization resistance. The favorable corrosion performance can be attributed to grain refinement of the β-Mg17Al12 phase, the increased contribution of the Al-RE corrosion-resistant phase, the low contribution of the layered phase in the matrix, and the formation of dense discharge products on the surface.