Microstructure and corrosion resistance of anodized Mg-9 mass % Li-1 mass % Zn alloy

Abstract

This research used pulse and direct current methods to perform surface anodizing treatment of Mg-9 mass%Li-1 mass%Zn alloy (LZ91). The anodic films were analyzed with electrochemical impedance spectroscopy (EIS) for corrosion resistance. The impedance measurements show that the resistance value of anodic films made by pulse current to be 100 K Ω a: 2 at 2 × 10 -2 A/m2 and those made by direct current anodic films to be 65 KΩ2 at 2 × 10-2 A/m2. It reveals that pulse current makes better anodic films than direct current. There were two layers in the anodic films that were verified from the EIS phase angle diagram in which three time constants existed. The structure of the film was analyzed by a FE-SEM, and the microstructure observation showed that the anodic film consists of porous and barrier layers. © 2008 The Japan Institute of Metals.