Study on localized corrosion behavior of hot extrusion deformed GW103K magnesium alloy

Abstract

This study investigated the corrosion behavior in the core and at the edge of the cross-section of an extruded GW103K (Mg–10Gd–3Y–0.4Zr) alloy. Equivalent stress and strain were modeled using finite element simulations. The stress and strain in the core were lower than those at the edge. The microstructure, corrosion morphology, and grain orientation of the alloy were examined using optical microscopy, scanning electron microscopy, and electron backscatter diffraction, respectively. The results showed that most grains in the core exhibited a basal plane orientation and lower surface energy, whereas those at the edge exhibited cylindrical orientations. Hydrogen evolution experiments and electrochemical tests showed that the corrosion resistance in the core was higher than that at the edge. Scanning Kelvin probe force microscopy measurements of the surface potential distribution in the cross-section revealed a large potential difference between the second-phase particles at the edge and the matrix, with obvious galvanic corrosion. The alloy core exhibited low stress and a higher content of grains with basal plane orientation, along with a small potential difference between the second-phase particles and the matrix. Thus, the corrosion resistance in the core was higher than that at the edge.