Effect of Zr Addition on the Corrosion Behavior of Extruded Mg Alloys in NaCl Solution

Abstract

The effect of Zr addition on the corrosion behavior of an extruded Mg-10Gd-1Zn alloy (GZ101) in 3.5 mass% NaCl solution was investigated by electrochemical and immersion tests in 3.5% NaCl solution. The addition of 1 mass% Zr to GZ101 (to afford GZ101-1Zr) decreased the fraction of 14H (number of stacking layers and H-Hexahedral structure) and lamellar long period stacking ordered (LPSO) phases across the α-Mg matrix and increased the fraction of the X-phase (Mg₁₂GdZn) formed at grain boundaries. Extruded GZ101-1Zr exhibited a significantly smaller corrosion rate than extruded GZ101 (0.13 vs. 2.11 mm∙year⁻¹) due to containing less 14H/lamellar LPSO phases (detrimental to corrosion resistance) and featuring a noble prismatic texture in the extrusion direction.