Effect of Ultrasonic Treatment during Solidification on Corrosion Behavior of Mg-3Al-1Zn and Mg-4Zn Magnesium Alloys

Abstract

In this work, effect of ultrasonic treatment during solidification on corrosion behavior of Mg-3Al-1Zn and Mg-4Zn alloy was studied by electrochemical, scanning Kelvin probe force microscopy (SKPFM), hydrogen evolution and micro-zone local corrosion simulation tests. Optical microscopy results revealed the second phases were evidently refined as a result of the ultrasonic treatment during solidification. Potentiodynamic polarization measurements showed better corrosion behavior was obtained in ultrasonically treated alloys with refined second phase. Volta potential mapping indicated higher electrochemical nobility of the β-Mg17Al12 and MgZn2 phase with respect to the α-Mg matrix. The result of micro-zone local corrosion simulation of Mg-3Al-1Zn alloys showed that the discrete, finer β-Mg17Al12 phase in ultrasonic treated alloy had lower anodic average current density than that of the conventionally cast alloy (about 17.6%).

Effects of SnO2 Passive Film and Surface Micro-Galvanic Corrosion on the Corrosion Behavior of as-Extruded Mg-9Li-5Al-xSn Alloys

“…Here, R S is the resistance of the 3.5 wt.% NaCl solution between working and reference electrode and the value was determined by the resistivity of 3.5 wt.% NaCl electrolyte. R ct is the charge transfer resistance, 41 with a greater value of R ct indicating stronger corrosion resistance of the alloy. The CPE dl was constant phase element that is related to electric double layer at the interface between the solution and the metal.…”