An investigation of the impacts of non-isothermal aging on the microstructures and corrosion of WE43 Mg alloy

Abstract

The impacts of non-isothermal aging treatment (NIA) on the microstructure and corrosion resistance of WE43 magnesium alloy was examined through weight loss experiments, hydrogen evolution experiments, electrochemical assessments, three-dimensional microscopy, potential surface measurements, and microscopic analyses. The NIA modified the WE43 magnesium alloy by decreasing the precipitation-free zone (PFZ) and disrupting the continuous arrangement of precipitates along the grain boundaries. The Volta potential at the grain boundaries of NAI specimens (with respect to the matrix) was −35 mV, significantly lower than −110 mV in T6 specimens. Due to the effect of micro-galvanic corrosion between the grain boundaries and the grain interiors couple, T6 specimens exhibited significant grain boundary corrosion. They showed grooves with a maximum depth of about 13 μm and a width of about 30 μm after the immersion test. The NAI specimens have shallower grooves at the grain boundary. The corrosion rate of the three specimens was ranked as T4> T6> NAI.

Keywords

• WE43 Mg alloy
• Non-isothermal ageing
• Heat treatment
• Corrosion rate