Effect of rolling and heat treatment on microstructure and electrochemical properties of Mg-Hg-Ga alloy

Microstructure and electrochemical properties of Mg-Hg-Ga alloy in as-cast, homogenization, rolling states were investigated by means of SEM, XRD and electrochemical methods. The annealing treatments at 150-300°C were carried out for the alloy after rolling and effect of annealing temperature on microstructure and electrochemical properties of the alloy were examined. The results showed that the homogenizing at 400°C for 24 h eliminated the alloying elements segregation of the as-cast Mg-Hg-Ga alloy and improved its electrochemical properties. When annealing temperature increased to 250°C, the electrochemical activity of the Mg-Hg-Ga alloy increased to the maximum value and then decreased when the temperature exceeded 250°C. While the corrosion resistance of the Mg-Hg-Ga alloy decreased with increase of annealing temperature, and the corrosion current density increased from 3.525 × 10 -4 A/cm 2 to 2.438 × 10 -3 A/cm 2 when the annealing temperature increased from 150°C to 300°C. This is related to the increase of amount and size of dispersed spherical precipitates in the alloy annealed at higher temperatures.