In this study, the effect of heat treatment on the corrosion properties of Mg-Zn-RE-xCa alloy (x = 0, 2.5) was investigated. These alloys were produced using an argon atmosphere casting process and then subjected to vacuum conditions at 400 C for 6 hours under solid solution treatment and quenching in water. The microstructure and fuzzy analysis of heat treatment alloys using optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) were investigated. Immersion, polarization, impedance, and pH changes test were performed to study alloy corrosion behavior. The results showed that in heat treated samples, the values of secondary phases IM1 (Ca3MgxZn15-x) (4.6 ≤ x ≤ 12) and Mg2Ca increased with increasing calcium content. However, the amount of these phases is reduced by dissolution and quenching in water. The corrosion density of alloy is reduced by adding 2.5% calcium from 488.4 to 315 μA / cm2, which decreases to 126.5 μA / cm2 after 6 hours of heat treatment, indicating improved corrosion resistance of the alloy after heat treatment. Manuscript profile