Corrosion resistance and microstructure of 3D printed magnesium alloy regulated by heat treatment

• Heat treatment effectively improves the corrosion resistance of 3D printed magnesium alloys. • Reduction of micro galvanic corrosion and formation of protective surface film during corrosion contribute to the enhanced corrosion resistance, which can be regulated by heat treatment. Corrosion behavior of 3D printed Mg-3Nd-1Gd-0.2Zn alloy in three states, namely 3D print, 3D print-T4, and 3D print-T6, was investigated. The 3D printed alloys were characterized using SEM, XRD, and other techniques to demonstrate an improved corrosion resistance achieved through heat treatment. Complete dissolution of Mg 41 Nd 5 phase in 3D printed magnesium (Mg) alloy resulted in a more uniform corrosion morphology. It improves corrosion resistance of the alloy. Moreover, reduction in surface potential of Mg 3 (Nd,Gd) phase after heat treatment contributes to deceleration of galvanic corrosion, while the absence of Mg 41 Nd 5 after heat treatment slows down localized corrosion. Compared to the 3D print state, T4 and T6 treated alloys exhibit the formation of protective oxide films during corrosion. Meanwhile, after heat treatment, T4 and T6 alloys have thick and smooth corrosion product films, which may enhance corrosion resistance. In general, corrosion resistance of Mg-3Nd-1Gd-0.2Zn alloy is improved after heat treatment.