Effect of Mn on microstructure, mechanical properties, and corrosion behaviour of Mg-Ni alloys

Previous research on Mg-Ni alloys focused on the mechanical characteristics and damping behaviour in the presence of Zn and rare Earth elements. There has not been much research on the Mg-Ni-Mn alloy’s microstructure, mechanical properties, and corrosion behaviour. The present research work fulfills this gap by concentrating on the microstructure, mechanical, and corrosion characteristics of Mg-Ni-Mn alloys. Here, different Mg-Ni-Mn alloys were developed by varying the nickel and manganese content. The microstructure of the developed alloys was studied using an optical microscope and scanning electron microscope. Ultimate tensile strength and microhardness of all alloys were performed on a tensometer (room temperature), and Vickers hardness tester respectively. The corrosion rate of Mg-Ni and Mg-Ni-Mn alloys was measured at 3.5 wt% NaCl solution by immersion test. The result shows that the nickel and manganese presence refine the grain size of magnesium. XRD analysis confirmed the presence of α-Mg and Mg2Ni phases in Mg-Ni alloys. Along with these phases, the Mn phase was observed in Mg-Ni-Mn alloys. Mechanical properties such as ultimate tensile strength and hardness of pure magnesium were increased in the presence of Ni and Mn. However, the presence of manganese in Mg-Ni alloy shows an adverse effect on corrosion behaviour. The corrosion rate of the Mg-Ni alloy was accelerated in the presence of manganese.