| Compared with other engineering structural materials such as aluminum and titanium,the application of magnesium and its alloys has been greatly limited in the aerospace,automotive and electron industries because of their lower absolute strength and poor corrosion resistance.Therefore,there is an urgent need to develop a new type of magnesium alloy that combines excellent mechanical properties and corrosion resistance.According to the previous research results and literature investigation,we found that Sc element has great potential to improve the mechanical properties and corrosion resistance of magnesium.In this paper,element Sc was added into pure magnesium and Mg-Sc alloy Mg-2wt.%Sc,Mg-5wt.%Sc,Mg-10wt.%Sc and Mg-15wt.%Sc was prepared.The microstructure,mechanical properties and corrosion resistance of pure Mg and Mg-Sc alloy were investigated by optical microscopy,scanning electron microscopy,X-ray diffraction,electrochemical workstation,etc.The results of microstructure analysis have shown that the addition of Sc resulted in the grain refinement of magnesium and the grain size decreased with the increase of Sc content.Mg-2wt.%Sc,Mg-5wt.%Sc,Mg-10wt.%Sc were monophase and MgSc second phase appeared in Mg-15wt.%Sc.The distribution of Sc element in the alloy was not uniform and formed"Sc-rich part"and"Mg-rich part".The results of mechanical properties analysis have shown that the addition of Sc increased mechanical properties of Mg,and the yield strength,tensile strength and hardness increased with the increase of Sc content,reaching the highest at Mg-15wt.%Sc.The yield strength,tensile strength and hardness were 125 MPa,152 MPa and 62.1 HV respectively,which increased465.6%,103.5%and 125.0%relative to pure Mg.The elongation of Mg-Sc alloy increased at first and then decreased,and the elongation of Mg-10wt.%Sc is the largest,which is 10.3%and increased 119.1%relative to pure Mg.The change of fracture morphology corresponded to the change of the elongation.The results of corrosion analysis have shown that the corrosion rates of the four components of Mg-Sc alloy were lower than those of pure Mg and the corrosion resistance of Mg-Sc alloy was better than pure Mg,among which Mg-5wt.%Sc showed the best corrosion performance.The addition of Sc increased the potential of magnesium and suppressed the cathodic and anodic reactions.The corrosion product of Mg-Sc alloy contained Sc2O3,whose PB ratio is>1 and insoluble in water,which was an important factor to improve the corrosion resistance of Mg. |
