Effect of Sc and Zr on Al-6(Mn,Fe) Phase in Al-Mg-Mn Alloys

The effects of Sc and Zr on the shape, size, and number density of Al-6(Mn,Fe) phase in Al-5Mg-0.7Mn alloys were investigated by this article. The results showed that Sc and Zr can form strengthening particles of Al3Sc and Al-3(Sc,Zr), which have the effect of refining grains and modifying the morphology and distribution of Al-6(Mn,Fe) phase. The OM, SEM, and TEM images indicate that with the formation of primary Al3Sc and Al-3(Sc,Zr), the shape of Al-6(Mn,Fe) became more regular, size of Al-6(Mn,Fe) became smaller, and the number density of Al-6(Mn,Fe) increased when compared with base alloy. Zr could motivate the precipitation of primary Al-3(Sc,Zr) and Al-5Mg-0.7Mn-0.2Sc-0.2Zr had better refining effect than Al-5Mg-0.7Mn-0.4Sc. The grain refinement and finely dispersed Al-6(Mn, Fe) phase can improve the mechanical properties such as yield strength and ultimate tensile strength and the corrosion resistance by the results of intergranular corrosion (IGC) also improved.