Characterizations on the instantaneously formed Ni-containing intermetallics in magnesium alloys

Instantaneous reactions of Al, Mn, Zn, Zr and Y with Ni by mixing the prepared Mg-8Al-0.4Mn, Mg-6Zn-2Y-0.5Zr and Mg-0.6Ni melts were investigated in this work to reveal the underlying mechanisms of their effects on the removal of Ni impurity. The results indicate three Ni-containing intermetallics, namely Al4NiY, Al4Ni(Y,Zr) and Al31Ni2Mn6. The former two phases present lath-like and have a relatively larger size (> 20 mu m in length) than the latest one which is granular with the diameter of similar to 120 nm. This illustrates that Al and Y(/Zr) can efficiently remove Ni by forming Al4NiY or Al4Ni(Y,Zr) which would precipitate to the bottom of the melt. Furthermore, adding Y into Mg-Al based alloys can simultaneously remove Fe and Ni, which contributes their excellent corrosion resistance. Finally, this paper proposes two methods helped to efficiently remove Ni for both Mg-Al based alloys and Al-free Mg alloys, and both of them are also benefit to improve alloys' strength.(c) 2022 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CCBY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)