A new approach to improving the macrosegregation in zirconium-containing magnesium-lithium alloy

摘要

In the preparation process of zirconium-containing magnesium alloy, although zirconium is introduced into alloy by magnesium-zirconium master alloy, the settling of zirconium particles has always been a key problem. In this study, the magnesium-30wt.%zirconium master alloy was added into magnesium-14wt.%lithium-zinc alloy melt in the form of the block (about 20mm) and the particles (about 20m), respectively, and then magnesium-14wt.%lithium-zinc with 0.5wt.% zirconium alloy were prepared using stir-casting process. Macrosegregation of major element (zirconium), microstructure and microhardness at different casting positions were examined to investigate the effect of zirconium addition methods on macrosegregation of magnesium-14wt.%lithium-zinc alloy. The results show that, for the block magnesium-zirconium master alloy addition, there is obvious macrosegregation in alloy ingots, the zirconium contents at the top position of ingot are higher than that at the bottom by nearly 200%. The method of particles master alloy addition can effectively improve macrosegregation, the difference in zirconium contents between the top and bottom is less than 16%.