The effect of cross-section geometry of castings on dendrite evolution in Mg-Gd alloys by in situ X-ray radiography

The solidification process of Mg-15Gd(wt.%)alloys with different cross-section geometry is investigated in situ by synchrotron radiation imaging technology. The evolution of dendrites, including the nucleation and growth processes, has been recorded and analyzed for magnesium alloys with different cross-section geometry. It is shown that the cross-section geometry of the samples has significant effect on the number of dendrites, the growth rate of dendrites, and the solute distribution. We find that the cross-sectional change does not conducive to the nucleation of dendrites. The variable cross-section facilitates the growth of dendrites while the T-type section inhibits the growth of dendrites. The solute in the variable cross-section sample (VSS) is enriched at the shoulder while the solute in the T-type section sample (TSS) tends to concentrate at the bottom of the boss. Meanwhile, the fracture and drift of dendrites in VSS and TSS are observed. As a result, the grain fragments tend to form stray crystals

Automated summary

The solidification process of Mg-15Gd alloys with different cross-section geometry was investigated using synchrotron radiation imaging technology. The evolution of dendrites, including nucleation and growth processes, was recorded and analyzed. The results show that the cross-section geometry of the samples has a significant effect on the number and growth rate of dendrites, as well as solute distribution.