Effect of steady ampoule rotation on axial segregation in vertical Bridgman growth of Terfenol-D

摘要

In Bridgman growth of Terfenol-D, the axial macrosegregation can occur due to the compositional in-homogeneity of initial melt. Since this melt segregation was hard to diminish by buoyant or solutal convection, we have introduced the steady ampoule rotation technique to change the convection pattern and investigated the effect of rotation speed and growth rate. The results showed that ampoule rotation changed the axial segregation and effectively diminished the segregation at 60 rpm and 25 μm/s growth rate. The degree of the axial segregation was affected both by the growth rate and rotation speed, and could be described as a function of a combined variable of rotation speed/growth rate.