Vacuum Electromagnetic Levitation Melting and Undercooling of Peritectic Terfenol-D
摘要
For the first time, the undercooling of a magnetostrictive material-a near peritectic Tb0.27Dy0.73Fe1.90 alloy was realized by vacuum electromagnetic levitation melting and 60 K undercooling was obtained. There is one recalescence behavior during solidification of the undercooled melt,which can attribute to the priority precipitation of REFe2 phase instead of REFe3 phase, due to preferential nucleation and higher crystal growth rate of REFe2 phase and the suppression of peritectic reaction. According to the crystal structural characteristics of REFe2 and REFe3, REFe2 is a Laves phase intermetallics with MgCu2 type structure, which has similar polytetrahedral structure with short range ordered structure in undercooled melt and has lower potential barrier for nucleation than that of REFe3,which lead to the preferential nucleation of REFe2 phase directly from the undercooled melt. Also, the similarity of structures between REFe2 phase and undercooled melt leads to higher crystal growth rate of REFe2 phase than that of REFe3.