DENDRITIC GROWTH VELOCITIES IN UNDERCOOLED MELTS OF B20-TYPEINTERMETALLIC COMPOUNDS

摘要

Dendritic growth velocities in undercooled melts of B20-type intermetallic compounds FeSi, CoSi,(Fe_(0.5)Co_(0.5))Si, Fe(Si_(0.5)Ge_(0.5))and(Fe_(0.5)Co_(0.5))(Si_(0.5)Ge_(0.5))were measured using a combination of the glass fluxing technique with a high-speed camera. The measured data show that partial replacement of element Co for element Fe produces a weak effect on the dendritic growth velocities of the ternary or quaternary compounds, whereas partial replacement of element Ge for element Si leads to a drastic reduction of the growth velocities. The measured data also show that the dendritic growth velocities of the(Fe_(0.5)Co_(0.5))(Si_(0.5)Ge_(0.5))intermetallic compound rise abruptly upon reaching a critical undercooling of 245K due to complete disorder trapping. The results were discussed with the respect to the effects of elemental substitutions on interface kinetics during dendritic growth of the B20-type intermetallic compounds.