Real time imaging on dendrite morphology evolution during alloy solidification under electric field

Abstract

The dynamic dendrites growth of metallic alloy during the solidification can not be in-situ observed since the metallic alloy is in optically opaque. It is also not possible to in-situ study the influence of electric current on dendrites growth behaviour. By using synchrotron radiation imaging technique, the evolution of dendrite morphology under an electric current is observed. Results indicate that the direct current can significantly suppress the dendrites growth and the dendrite tip tends to be round from sharp. Increasing the current intensity, the dendrite tip splits due to the current crowding and solute pileup around the round tip. The pulsed electric current can significantly enhance the solidification rate and refine the primary and secondary dendrite arm spaces because of the thermal and mechanical shock around solid/liquid interface.