Stability of solid/liquid interface of Pb-80wtSn alloy under direct current during directional solidification

摘要

The effect of medium-density current on the morphological stability of S/L interface of Pb-80wt%Sn alloy during directional solidification was investigated. The results indicated that both the DC of positive and negative 200 Acm~(-2) could decrease the critical growth rate of cellular/dendrite transition and minish the range of growth rate of cellular crystal. DC accelerated the microstructure transition from cellular crystal to dendrite crystal at the same pulling rate. Furthermore, the dendrite crystal was refined by positive and negative DC at high pulling rate. The effect of direction of DC to the microstructure transition could be neglected. In conclusion, the positive and negative 200 Acm~(-2) decreased the stability of solid/liquid interface of Pb-80% Sn alloy, and the lower the pulling rate was applied, the more obviously DC affected the microstructure.