The principle and development tendency of different directional technologies were expounded. It is a history of improved temperature gradient and promoted cooling rate from the aspect of directional solidification technology evolution

from traditional directional solidification to cold crucible directional solidification

and to soft contact ceramic mold directional solidification

and thereafter to e-lectromagnetic confined directional solidification. Constitutional undercooling

interface stability

and the phase selection and microstructure evolution of pertiectic

monotec-tic and eutectic binary alloy systems were reviewed briefly.