DIRECTIONAL SOLIDIFICATION OF UNDERCOOLED MELT

The directional solidification of highly undercooled single phase allo y is put forward. In contrast with the conventional directional solidi fication, it occurs under a negative temperature gradient at the solid /liquid interface. The essential condition for this process is that th e thermal diffusion in liquid plays a dominant role in the crystal gro wth. An experiment on Cu-30at. %Ni alloy was conducted, and a directio nal solidification structure consisting of a single crystal was obtain ed in the undercooling range of 105-155 K.