Abstract: The morphology of solid/liquid interface of a directionally solidification process is described by means of fractal analysis,and the relations among the fractal dimension of the solid/liq- uid interface,solidification rate,dendrite arm space and the phosphorus content of the test al- loys have been given.It was found that the increase of the solidification rate and the phos- phorus content of the test alloy will lead to a increase,following the regularity of exponential function,in the fractal dimension of solid/liquid interface.Furthermore,by combining the fractal theory and the thermodynamic principle with the measured results,it has been proved that the fractal dimension is not only a kind of simple geometrical parameter used in des- cribing irregular geometry,but also a state function depending the change of solidification parameters and chemical compositions.

Key words: fractal dimension, solid/liquid interface, solidification rate, phosphorus, superalloy