Ge‐22 at. %Au/Au bilayer films annealed at various temperatures have been observed by transmission electron microscopy. The as‐deposited bilayer film is composed of crystalline Ge,Au and metastable Ge0.4Au0.6phases. The Au grain size is nonuniform, and no amorphous Ge is observed. During annealing at 60–350 °C, patterns with several wide branches are generated that are different from the dense branching fractals induced by crystallization of amorphous Ge ina‐Ge/Au films. The fractal dimension of the pattern (measured by the box‐counting method) increases with the annealing temperature. The agglomeration of small Au grains to coarse Au grains in the Ge‐Au/Au bilayer film may be the mechanism for the fractal structure formation. ©1995 American Institute of Physics.