AbstractA molten Pd82Si18 alloy, free of potent heterophase impurities and enclosed in a fused silica tube of conical shape, was quenched in water. Four regions classified according to their microstructures can be distinguished. They are: region I, amorphous; region II, a mixture of an amorphous nanostructure and a nanocrystal; region III, a mixture of two kinds of nanocrystals; region IV, spinodal networks; and region V, conventional eutectic structure. The detailed microstructures in each region are discussed.