Tungsten-iron alloy was produced by electrodeposition. The electrodeposited alloy (15 at.% W) possesses a two-phase composite microstructure, containing a nanocrystalline phase of distorted BCC structure with a grain size between 50 to 150 nm and an amorphous phase as the matrix. TEM in-situ annealing revealed that this composite structure was stable up to 650 degrees C. When tungsten content was doubled, the deposited alloy became amorphous.