Transmission electron microscopic study of electroless nickel-molybdenum-boron alloy films

The structure of amorphous and crystalline electroless Ni舑Mo舑B films was studied by transmission electron microscopy (TEM). The amorphous film in as-deposited conditions was of a completely disordered state with few crystalline regions. This film crystallized by means of nucleation after 300ŶC annealing; the produced nuclei grew large after 500ŶC annealing. Two crystalline films in the as-deposited state, plated from 0.005 and 0.010 mol dm^-3 Na₂MoO₄ concentration baths, showed different annealing behavior even though they had almost identical Ni and Mo composition. The former contained amorphous-like regions corresponding to an intermediate state between the amorphous and the crystalline. The latter film was so stable against annealing that the structure of small grains was maintained after 500°C annealing.