Al-Ni alloy films with an Al to Ni atomic ratio greater than 0.79 were prepared via an alternate sputter deposition technique. The formation of the alloy films was attributed to the interdiffusion and reaction between Al and Ni atoms by the adatom substitution. The crystal structures are all in accordance with the equilibrium phase diagram when the Al to Ni atomic ratio is greater than 2.30. The film with Al to Ni atomic ratio 2.30 is composed of Ni2Al3 and NiAl. A complete NiAl film was obtained when the Al to Ni atomic ratio is less than 1.53. The crystal structure of the film was reverted to Ni-Al equilibrium phases when the -100 V substrate bias was applied during deposition. The films with a NiAl structure showed [100] and [110] preferred orientations on the Si and glass substrates, respectively, disregarding the application of bias. The application of substrate bias significantly reduced the O and N contents and prevented the Al from oxidization. However, bias caused an incorporation of Ar and a lowering of Al content in the films was also observed. The decrease in Al content by the application of bias was attributed to the easier sublimation of Al adatoms from the surface than that from the Ni adatoms.