FORMATION OF AMORPHOUS AL-CR AND AL-MN ALLOY-FILMS BY RF-SPUTTERING

A new type of amorphous alloy, formed in the limited composition range of about 80-90 at.% Al (AlCr) and 70-90 at.% Al (AlMn) was produced by fr sputtering under Ar atmosphere. The existence of the amorphous phase was confirmed by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. The formation of the amorphous phase is discussed in association with the intermetallic compounds (CrAl7, Mn4Al11, MnAl6, etc.) having crystallographically complex structure, which have nearly the same composition as the amorphous phase. A weak X-ray scattering halo is observed at the diffraction angle lower than of the strongest halo which characterizes the amorphous structure. The weak scattering halo, which is generated by an X-ray interference effect, is considered to be correlated to the small clusters in which a transition metal atom coordinates several Al atoms. The crystallization temperatures of the amorphous alloys are about 400 and 370°C for AlCr and AlMn samples, respectively. © 1990.