MECHANICAL ALLOYING OF NI-NB IN DIFFERENT ATMOSPHERES

The formation of Ni-Nb alloys prepared by mechanical alloying (MA) in different atmospheric conditions was examined by X-ray diffraction. Ba ll milling of elemental Ni and Nb powders under an argon atmosphere fo r alloys with Nb contents up to 15 at.% forms a supersaturated solid s olution on the base of Ni. Amorphous alloys are formed if the Nb conte nt is more than 20 at.%. The interaction of metallic powders Ni and Nb was absent and a b.c.c. phase was formed for all compositions up to p ure Nb, when MA of Ni-Nb powders was performed in the presence of wate r, alcohol or acetone in Ar and air atmospheres. This phase, identifie d as the interstitial phase of oxygen in niobium, has the lattice para meter a=3.390 Angstrom and an O content of about 34 at.%.