The main purpose of this work was to investigate the possibility of solid state amorphization of Ni-B crystal powder. A Ni-B alloy powder was obtained by mechanical alloying of Ni and B powder using a conventional ball milling machine.X-ray diffraction and EXAFS measurements were made for the mechanically alloyed samples as a function of milling time. An amorphization reaction was observed in Ni 64 B 36 at 400 h of milling time. The long range order of the crystalline Ni phase diminished with an increase of solution of B into the Ni matrix. This suggests that the solution of B atoms into the Ni crystalline phase, forced by mechanical alloying, plays an important role in the crystalamorphous transformation.