NITROGEN INDUCED AMORPHIZATION OBSERVED BY NEUTRON-DIFFRACTION IN THE CR-FE SYSTEM

Mechanical alloying (MA) of Cr0.7Fe0.3 and pure Cr powders were carried out under Ar and N-2 gas atmospheres. Amorphization has been observed in the MA process under a N-2 gas atmosphere, while MA under an Ar gas atmosphere produces a BCC solid solution. Structural transformation from the crystalline to amorphous state was investigated using the neutron diffraction technique. During the amorphization, the BCC crystal structure built up from octahedral units was destroyed and modified. The neutron diffraction measurement revealed that a nitrogen atom is situated at a center of the polyhedron formed by six metal atoms.