NITROGEN INDUCED AMORPHIZATION OBSERVED BY NEUTRON-DIFFRACTION IN THECR-FE SYSTEM

Mechanical alloying (MA) of Cr0.7Fe0.3 and pure Cr powders were carrie d out under Ar and N-2 gas atmospheres. Amorphization has been observe d in the MA process under a N-2 gas atmosphere, while MA under an Ar g as atmosphere produces a BCC solid solution. Structural transformation from the crystalline to amorphous state was investigated using the ne utron 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 s ituated at a center of the polyhedron formed by six metal atoms.