STRUCTURAL-CHANGE DURING THE AMORPHIZATION PROCESS BY MECHANICAL ALLOYING

A structural change taking place during the amorphization process by mechanical alloying was investigated by a combination of neutron- and X-ray diffraction techniques. In particular, neutron diffraction offers us crucial structural information associated with the transformation from a crystalline to an amorphous state for Ni-V, Cr-N and Se systems. Emphasis is placed on the topological change in the local atomic structure. Octahedral units in the FCC and BCC structures were transformed into tetrahedral units in the crystalline-to-amorphous transition. The N atom is located at the center of the polyhedron formed by six Cr atoms to stabilize an amorphous structure. Amorphous Se, being composed of chain molecules, was formed from trigonal Se by milling.