THE NI-NI PARTIAL STRUCTURE IN NI-V ALLOY SYSTEM OBSERVED BY NEUTRON-SCATTERING DURING MECHANICAL ALLOYING AMORPHIZATION PROCESS

The alternation of the partial NiNi correlation of Ni40V60 powders in amorphization process by MA was directly observed by neutron diffraction, because the coherent neutron scattering length of a V atom is very small in comparison with that of a Ni atom. Most of peaks attributed to the Ni atom positron of FCC crystal in RDF decrease and broaden gradually to be superimposed on the broad haro originating from the amorphous structure, but the peaks of the 2nd and 5th NiNi neighbor positions observed within 7 A distance drastically decrease and disappear with increasing MA time. The result indicates that octahedral units forming FCC structure decrease with increasing MA time and the amorphous structure is mainly composed of tetrahedral units. © 1990.