Atomic Structure of Amorphous Metallic Ni81B19

The three partial Faber Ziman structure factors as well as the Bhatia Thornton structure factors of the metallic glass Ni81B19 were evaluated by neutron diffraction experiments using the isotopic substitution method. In one of the investigated specimens the isotopic composition of the components was adjusted in such a way as to make it possible to measure directly with one diffraction experiment the correlation between the metalloid atoms. From the three partial pair correlation functions the atomic distances and the partial coordination numbers are determined. The results demonstrate the strong chemical ordering in amorphous Ni81B19. Particularly the distance correlation between the boron atoms turned out to be very pronounced. The experimental results agree with the main features of a geometrical packing model of soft spheres.