Variations of the Partial Short Range Order Structure of Amorphous Ni32Pd52P16 During Relaxation Using Neutron Diffraction and Isotopic Substitution

Abstract

Melt spun amorphous Ni32Pd52P16 specimens were produced using natNi, the isotope 60Ni, and an isotopic mixture ∅Ni with zero-scattering length. The specimens were heat treated for two hours at 496, 533, 570, and 607 K, respectively, and investigated by neutron diffraction. The Faber-Ziman structure factors as well as the total pair correlation functions show rather large effects caused by the relaxation procedure. By convenient combination of the total functions conclusions on the behaviour of the Ni-Ni, Ni-Pd, Ni-P, Pd-Ni, Pd-Pd, Pd-P, P-Ni, and P-Pd partial coordina­tion numbers and atomic distances during the relaxation procedure are obtained. Relaxation has no detectable influence on the nearest neighbourhood but leads to variations in the region of the second Ni-Ni coordination sphere (3.7 Å ≦ R ≦ 5.7 Å) with the main effect that after heat treatment at 607 K, 2 h, the second Ni-Ni coordination sphere is subdivided into three distinct subspheres. It is suggested that the relaxation process mainly involves the redistribution of bond angles.