Evaluation of Partial Structure Factors in the Small Q-Region with Amorphous Ni80P20 by Neutron Diffraction Using Isotopic Substitution

Abstract

Amorphous Ni80P20-alloys were produced under He-atmosphere by the melt spin technique. With three specimens produced from P with natNi, 62Ni and 0Ni elastic scattering expriments were performed using neutrons with l = 5.4 Å in the Q-region 6 · 10−3 Å−1 ≦ Q ≦ 2.7 · 10−1 Å−1 . The measured intensities were corrected for absorption and background, desmeared, and normalized. The partial Bhatia Thornton structure factors SNN, SCC, and SNC w e r e evaluated and allowed the following conclusions: The a-Ni80P20-alloy contains regions with radii of about 6.5 Å caused by concentration fluctuations. A method is presented which allows to determine the composition of the regions and the total content of regions within the specimen. In the small Q-region (6 · 10−3 Å−1 ≦ Q ≦ 4 · 10−2 Å−1) the run of the partial structure factors is proportional to Q−3caused by concentration- and density-fluctuations. From the partial Fourier transforms follows a slight anisotropy concerning the chemical arrangement with correlation lengths elongated along the ribbon direction.