RADIAL DISTRIBUTION FUNCTIONS OF (METALLIC GLASSES) IRON(40) NITROGEN(40) PHOSPHORUS(14) BORON(6) AND IRON(30) NITROGEN(50) PHOSPHORUS(14) BORON(6)

Although many of the physical properties of the two metallic glasses, Fe(,40)Ni(,40)P(,14)B(,6) and Fe(,30)Ni(,50)P(,14)B(,6) have been measured and published in the literature, the structural properties of these two materials have not yet been determined. The atomic structure of amorphous materials is characterized by the reduced radial distribution function and the radial distribution function (RDF). These functions are determined by measuring the scattering of x-rays, neutrons, or electrons from the materials. For this research, the x-ray scattering from Fe(,40)Ni(,40)P(,14)B(,6) and Fe(,30)Ni(,50)P(,4)B(,6) was measured for values of the scattering parameters, K, from 1 to 17. The measurements were made with a two-theta diffractometer using MoK(alpha) radiation. The data were corrected for absorption, polarization, and multiple scattering. Theoretical Compton scattering corrections were applied. The interference function which is the corrected scattering intensity as a function of K was Fourier transformed, to obtain the reduced radial distribution function. The location of the first peak of this function gives the nearest neighbor distance as r(,1) = 2.54 angstroms, for both metallic glasses. This value is in good agreement with published results on related amorphous materials. The locations of the second and third peaks, which are not well resolved, were determined to be r(,2) = 4.18 and r(,3) = 4.80 for both materials. For comparison to dense random packing of hard spheres (DRPHS) models, r(,2) and r(,3) are expressed in terms of sphere diameters by dividing by r(,1) giving r(,2)/r(,1) = 1.65 and r(,3)/r(,1) = 1.89. These values are in very good agreement with the DRPHS model of Sadoc, Dixmier, and Guinier. The measured densities of Fe(,40)Ni(,40)P(,14)B(,6) and Fe(,30)Ni(,50)P(,14)B(,6) were 7.56 gm/cm('3) and 7.62 gm/cm('3), respectively. These densities and the reduced radial distribution functions were used to calculate the radial distribution functions. The coordination number, CN, which gives the average number of nearest neighbor atoms was calculated for each RDF. The values of CN for Fe(,40)Ni(,40)P(,14)B(,6) and Fe(,30)Ni(,50)P(,14)B(,6) were 11.7 and 11.4, respectively.