Transmission of Monoenergetic Slow Neutrons through Solid Solutions and Mechanical Mixtures of TiC and WC

TiC and WC form continuous substitutional solid solutions at least up to 25 percent TiC+75 percent WC by weight when heated to 4000°F, TiC being the solvent and WC the solute. Total neutron scattering cross sections of a series of finely powdered solid solutions and corresponding mechanical mixtures of the two carbides were determined as a function of the mole percent of WC from the measured transmission of monoenergetic neutrons with energies 0.08138, 0.03479, 0.02056, and 0.01526 ev or wave-lengths λ=1.004A, λ=1.536A, λ=1.998A and λ=2.319A, respectively. The cross sections of both the solutions and the mixtures increase with increasing mole percent of WC. For mixtures they are the same as the additive cross sections, each constituent scattering independently of the other. They are analogous to x-ray scattering for the mixtures in which each constituent gives its own diffraction pattern and the patterns of the two constituents are superimposed. The neutron cross sections of solid solutions are lower than those of the mixtures at low percentages of WC but increase rapidly with the concentration of the solute molecules. They appear to be sensitive both to the structure of the solvent and the concentration of the substituting atoms.