SANS characterization of particle dispersions in W-Ti and W-V alloys

SEM analyses of W-Ti and W-V alloys produced by a powder metallurgy route have revealed the presence of Ti or V pools with different sizes and shapes. The larger pools have sizes between ~ 0.3 and several microns and are embedded between the matrix grains. The smaller Ti-rich (V-rich) particles, with sizes below ~ 0.3 μm, are spherical and are dispersed inside the matrix grains. The characteristics of the second phase nanoparticles have been studied using the SANS technique. The scattering curves have been analyzed in terms of a polydisperse particle system following the Beaucage approach, and the maximum entropy method to obtain the particle size distributions. Beaucage analyses suggest the presence of two particle populations, characterized by radii of gyration from 50 to 80 Å (population I) and between 650 and 760 Å (population II). The volume distribution obtained by the maximum entropy approach reveals a prominent peak with particle diameter of 60 Å and ~ 70 Å for the W-Ti and W-V alloys, respectively. Secondary peaks in the size range 100-300 Å could be associated with the particle population with the larger radius of gyration.