The role of size effect on the bulk properties of copper-tin liquid alloys

Abstract

A statistical mechanics model based on complex formation and a Flory’s approximate model have been used to theoretically
investigate the effect of size difference on the bulk properties of copper-tin liquid alloys, by computing concentration
fluctuations in the long wavelength limit, diffusivity, free energy of mixing, integral entropy of mixing and Warren-Cowley
short range order parameter of Cu-Sn liquid alloys at 1400K. The results indicate that although, the chemical interactions
between copper and tin atoms are quite weak in the entire Cu concentration in the alloys, size effect increase the degree
of the interactions in the composition rangeCcu ? 0.75 and reduces the tendency for heterocoordination in the composition
range 0.60 ? Ccu ? 0.90. Also, the results reveal further that size effect significantly increase the magnitude of the integral
entropy of mixing of Cu-Sn liquid alloys in the composition range Ccu ? 0.30 and that the contributions of ideal entropy
of mixing, temperature dependent interchange energy and size difference to the integral entropy of mixing are quite
significant and complementary. The study further indicate that Flory’s approximate model, possibly has significant limitation.