LAUSR

This paper is about the three types of bcc Nbss solid solution, namely normal Nbss, Nbss rich in Ti and Nbss with no Si that are observed in multi-component Nb silicide based alloys of Nb-Si-TM-RM-X (TM = Cr, Hf, Ti, V, RM = Mo, Ta, W, X = Al, B, Ge, Sn) systems. The entropy (ΔSmix) and enthalpy (ΔHmix) of mixing, atomic size difference (δ), electronegativity difference (Δχ), valence electron concentration (VEC) and the parameter Q = Tm ΔSmix/|ΔHmix| were calculated for fifty four solid solutions. The values of these parameters were −2 0.179 had no B, Ta and V and the solid solutions with no W had Δχ 5) and the Nbss with no Si (δ < 5). The formation of Ti rich Nbss and Nbss with no Si was attributed to the partitioning of Mo, Ti and W.