Thermodynamic properties of indium-copper alloys

The thermodynamical properties of hard alloys of In-Cu of the composition 8.6 to 39.0 at% of In at 382 deg to 580 deg C have been studied by the e.m.f. technique. Making use of the literature value of Δ Hsub(f) (enthalpy) at 450 deg C and the data the present investigation, Δ Hsub(f), Δ Ssub(f) (entropy) and Δ Gsub(f) (Gibbs energy) have been calculated for the intermediate phases at 450 and 500 deg C. Thus, at a 39% content of In in the alloy and at a temperature of 773 deg K Δ G=1.08+-0.12 Kcal/gxat; Δ H=1.97+-0.04 Kcal/gxat; and Δ S=-1.16+-0.14 cal/degxgxat. The phase transitions in hard alloys of different compositions have been investigated