Thermodynamic optimization of the Cu–Sn and Cu–Nb–Sn systems

Abstract

The Cu–Sn and Cu–Nb–Sn systems were optimized by the means of the CALPHAD (CALculation of PHAse Diagram) technique. The solution phases (liquid, fcc, bcc and bct), gamma and Cu 10Sn 3 were described by the substitutional-solution model. The compounds Cu 3Sn and Cu 41Sn 11 in the Cu–Sn system were treated as (Cu,Sn) m (Cu,Sn) n . The compounds η-Cu 6Sn 5 and η′-Cu 6Sn 5 in the Cu–Sn system were treated as Cu(Cu,Sn)Sn by a three-sublattice model. The compounds Cu 3Sn, Cu 41Sn 11, η-Cu 6Sn 5 and η′-Cu 6Sn 5 in the Cu–Sn system have no solubilities of the third component Nb in the Cu–Nb–Sn system. The compounds Nb 3Sn, Nb 6Sn 5 and NbSn 2 were treated as (Nb,Sn) 3(Nb,Sn), Nb 24Sn 16(Nb,Sn) 4 and (Nb,Sn)(Nb,Sn) 2 in the Nb–Sn system, respectively. The compounds Nb 3Sn, Nb 6Sn 5 and NbSn 2 in the Nb–Sn system were treated as (Cu,Nb,Sn) 3(Nb,Sn), (Cu,Nb) 24Sn 16(Nb,Sn) 4 and (Cu,Nb,Sn)(Nb,Sn) 2 in the Cu–Nb–Sn system, respectively. A self-consistent thermodynamic description of the Cu–Nb–Sn system was obtained.