The thermodynamics of Bi-In-Sn lead-free solder alloys has been studied by two different experimental techniques: torsion-effusion and differential scanning calorimetry. The results show that this ternary system at fixed Bi composition, X-Bi = 0.20, and 565 K behaves as a non-ideal system with exothermic Delta(mix) H-T(0) passing through a minimum at X-In = 0.58 and X-sn = 0.22. In the whole range of the quantity X-Sn/(X-Sn + X-In) T and at 1050 K the average value of the bismuth activity is 0.14 +/- 0.02 which implies an average activity coefficient of Bi equal to 0.70 +/- 0.01. The Bi activity in ternary alloys at 1000 K with variable X-Bi and fixed ratio rho = X-Sn/X-In = 0.85 has been measured. The excess integral free energy change for the mixing, Delta(mix) G(T)(0) (xs), has also been evaluated by making use of both the torsion-effusion experimental and literature data T for Bi-Sn and Bi-In binary systems. Under these conditions, the ternary system is not a regular solution and the entropy contribution to the free energy of mixing is dominating the Gibbs energy. (C) 2006 Elsevier Ltd. All rights reserved.
Bismuth activity in lead-free solder Bi-In-Sn alloys / Brunetti, B; Gozzi, Daniele; Iervolino, M; Piacente, Vincenzo; Zanicchi, G; Parodi, N; Borzone, G.. - In: CALPHAD. - ISSN 0364-5916. - STAMPA. - 30:4(2006), pp. 431-442. [10.1016/j.calphad.2006.07.003]
Bismuth activity in lead-free solder Bi-In-Sn alloys
GOZZI, Daniele;PIACENTE, Vincenzo;
2006
Abstract
The thermodynamics of Bi-In-Sn lead-free solder alloys has been studied by two different experimental techniques: torsion-effusion and differential scanning calorimetry. The results show that this ternary system at fixed Bi composition, X-Bi = 0.20, and 565 K behaves as a non-ideal system with exothermic Delta(mix) H-T(0) passing through a minimum at X-In = 0.58 and X-sn = 0.22. In the whole range of the quantity X-Sn/(X-Sn + X-In) T and at 1050 K the average value of the bismuth activity is 0.14 +/- 0.02 which implies an average activity coefficient of Bi equal to 0.70 +/- 0.01. The Bi activity in ternary alloys at 1000 K with variable X-Bi and fixed ratio rho = X-Sn/X-In = 0.85 has been measured. The excess integral free energy change for the mixing, Delta(mix) G(T)(0) (xs), has also been evaluated by making use of both the torsion-effusion experimental and literature data T for Bi-Sn and Bi-In binary systems. Under these conditions, the ternary system is not a regular solution and the entropy contribution to the free energy of mixing is dominating the Gibbs energy. (C) 2006 Elsevier Ltd. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
