IFISUR   23398
INSTITUTO DE FISICA DEL SUR
Unidad Ejecutora - UE
artículos
Título:
Ab-initio comparative study of the Cu-In and Cu-Sn intermetallic phases in Cu-In-Sn alloys
Autor/es:
S. RAMOS DE DEBIAGGI; C. DELUQUE TORO; G.F. CABEZA; A. FERNÁNDEZ GUILLERMET
Revista:
JOURNAL OF ALLOYS AND COMPOUNDS
Editorial:
ELSEVIER SCIENCE SA
Referencias:
Lugar: Amsterdam; Año: 2012 vol. 542 p. 280 - 292
ISSN:
0925-8388
Resumen:
The properties of the intermetallic phases (IPs) occurring in the Cu-In-Sn system are a subject of long-standing theoretical and practical interest in connection with the development of lead-free soldering alloys. In particular, recent experimental work has been devoted to characterize the ternary IPs occuring at the interconnection zone in Cu/In-Sn/Cu joints, which form by incorporating In or Sn atoms to the binary compounds stable in the subsystems Cu-Sn and Cu-In, respectively. These findings open up the need for a comparative account of the structural, cohesive and thermodynamic stability properties of the binary IPs occurring in the Cu-In and the Cu-Sn phase diagrams both at low and at high temperatures. The general purpose of the present work is to perform such a comparative study by relying upon systematic density-functional-theory (DFT) calculations. Using the projector augmented wave method and the exchange and correlation functions of Perdew and Wang in the generalized gradient approximation (GGA), as well as the local-density-approximation (LDA) with the Ceperley and Alder exchange and correlation potentials, we determine the lattice-parameters, molar volume, bulk modulus and its pressure derivative, the electronic density of states (DOS) and the energy of formation (EOF) from the elements of the -Cu7In3 (aP40), -Cu9In4 (cP52) and CuIn2 (tI12) compounds of the Cu-In system. Moreover, DFT-GGA calculations were performed for the compounds -Cu4Sn (cF16), -Cu10Sn3 (hP26), -Cu3Sn both in the (oP8) structure and the (oP80) superstructure, ´-Cu6Sn5 (mC44) and -Cu5Sn4  both in the 1 (mP36) and 2 (mC54) structural forms. In addition, the hypothetical structures obtained by replacing In (or Sn) by Sn (or In) are studied, because of their relevance in CALPHAD modeling of the Cu-In-Sn phase diagram. The present results are compared with experimental data and theoretical values from the literature. The work includes a discussion of the composition dependence of the structural and equation-of-state parameters, the electronic DOS, the EOF of the compounds and the differences between the results of the GGA or LDA calculations and the measured values. Besides, various quantities expressing the relative stability of the IPs are introduced and compared with calorimetric data, and with indirect information obtained in a CALPHAD modeling of the phase-stability fields of ternary compounds described by the two-sublattice scheme Cua(In,Sn)b.