Ab-initio study of Cu-In and Cu-Sn intermetallic phases. Calculation of energy parameters involved in the thermodynamic assessment of the Cu-In-Sn system using sublattice models

S. RAMOS DE DEBIAGGI; G.F. CABEZA; A. FERNÁNDEZ GUILLERMET

Buenos Aires

Congreso; At the Frontiers of Condensed Matter V; 2010

CNEA - UNSAM

The search for new lead-free soldering alloys, with low melting point but able to form very stable intermetallic phases (IPs) has motivated various theoretical and experimental research interest on the Cu-In-Sn system. In particular, there is a considerable interest in providing new information on the phase stability properties of the stable IPs as well as those  metastable or hypothetical compounds involved in thermodynamic,so-called CALPHAD sublattice modeling of  the Cu-In-Sn system. The purpose of this work is to use ab-initio methods to study the energetic of some relevant IPs of the Cu-In and Cu-Sn binary subsystems. Specifically we report the energies of formation of the stable compounds e-Cu3Sn (oP8), x-Cu10Sn3 (hP26) and h´-Cu6Sn5 (mC44) of the Cu-Sn system, and d-Cu7In3 (aP40), h-Cu2In (hP6) and CuIn2 (tI12) of the Cu-In system. In addition, considering sublattice models of the type (Cu)a(In,Sn)b we studied ab-initio the corresponding “end-member” compounds generated by adding In to the Cu-Sn phases, and Sn to those of the Cu-In system. Our calculation technique uses the projector augmented wave potentials and the generalized gradient approximation of the exchange and correlation energy. For the stable IPs of the Cu-In and Cu-Sn subsystems, we analyze trends in their stability. We also compare the calculated energies of formation with results previously obtained in a phenomenological CALPHAD-type analysis of the Cu-In-Sn system.