Thermodynamic Reassessment of the Cu-Ni-Sn System

Adela Zemanova, Ales Kroupa

Institute of Physics of Materials, AS CR, Brno, Czech RepublicInstitute of Physics of Materials, AS CR, Brno, Czech Republic

� Introduction

� Unification of modelsExamples

NiAs, Ni2In types

� Cu-Ni-Sn ternary system

Outline of the talkOutline of the talk

� Cu-Ni-Sn ternary system

- model

- 400, 500 and 700 °C isothermal sections

- enthalpy of mixing

� Conclusions

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Creation of consistent TD

The Gibbs energy descriptions included in the database should be unique, based on the same assumptions, conditions and models.

A reliable thermodynamic database has to be consistent with respect to:

1. models used for the expression of Gibbs energy functions in the

IntroductionIntroduction

1. models used for the expression of Gibbs energy functions in the system

2. models and names used for the description of phases, included in the system

3. thermodynamic data used for the same elements and compounds in different systems, starting with unary data for stable and unstable crystallographic structures for all elements, included in the database.

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IntroductionIntroduction

Selection of sublattice model for the description of a particular phase and allocation of a name to it.

� The same systems were often modelled several times by various authors – identification of models used in these assessments, number of sublattices, sublattice ratios, etc.

� Phases with the same or similar crystallographic structure � NiAs prototype, Pearson symbol hP4

Creation of consistent TD – condition 2

� NiAs prototype, Pearson symbol hP4� Ni2In prototype, Pearson symbol hP6� in the ternary In-Ni-Sb system - complete solubility was found

experimentally between the phases, which are not identical from the crystallographic point of view (they are similar but not the same).

� Cu-Ni-Sn - two phase field between the Cu6Sn5_HT (NiAs prototype) and Ni3Sn2 (Ni2In prototype)

� The theoretical assessments of relevant binary systems were prepared by various authors, various models were used.

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NiAs prototype Pearson symbol hP4

Ni2In prototype Pearson symbol hP6

Examples Examples NiAs, Ni2In types

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Examples Examples NiAs, Ni2In typesIn-Ni-Sb system – complete solubility (K.W. Richter)

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CuCu--NiNi--SnSn Isothermal cross section at 400Isothermal cross section at 400 °°CC

Schmetterer, C., Flandorfer, H., Luef, C., Kodentsov, A., Ipser, H.: Journal of Electronic Mater.,

2009, 38, 10.

Examples Examples NiAs, Ni2In types

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Examples Examples NiAs, Ni2In types

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Examples Examples NiAs, Ni2In types

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Examples Examples NiAs, Ni2In types

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CuCu--NiNi--SnSn SystemSystem• Complete solubility between phases with NiAs and Ni2In prototype structures in In-Ni-Sb system requires one model to describe properly this feature

• Therefore three-sublattice model (Cu,Ni)(Cu,Ni,Va)(Sn) with the sublattice ratio 1:1:1 was selected

• Two phase field exist in Cu-Ni-Sn system between the Cu6Sn5_HT (NiAs prototype) and Ni3Sn2 (Ni2In prototype)

• New assessment is currently in progress to test the possibility to describe these two phases with one model and to obtain proper “miscibility gap” in the Cu-Ni-Sn system

• Binary system Cu-Sn and Ni-Sn had to be reassessed• Ternary system reassessment under construction

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CuCu--NiNi--SnSn SystemSystem

Cu-Sn Binary System Ni-Sn Binary System

(NI2

IN_T

YP

E)

Liu, X.J., Liu, H.S., Ohnuma, I., Kainuma,R., Ishida, K., Itabashi, S., Kameda, K.,Yamaguchi, K.: J. Electron. Mater., 2001,

30, 1093-1103.

The calculated phase diagram modified according to Schmetterer, C. et al.

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(NI2IN_TYPE)

(NI2

IN_T

YP

E)

CuCu--NiNi--Sn Isothermal cross section at 400Sn Isothermal cross section at 400 °°CCThe experimental phase diagramCalculated phase diagram

Ni

τ1τ2

Ni3Sn_LT

Ni3Sn4

Ni3Sn2(NI2IN_TYPE) FCC_A1

Schmetterer, C., Flandorfer, H., Luef, C., Kodentsov, A., Ipser, H.: Journal of Electronic Mater., 2009, 38, 10. 13

τ1 – ternary βCu3Ti-type phaseτ2 – ternary triclinic, distorted

βCu3Ti-type phase

Sn Cu

BCC_A2

Cu6Sn5(NI2IN_TYPE)

Cu10Sn3

CuCu--NiNi--Sn Isothermal cross section at Sn Isothermal cross section at 550000 °°CCThe experimental phase diagramCalculated phase diagram

Ni

FCC_A1

Ni3Sn2(NI2IN_TYPE)

Ni3Sn_LT

τ1

Schmetterer, C., Flandorfer, H., Luef, C., Kodentsov, A., Ipser, H.: Journal of Electronic Mater., 2009, 38, 10.

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CuSn

Ni3Sn4

BCC_A2

LCu10Sn3

CuCu--NiNi--Sn Isothermal cross section at Sn Isothermal cross section at 770000 °°CCThe experimental phase diagramCalculated phase diagram

Ni

Ni3Sn4

Ni3Sn2(NI2IN_TYPE) τ1

Ni3Sn_LT

FCC_A1

Schmetterer, C., Flandorfer, H., Luef, C., Kodentsov, A., Ipser, H.: Journal of Electronic Mater., 2009, 38, 10.

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Sn CuL

BCC_A2

The enthalpy of mixing in liquid The enthalpy of mixing in liquid CuCu--NiNi--Sn alloys at 1580 K Sn alloys at 1580 K

The reference states used are pure liquid components

Cu:Sn=2:1 Cu:Sn=3:2 Cu:Sn=1:1

M.J. Pool, I. Arpshofen, B. Predel and E. Schultheiss: Z. Metallkd., Vol. 70 (1979), p. 656.16

Conclusions IConclusions I

� Unification of sublattice models for crystallographically identical phases or for phases with complete solubility is crucial for complete consistency of any thermodynamic database.� The complexity of the problem was illustrated on NiAs and Ni2In prototype phases, where both two-phase fields and completely solubility exist in different ternary systems� The use of unified models was demonstrated on the Cu-Ni-Sn system system � The Cu-Sn and Ni-Sn binary systems had to be reaassessed using new models, Ni-Sn binary diagram was modified according to Schmetterer, C. et al.� 400, 500 and 700 °C isothermal sections of the Cu-Ni-Sn ternary phase diagram were assessed.

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�Very good agreement was reached for the two phase equilibrium between Cu6Sn5_HT (NiAs prototype) and Ni3Sn2 (Ni2In prototype) phases with respect to the existing experimental data and previous description of this phase.

�This indicates the possibility to generalize the models in the database to cover all possible relation between phases with

Conclusions IIConclusions II

database to cover all possible relation between phases with identical and similar crystallographical structure. .

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AcknowledgementAcknowledgement

The authors are grateful to the Ministry of Education of the Czech Republic (projects No. OC08053),

Calculations were performed by THERMO-CALC andPANDAT software.

Thank you for your attention.

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