Bi-Sn-Zn & Pd-Sn-Zn Systems:Summary of the Results

Jiri Vizdal1 and Ales Kroupa2

Ph

ase

Eq

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ria

in L

ead

-fre

e

sold

ers2Structure of Phases Group

Department of Structure Institute of Physics of Materials, AS CR

Brno, Czech Republic

1Department of Inorganic Chemistry / Materials

ChemistryFaculty of ChemistryUniversity of ViennaVienna, Austria

Pb

Presentation outline

Aims + used methodology

Experimental methods summary

Results…• Bi-Sn, Bi-Zn, Bi-Sn-Zn• Pd-Zn, Pd-Sn-Zn

Conclusions

Our goals and how to achieve them...

Aims & methodology

Our work was aimed at thermodynamic and experimental description of phase equilibria in the Bi-Sn-Zn, Pd-Sn-Zn (Pd – Pd/Ni substrate coatings) systems and relevant subsystems >>>

• contribution to new Pb-free solders design

Analysis + literature survey:• optimal thermodynamic assessments selection (if exist!)• 1. version of the thermodynamic database

Theoretical study („CALPHAD“ -> Thermo-Calc):• predictions calculations

Experimental study (SEM + EDS/WDS, DTA/DSC, etc.)

Theoretical study:• modelling -> „COST531“ thermodynamic database

expansion

Exp. methods summary

Experimental details

Materials, treatment Bi, Sn, Zn, Pd ≥ 99,95 %

Samples were sealed under vacuum into quartz capsules.

Homogeneity {SEM (BSE) + EDS}.

Heat treatment – annealing (different T, t).

Coolant: H2O.

Phase identification and composition measurement. >>>

Phase transformations temperatures measurement. >>>

Exp. methods SEM + EDS/WDS (JEOL JSM-

6460; BSE; 20 keV / INCA + standards + ZAF)

TEM + EDS (TEM/STEM Philips CM 12 / EDAX Phoenix CM 12)

DTA/DSC (Netzsch DTA/DSC 404; Dept. of Inorganic Chemistry / Materials Chemistry, University of Vienna):

• standards: Au/Ag• vheating/cooling ~ 2 °C/min.• accuracy: ±2 °C• atmosphere: vacuum/Ar

Experimental & TheoreticalResults

Bi-Sn: Final assessment

Bi-Sn: optimization results

Enthalpy of mixingin comparison to

experimental datafrom [ASR 2004] and

[SHARKEY 1972]

Calculated activityof Sn in Liq. in

comparison to exp.data from Asryan &Mikula [ASR 2004]

Newly modified Bi-Sn system description,that was originally published by [OHT 1994]

TE ~ 138.4 °C

[COST 2006]

Bi-Zn: Final assessment

Bi-Zn: assessment correction

SEM/WDS

Overall compos.Bi-76.2Zn

Bi in HCP_Zn (Zn)0.3 0.2

Zn in (Bi)0.3 0.1

Values in wt. %

Annealed 864 h/200 °C

Liq.

Liq. + (Zn)

(Bi) + (Zn)

Malakhov [MAL 2000] After change

Malakhov [MAL 2000]: 35 000 J/molOptimization: 25 000 J/mol

)Zn(Va:Zn,BiL0

Bi-Sn-Zn: New assessment

Bi-Sn-Zn: selected isopleths

Isothermal section (120 °C)together with selected

vertical sectionscompared to availableexperimental data…

BC

D

E

A

(Bi)

+ (Sn)

+ (Zn)

T = 120 °C

(Bi) + (Sn) + (Zn)

Liq. + (Bi)+ (Zn)

Liq. + (Sn)+ (Zn)

x(Zn) = 5 at. %

Liq. + (Sn) + (Zn)

Liq. + (Zn)

(Bi) + (Sn) + (Zn)

w(Sn) = 59 hm. %

(Sn) + (Zn)

(Bi) + (Sn) + (Zn)

Liq. + (Zn)

(Bi) + (Zn)

w(Zn) = 12 hm. %

Liq. + (Zn)

T1 + + T2

(Bi) + (Sn) + (Zn)

(Sn) +

(Zn)

A B

Bi/Zn = 1/2

[Th

is

work

]

[BR

A

2007]

[BR

A

2007]

[LU

EF

2006]

At.%

[COST 2006]

Bi-Sn-Zn: New assessment

Bi-Sn-Zn: therm. properties

Activities in comparison toexp. data from [OLE 1959]

Enthalpies of mixingcompared to exp.

data from [LUEF 2006]

43

21

[COST 2006]

Pd-Zn: The reason of study

Pd-Zn: overview

Massalski’s experimental phase diagram [MASS 1990]

Phase diagram by Hansen and Anderko [HAN 1958]

• Thermodynamic activities of Zn in ordered β1 Pd-Zn alloys at 1000 °C weremeasured by Kou and Chang [KOU 1975].

• Partial molar and integral properties were determined from vapour pressuremeasurements by Chiang [CHI 1977] (477 – 1030 °C / 0 – 83 at. % Zn).

? ?

[E-MRS 2005]

Pd-Zn: New assessment

Pd-Zn: phase diagram

The detail of the phase diagram showingnew exp. information – marked invariantreactions (DTA) and phase‘s composition(SEM + EDS).

Pd-Zn phase diagram, calculated on the basis ofnewly optimized thermodynamic parametersin comparison with available exp. data.

[E-MRS 2005]

Pd-Zn: New assessment

Pd-Zn: therm. properties

Comparison of exp. measured [CHI 1977] and calculated values of:

1. Zn activities in (Pd);2. integral molar Gibbs energy for the Pd-Zn system

at 1000 °C in different concentration ranges.

[E-MRS 2005]

Binary prediction + proposed exp. alloys

Pd-Sn-Zn: prediction + exp.

Calculated isothermal sections in the Pd-Sn-Zn system at 500 and 900 °Cbased only on binary data together with marked exp. alloys.

500 °C 900 °C

Experimental phase diagram

Pd-Sn-Zn: SEM/TEM + EDS

Preliminary experimental phase diagrams design – isothermal sections constructedaccording to SEM/TEM + EDS marked experimental results.

500 °C 900 °C

Conclusions

Conclusions…

Bi-Sn-Zn system and relevant subsystems:• Exp. determined max. solubility of Bi in (Sn) at TE ~ 10 wt. % -> created new

assessment of the Bi-Sn system.

• Exp. determined solubilities of Bi in (Zn) and Zn in (Bi) at T = 200 °C -> correction of the present Bi-Zn assessment.

• Exp. study of the Bi-Sn-Zn system (SEM + EDS/WDS, DTA) -> own results + results from literature were used for the new assessment (interact. param. for Liq. and (Bi)).

Pd-Zn and Pd-Sn-Zn systems:• Exp. study of Zn-rich part of the Pd-Zn phase diagram verified presence of the η-

phase at T = 400 °C.

• Eutectic reaction was established in this part of the Pd-Zn diagram: Liq. η + (Zn).

• First thermodynamic description of the Pd-Zn system has been created.

• First predictions within the Pd-Sn-Zn system were calculated and relevant exp. results at 500 a 900 °C were obtained. These were used for the preliminary exp. phase diagram construction.

Presented finished thermodyn. descriptions of the Bi-Sn, Bi-Zn, Pd-Zn and Bi-Sn-Zn systems are in very good agreement with available data and sets of thermodynamic parameters were included in the „COST531“ database.

Acknowledgements

This work was supported by following projects:• COST No. OC 531.002 (Ministry of Education of the Czech Republic)

• No. 106/05/H008 (Czech Science Foundation)

• AV0Z20410507 (Research project)

Cooperation:• Dr. Milan Svoboda (IPM AS CR)• Prof. Klaus W. Richter (University of Vienna)• Dr. Christoph Luef (University of Vienna)• Prof. Aloke Paul (Indian Institute of Science)• Prof. M. H. Braga (Universidade do Porto)• Prof. L. F. Malheiros (Universidade do Porto)• Prof. D. Soares (Universidade do Minho)

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Literature

[COST 2006] Vizdal, J., Braga, M.H., Kroupa, A., Malheiros, L.F., Soares, D.:In COST 531 Mid-Term Meeting, Genoa, Italy, 2006.

[ASR 2004] Asryan, N., Mikula, A.: Z. Metallkd. 95 (2004).

[SHARKEY 1972] Sharkey, R.L., Pool, M.J.: Met. Trans. 3 (1972).

[OHT 1994] Ohtani, H., Ishida, K.: J. of El. Mat. 23 (1994).

[OEL 1958] Oelsen, W., Golücke, K.F.: Arch. Eisenhüttenw. 29 (1958).

[NAG 1952] Nagasaki, S., Fujita, E.: J. Jpn. Inst. Met. 16 (1952).

[MAL 2000] Malakhov, D.V.: Calphad 24 (2000).

[BRA 2007] Braga, M.H., Vizdal, J., Kroupa, A., Ferreira, J., Soares, D., Malheiros, L.F.:

Calphad, accepted for publication, 2007.

[LUEF 2006] Luef, Ch., Paul, A., Vizdal, J., Kroupa, A., Kodentsov, A., Ipser, H.:Monatsh. Chem. 137 (2006).

[OLE 1959] Oleari, L., Fiorani, M.: L. Ricerca Scientifica 29 (1959).

[E-MRS 2005] Vizdal, J., Kroupa, A., Popovic, J., Zemanova, A.: In E-MRS int. Fall Meeting,

p. 177, ISBN 83-89585-07-3, Warsaw, Poland, 2007.

[MASS 1990] Massalski, T.B.: Binary Alloy Phase Diagrams, ASM Int., Ohio, USA 1990.

[HAN 1958] Hansen, M., Anderko, K.: Constitution of Binary Alloys, New York, 1958.

[KOU 1975] Kou, S., Chang, Y.A.: Acta Metall. 23 (1975).

[CHI 1977] Chiang, T., et al.: Z. Metallkd. 68 (1977).