M. A. Wadud et al.
implication of this would be to expect some contribution to hardening from solid solution [13] [22]. Bi rich
platelets are observed in SEM microstructure of Sn-6Zn-3Bi alloy (Figure 2(d)).The continuous decrease of
conductivity can be attributed to solid solution of high resistance Bi phase in solder matrix, which acts as scat-
tering ce nters for cond uction ele ctrons in crystals [26]. Similar criteria were reported by other author [27].
4. Conclusion
Eutectic Sn-Zn alloy and t hr e e Sn -Zn-Bi ternary alloys were cast. Melting behavior, thermal expansion and con-
traction and electrical conductivity were investigated. Thermal properties of Sn-Zn alloy changes with Bi addi-
tion. Melting po int decreases with Bi a ddition. Coefficie nt of thermal expansion a nd coefficient of thermal co n-
traction increase with Bi add ition. Electrical conductivity decreases with Bi add ition.
Acknowledgements
The autho r s ar e gr a teful to B anglad e s h Co unc il of Sc ienti fic and I nd ustr ia l Re sea r ch fo r p ro vid in g t he m wit h the
research facilities to carry out the work.
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