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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Microstructure characterization and tensile properties of directionally solidified Sn-52 wt% Bi-1wt% Sb and Sn-52wt% Bi-2wt% Sb alloys

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Author(s):
Paixao, Jeverton Laureano [1] ; Gomes, Leonardo Fernandes [2] ; Reyes, Rodrigo Valenzuela [2] ; Garcia, Amauri [3] ; Spinelli, Jose Eduardo [4] ; Silva, Bismarck Luiz [1]
Total Authors: 6
Affiliation:
[1] Fed Univ Rio Grande Norte UFRN, Dept Mat Engn, BR-59078970 Natal, RN - Brazil
[2] Univ Fed Sao Carlos, Grad Program Mat Sci & Engn, BR-13565905 Sao Carlos, SP - Brazil
[3] Univ Campinas UNICAMP, Dept Mfg & Mat Engn, BR-13083860 Campinas, SP - Brazil
[4] Fed Univ Sao Carlos UFSCar, Dept Mat Engn, BR-13565905 Sao Carlos, SP - Brazil
Total Affiliations: 4
Document type: Journal article
Source: MATERIALS CHARACTERIZATION; v. 166, AUG 2020.
Web of Science Citations: 0
Abstract

Sn-Bi-based Thermal Interface Materials (TIM) are adequate alloys to promote heat dissipation in power electronics. However, despite the necessary thermal connection, mechanical support for different components and substrates are of prime importance in microelectronic devices. In this framework, the effects of Antimony (Sb) additions on the microstructure and tensile properties of the Sn-52 wt% Bi alloy are investigated. Various Sn-Bi (-Sb) samples solidified at different cooling rates and two levels of Sb-containing alloys allow a comprehensive examination of length scales of either dendritic or eutectic microstructures. A number of experimental techniques are used here to permit a sound analyses of the ternary Sn-Bi(-Sb) alloys: transient directional solidification, optical microscopy (OM), triangle and intercept quantification methods, scanning electron microscopy (SEM), x-ray fluorescence (XRF), x-ray diffraction (XRD), tensile tests and fractography. The addition of Sb enhances the nucleation of primary dendritic trunks, which resulted in a decrease in the primary dendritic arm spacing (lambda(1)) by about 5 times for the Sn-52 wt% Bi-2 wt% Sb alloy as compared to the results for the binary Sn-Bi alloy. The relationships found for tensile properties as a function of the secondary dendritic arm spacing (lambda(2)) demonstrate that Sb additions increase the alloy strength while preserving the ductility. This is due to very thin SnSb intermetallic particles formed in the Sn-rich dendritic matrix. The influence of lambda(2) variation on both the yield and ultimate strengths is roughly insignificant while the ductility varies strongly between 14.4% and 52% for samples solidified from 0.05 degrees C/s to 5.0 degrees C/s respectively. When 2.0 wt% Sb is added, there is a maintenance in the levels of ductility as those found for the binary Sn-Bi alloy. This occurs especially for very refined dendritic and eutectic microstructures samples, which also exhibit a ductile fracture mode. (AU)

FAPESP's process: 17/12741-6 - Application of experimental solidification techniques, characterization of microstructure and properties in the evaluation of eutectic and hypereutectic Al-base and Zn-base alloys
Grantee:José Eduardo Spinelli
Support Opportunities: Regular Research Grants