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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.)

The use of a directional solidification technique to investigate the interrelationship of thermal parameters, microstructure and microhardness of Bi-Ag solder alloys

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Spinelli, Jose Eduardo [1] ; Silva, Bismarck Luiz [1] ; Cheung, Noe [2] ; Garcia, Amauri [2]
Total Authors: 4
[1] Univ Fed Sao Carlos, Dept Mat Engn, BR-13565905 Sao Carlos, SP - Brazil
[2] Univ Estadual Campinas, Dept Mfg & Mat Engn, BR-13083970 Campinas, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: MATERIALS CHARACTERIZATION; v. 96, p. 115-125, OCT 2014.
Web of Science Citations: 7

Bi-Ag alloys have been stressed as possible alternatives to replace Pb-based solder alloys. Although acceptable melting temperatures and suitable mechanical properties may characterize such alloys, as referenced in literature, there is a lack of comprehension regarding their microstructures (morphologies and sizes of the phases) considering a composition range from 1.5 to 4.0 wt.%Ag. In order to better comprehend such aspects and their correlations with solidification thermal parameters (growth rate, v and cooling rate, T), directional solidification experiments were carried out under transient heat flow conditions. The effects of Ag content on both cooling rate and growth rate during solidification are examined. Microstructure parameters such as eutectic/dendritic spacing, interphase spacing and diameter of the Ag-rich phase were determined by optical microscopy and scanning electron microscopy. The competition between eutectic cells and dendrites in the range from 15 to 4.0 wt.%Ag is explained by the coupled zone concept. Microhardness was determined for different microstructures and alloy Ag contents with a view to permitting correlations with microstructure parameters to be established. Hardness is shown to be directly affected by both solute macrosegregation and morphologies of the phases forming the Bi-Ag alloys, with higher hardness being associated with the cellular morphology of the Bi-2.5 and 4.0 wt.%Ag alloys. (C) 2014 Elsevier Inc. All rights reserved. (AU)

FAPESP's process: 13/08259-3 - Microstructure and mechanical behavior of Sn-Bi-Cu and Sn-Bi-Ag lead-free solder alloys
Grantee:Bismarck Luiz Silva
Support type: Scholarships in Brazil - Doctorate
FAPESP's process: 13/13030-5 - Microstructure, thermal parameters, segregation and mechanical properties of lead-free Sn-based, Zn-based and Bi-based solder alloys
Grantee:José Eduardo Spinelli
Support type: Regular Research Grants