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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, phases morphologies and hardness of a Bi-Ag eutectic alloy for high temperature soldering applications

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Spinelli, Jose Eduardo [1] ; Silva, Bismarck Luiz [1] ; Garcia, Amauri [2]
Total Authors: 3
[1] Univ Fed Sao Carlos, Dept Mat Engn, UFSCar, BR-13565905 Sao Carlos, SP - Brazil
[2] Univ Estadual Campinas, UNICAMP, Dept Mat Engn, BR-13083970 Campinas, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: MATERIALS & DESIGN; v. 58, p. 482-490, JUN 2014.
Web of Science Citations: 23

The conversion to RoHS-compliant lead-free assembly has been a considerable challenge to the electronics industry. Among several alternative solder alloys, Bi-Ag alloys have been highlighted as a potential candidate to replace high Pb solder alloys for applications in oil and gas, automotive and avionics industries. The typical melting temperatures of Bi-Ag near-eutectic alloys are considered acceptable and excellent mechanical properties may be achieved with appropriate microstructures. Such promising alloys for high temperature soldering remain barely understood especially regarding non-equilibrium solidification features. In this study, a directional solidification experiment was carried out with the Bi-2.5 wt%Ag eutectic so that a large range of cooling rates (T) over dot could be obtained under unsteady-state conditions. The experimental investigation include: thermal solidification parameters (growth rate, v and cooling rate, (T) over dot), microstructure parameters (eutectic/dendritic spacing, interphase spacings) and phases morphologies analyzed by optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and hardness. Experimental interrelations between hardness and microstructure (scale and morphology) of the eutectic Bi-Ag are reported. Solidification parameters are also associated with each configuration observed along the casting, i.e., coexistence of dendrites and eutectic cells for regions very close to the cooled casting surface, eutectic cells prevailing and eutectic cells together with beta-Bi primary phase. The cell spacing, lambda(c), is correlated with hardness by Hall-Petch type equations. (C) 2014 Elsevier Ltd. All rights reserved. (AU)

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