CORRELAÇÃO ENTRE MICROESTRUTURA, RESISTÊNCIAS MECÂNICA E À CORROSÃO DA LIGA DE SOLDAGEM LIVRE DE CHUMBO Sn-0,7%Cu*
CORRELATION BETWEEN MICROSTRUCTURE AND MECHANICAL AND CORROSION RESISTANCES OF A LEAD-FREE Sn-0,7%Cu SOLDER ALLOY
Spinelli, J. E.; Cheung, Noé; Osório, Wislei Riuper Ramos; Freitas, Emmanuelle Sá; Garcia, Amauri
http://dx.doi.org/10.4322/tmm.2014.045
Tecnol. Metal. Mater. Min., vol.11, n4, p.277-286, 2014
Resumo
Ligas do sistema Sn-Cu consistem alternativa promissora na substituição das ligas de soldagem contendo chumbo. Entretanto, pouco se conhece dos efeitos da taxa de resfriamento sobre a microestrutura de solidificação dessas ligas, bem como das alterações provocadas nas resistências mecânicas e à corrosão. No presente trabalho, a técnica de solidificação unidirecional transitória foi empregada para obtenção de um lingote de Sn-0,7%Cu (em peso). Os resultados experimentais incluem: parâmetros térmicos de solidificação (taxa de resfriamento, Ṫ, velocidade de solidificação, v, e coeficiente de transferência de calor metal/substrato, hi), espaçamentos celular, λc, e dendrítico primário, λ1, taxa de corrosão, potencial de corrosão e resistência à polarização, além de resistência mecânica e ductilidade. Os resultados mostram uma transição microestrutural do tipo celular/dendritica com prevalência de células eutéticas para Ṫ< 0,9°C/s. Menores niveis de resistência à corrosão foram associados às regiões de morfologia dendrítica em comparação com regiões de células eutéticas. Nas regiões dendríticas foi observada a presença de intermetálico Cu6Sn5 extremamente fino e de morfologia fibrosa.
Palavras-chave
Liga Sn-Cu, Solidificação, Propriedades mecânicas, Corrosão
Abstract
Sn-Cu alloys are promising alternatives to the replacement of Pb-containing solder alloys. However, the effects of the cooling rate on the solidification microstructures of these alloys and the corresponding influence on the mechanical and corrosion resistances are not well known. In the present study, the transient directional solidification technique has been used to obtain a Sn-0,7wt.%Cu ingot. The experimental results include: solidification thermal parameters (cooling rate, Ṫ, growth rate, v, and metal/substrate heat transfer coefficient, hi), cellular spacing, λc, and primary dendritic arm spacing, λ1, corrosion rate, corrosion potential and polarization resistance and mechanical strength and ductility. The results show a cellular/dendritic transition with eutectic cells prevailing for Ṫ< 0,9°C/s. Lower corrosion resistances have been associated with dendritic regions compared with regions characterized by eutectic cells. In the interdendritic regions extremely fine and fibrous Cu6Sn5 intermetallic particles can be observed.
Keywords
Sn-Cu alloy, Solidification, Mechanical properties, Corrosion
Referências
1 Wu CML, Yu DQ, Law CMT, Wang L. The properties os Sn-9Zn lead-free solder alloys doped with trace rare earth
elements. Journal of Electronic Materials. 2002;31(9):921-927. http://dx.doi.org/10.1007/s11664-002-0184-6.
2 Pareck N. NASA Parts and Packaging Program, Lead-free solders, Goddard Space Flight Center. Maryland: Greenbelt;
1996.
3 Çadirli E, Böyük U, Engin S, Kaya H, Marasli N, Keslioglu K, et al. Investigation of the effect of solidification
processing parameters on the rod spacings and variation of microhardness with the rod spacing in the Sn–Cu
hypereutectic alloy. Journal of Materials Science. 2010;21:608-618.
4 Nogita K, Read J, Nishimura T, Sweatman K, Suenaga S, Dahle A. Microstructure control in Sn-0.7mass%Cu alloy.
Materials Transactions. 2005;46(11):2419-2425. http://dx.doi.org/10.2320/matertrans.46.2419.
5 Bouchard D, Kirkaldy JS. Prediction of dendrite arm spacings in unsteady-and steady-state heat flow of
unidirectionally solidified binary alloys. Metallurgical and Materials Transactions. B, Process Metallurgy and Materials
Processing Science. 1997;28(4):651-663. http://dx.doi.org/10.1007/s11663-997-0039-x.
6 Hunt JD, Lu SZ. Numerical modeling of cellular/dendritic array growth: spacing and structure predictions.
Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science. 1996;27(3):611-623. http://
dx.doi.org/10.1007/BF02648950.
7 Somboonsuk K, Trivedi R. The first sidebranch instability of dendritic structures. Scripta Metallurgica.
1984;18(11):1283-1286. http://dx.doi.org/10.1016/0036-9748(84)90123-6.
8 Çadirli E, Böyük U, Engin S, Kaya H, Marasli N, Ülgen A. Experimental investigation of the effect of solidification
processing parameters on the rod spacing in the Sn-1.2wt.%Cu alloy. Journal of Alloys and Compounds.
2009;486(1-2):199-206. http://dx.doi.org/10.1016/j.jallcom.2009.07.027.
9 Liang J, Dariavach N, Shangguan D. Solidification condition effects on microstructures and creep resistance of
Sn-3.8Ag-0.7Cu lead-free solder. Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials
Science. 2007;38(7):1530-1538. http://dx.doi.org/10.1007/s11661-007-9222-6.
10 Chemingui M, Khitouni M, Jozwiak K, Mesmacque G, Kolsi A. Characterization of the mechanical properties
changes in an Al–Zn–Mg alloy after a two-step ageing treatment at 70 and 135°C. Materials & Design.
2010;31(6):3114-3139. http://dx.doi.org/10.1016/j.matdes.2009.12.033.
11 Wang L, Zhang BP, Shinohara T. Corrosion behavior of AZ91 magnesium alloy in dilute NaCl solutions. Materials &
Design. 2010;31(2):857-863. http://dx.doi.org/10.1016/j.matdes.2009.07.049.
12 Kocatepe K. Effect of low frequency vibration on porosity of LM25 and LM6 alloys. Materials & Design.
2007;28(6):1767-1775. http://dx.doi.org/10.1016/j.matdes.2006.05.004.
13 Kucukomeroglu T. Effect of equal-channel angular extrusion on mechanical and wear properties of eutectic Al–12Si
alloy. Materials & Design. 2010;31(2):782-789. http://dx.doi.org/10.1016/j.matdes.2009.08.004.
14 Osório WR, Peixoto LC, Garcia A. Comparison of electrochemical performance of as-cast Pb 1wt.%Sn and Pb
1wt.% Sb alloys for lead-acid battery components. Journal of Power Sources. 2010;195(6):1726-1730. http://dx.doi.
org/10.1016/j.jpowsour.2009.09.054.
15 Li D, Conway PP, Liu C. Corrosion characterization of tin–lead and lead free solders in 3.5 wt.% NaCl solution.
Corrosion Science. 2008;50(4):995-1004. http://dx.doi.org/10.1016/j.corsci.2007.11.025.
16 Frear DR, Jones WB. Solder mechanics, a state of the art assessment. Pennsylvania: The Minerals, Metals & Materials
Society; 1991.
17 Kariya Y, Hirata Y, Otsuka M. Effect of thermal cycles on the mechanical strength of quad flat pack leads/Sn-3.5Ag-X
(X=Bi and Cu). Journal of Electronic Materials. 1999;28(11):1263-1269. http://dx.doi.org/10.1007/s11664-999-
0166-z.
18 Siqueira C, Cheung N, Garcia A. Solidification thermal parameters affecting the columnar to equiaxed transition.
Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science. 2002;33(7):2107-2118. http://
dx.doi.org/10.1007/s11661-002-0042-4.
19 Gunduz M, Çardili E. Directional solidification of aluminium-copper alloys. Materials Science and Engineering A.
2002;327(2):167-185. http://dx.doi.org/10.1016/S0921-5093(01)01649-5.
20 Stern M, Geary AL. Electrochemical Polarization 1. A Theoretical Analysis of the Shape of Polarization Curves.
Journal of the Electrochemical Society. 1957;104(1):56-63. http://dx.doi.org/10.1149/1.2428496.
21 Cheung N, Santos NS, Quaresma JMV, Dulikravich GS, Garcia A. Interfacial heat transfer coefficients and
solidification of an aluminum alloy in a rotary continuous caster. International Journal of Heat and Mass Transfer.
2009;52(1-2):451-459. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2008.07.003.
22 Santos CA, Quaresma JMV, Garcia A. Determination of transient interfacial heat transfer coefficients in chill
mold castings. Journal of Alloys and Compounds. 2001;319(1-2):174-186. http://dx.doi.org/10.1016/S0925-
8388(01)00904-5.
23 Tewari N, Raj SV, Locci IE. A Comparison between growth morphology of “eutectic” cells/dendrites and singlephase
cells/dendrites. Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science.
2004;35(5):1632-1635. http://dx.doi.org/10.1007/s11661-004-0269-3.
24 Rosa DM, Spinelli JE, Ferreira IL, Garcia A. Cellular/dendritic transition and microstructure evolution during
transient directional solidification of Pb-Sb alloys. Metallurgical and Materials Transactions. A, Physical Metallurgy and
Materials Science. 2008;39(9):2161-2174. http://dx.doi.org/10.1007/s11661-008-9542-1.
25 Rocha OL, Siqueira CA, Garcia A. Cellular/dendritic transition during unsteady state unidirectional solidification
of Sn-Pb alloys. Materials Science and Engineering A. 2003;347(1-2):59-69. http://dx.doi.org/10.1016/S0921-
5093(02)00581-6.
26 Zhong XK, Zhang G, Qiu Y, Chen ZY, Guo XP, Fu CY. The corrosion of tin under thin electrolyte layers containing
chloride. Corrosion Science. 2013;66:14-25. http://dx.doi.org/10.1016/j.corsci.2012.08.040.
27 Aziz-Kerrzo M, Conroy KG, Fenelon AM, Farrell ST, Breslin CB. Electrochemical studies on the stability and
corrosion resistance of titanium-based implant materials. Biomaterials. 2001;22(12):1531-1539. http://dx.doi.
org/10.1016/S0142-9612(00)00309-4. PMid:11374452
28 Osório WR, Spinelli JE, Afonso CRM, Peixoto LC, Garcia A. Microstructure, corrosion behaviour and microhardness
of a directionally solidified Sn Cu solder alloy. Electrochimica Acta. 2011;56(24):8891-8899. http://dx.doi.
org/10.1016/j.electacta.2011.07.114.
Facebook
Google+
Twitter
LinkedIn
Mendeley
StumbleUpon
CiteULike
Reddit
Email