Microstructural Aspects of Fatigue Parameters of Lead-Free Sn-Zn Solders with Various Zn Content

Open access


The study includes the results of research conducted on selected lead-free binary solder alloys designed for operation at high temperatures. The results of qualitative and quantitative metallographic examinations of SnZn alloys with various Zn content are presented. The quantitative microstructure analysis was carried out using a combinatorial method based on phase quanta theory, per which any microstructure can be treated as an array of elements disposed in the matrix material. Fatigue tests were also performed using the capabilities of a modified version of the LCF method hereinafter referred to in short as MLCF, which is particularly useful in the estimation of mechanical parameters when there are difficulties in obtaining many samples normally required for the LCF test. The fatigue life of alloys was analyzed in the context of their microstructure. It has been shown that the mechanical properties are improved with the Zn content increasing in the alloy. However, the best properties were obtained in the alloy with a chemical composition close to the eutectic system, when the Zn-rich precipitates showed the most preferred morphological characteristics. At higher content of Zn, a strong structural notch was formed in the alloy because of the formation in the microstructure of a large amount of the needle-like Zn-rich precipitates deteriorating the mechanical characteristics. Thus, the results obtained during previous own studies, which in the field of mechanical testing were based on static tensile test only, have been confirmed. It is interesting to note that during fatigue testing, both significant strengthening and weakening of the examined material can be expected. The results of fatigue tests performed on SnZn alloys have proved that in this case the material was softened.

[1] Schmetterer, C., Ipser, H., Pearce, J. (2008). Lead-Free Solders: Handbook of Properties of SAC Solders and Joints, ELFNET COST 531+Lead-Free solders vol. 2, ISBN: 978-80-86292-27-4.

[2] Sobczak, N, Pietrzak, K., Kudyba, A., Nowak, R., Sobczak, J., Wojciechowski, A. (2009). Atlas of microstructures of solder alloys and solder/metal interfaces. Part 1: Optical Microscopy. Motor Transport Institute. ISBN 978-83-60965-04-07. 2009.

[3] Klasik, A., Sobczak, N., Pietrzak, K., Makowska, K., Wojciechowski, A., Kudyba, A, Sienicki, E. (2012). Relationship Between Mechanical Properties of Lead-Free Solders and Their Heat Treatment Parameters. Journal of Materials Engineering and Performance. 21(5), 620-628.

[4] Pietrzak, K., Grobelny, M., Makowska, N. Sobczak, N., Rudnik, D., Wojciechowski, A., Sienicki, E. Structural Aspects of the Behavior of Lead-Free Solder in the Corrosive Solution. Journal of Materials Engineering and Performance. 21, 648-654.

[5] Kroupa, A. (2012). Handbook of High-Temperature Lead- Free Solders. Volume 3: Group Project Reports. COST MP0602, ISBN: 978-80-905363-3-3.

[6] Siewert, T., Liu, S., Smith, D.R., Madeni, J. C. (2002). Database for Solder Properties with Emphasis on New Lead-free Solders NIST, Colorado, February 11.

[7] Kęsy, B.K. (1990). Microstructure as arrangement of unitary phase parts and stereological parameters Proceedings of 3rd Int. Conference on Stereology In Materials Science, Szczyrk, pp. 226 -231.

[8] Pietrzak, K., Klasik, A., Kowalewski, Z. & Rudnik, D. Quantitative relationships between microstructural and mechanical parameters of steels with different carbon content. International Journal of Modern Physics B. 22 (31n32), 5819-5824.

[9] Maj, M. (2012). Fatigue selected alloys. Katowice-Gliwice: Wyd. Archives of Foundry Engineering. (in Polish).

[10] Maj, M. & Piekło, J. (2009). MLCF - an optimised program of low - cycle fatigue test to determine mechanical properties of cast materials. Archives of Metallurgy and Materials. 54(2), 393-397.

[11] Maj, M., Klasik, A., Pietrzak, K., Rudnik D. (2015). Modified low-cycle fatigue (LCF) test. Metalurgija = Metallurgy 54(1), 207-210, ISSN 0543-5846.

[12] Mroziński, S. & Szala, J. (2011). Problem of cyclic hardening or softening in metals under programmed loading. Acta Mechanica et Automatica. 5(3), 99-106.

Archives of Foundry Engineering

The Journal of Polish Academy of Sciences

Journal Information

CiteScore 2016: 0.42

SCImago Journal Rank (SJR) 2016: 0.192
Source Normalized Impact per Paper (SNIP) 2016: 0.316


All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 102 96 5
PDF Downloads 39 38 2