H. Kaya 1 , S. Engin 2 , E.Çadırlı 3 , U. Böyük 1 , N. Maraşlı 2

1. Figure3. (a) Variation of the microhardness with the eutetic spacings. (b) Variation of the Ultimate tensile strength with the eutetic spacings. Rate=10 K/min Area =332.597 mJ Onset= 411.36 K End= 416,63 K DH= 46.60 J/g Peak=414,78 K Temperature (K) Figure4. (a) Variation of the electrical resistivity with the eutetic spacings. (b) Variation of the Ultimate tensile strength with the eutetic spacings. b a Investigation of Physical Parameters of the Bi-Sn-Ag Eutectic Alloy H. Kaya1, S. Engin2, E.Çadırlı3, U. Böyük1, N. Maraşlı2 1Erciyes University, Department of Science Education, Kayseri, Turkey, 2 Erciyes University, Department of Physics, Kayseri, Turkey , 2Erciyes University, Department of Physics, Niğde, Turkey, 1. Introduction Unidirectional solidification of eutectic alloys has received considerable attention in the past few years because the alignment of fibers or plates in some of these eutectics produces attractive directional physical or mechanical properties. Most of the work has been done on binary alloys of eutectic and near eutectic compositions, and only recently work has been initiated in the area of ternary eutectic alloys. The development of lead-free solders has emerged as one of the key issues in the electronics packaging industries. Bi-Sn-Ag ternary alloy has been considered as one of the lead-free solder materials that can toxic Pb-Sn eutectic solder without increasing soldering soldering temperature. This study investigates the effect of temperature gradient and growth rate on the mechanical properties of the Bi-43.47 wt.% Sn-0.68 wt.% Ag alloy. 3.Experimental Results 2. Experimental Procedure 2.1 Solidification and microstructures Bi-Sn-Ag alloy was directionally solidified upward with different solidification condition (V=6.6-132.8 mm/s, G=constant, and also, G=2.3-5.7 K/mm, V= constant) using a Bridgman–type growth apparatus (Fig. 1). The quenched samples were removed from the graphite crucible and the metallographic process, the microstructures of the samples were revealed (Fig. 2). 2.2. Measurement of Mechanicalproperties Microhardness values of the samples were measured with a FutureTech FM700 model hardness test device using a 500 g load and a dwell time of 10 s. Variations of HV with the eutectic spacings are plotted and shown in Fig. 3a.The ultimate tensile strength (UTS) values were measured at room temperature at a strain rate of 103 s1 by Shimadzu AG-IS universal testing machine. The round rod tensile samples with a diameter of 4 mm and a gauge length of 20 mm were prepared from directionally solidified rod samples with different eutectic spacings. Typical strength-strain curves of the Bi-Sn-Ag alloy are shown in Figs. 3b. 2.3. Measurement of Electrical properties The electrical resistivity strongly depends on solidification condition. In eutectic alloys, electrical resistivity decreases with increasing eutectic spacings. The dependence of the electrical resistivity on eutectic spacings were also analyzed in this work. Variations of r with the microstructure parameter are plotted and shown in Figs. 4. The enthalpy of fusion (DH) for the Bi-43.47 wt.% Sn-0.68 wt.% Ag eutectic alloy was determined by differential scanning calorimeter (DSC) from heating trace during the transformation from solid to liquid. 4. Conclusions In present work, the influence temperature and solidificationprocessing parameters on themechanical properties of Sn- Bi-Ag ternary alloy were investigated.The results aresummarized as follows: 1.The values of HV have been measured at least 30 regions on the sample. It was found that the values of microhardness decrease with increasing the values of l. The establishment of the relationships among HV, V and G can be given HV=13.5 l-0.27. 2. The stresses values are decrease with increasing the values of l. The establishment of the relationships among σand l can be given as; s=9.7 l-0.59 3. The electrical resistivity values are decrease with increasing the values of l. The establishment of the relationships among rand l can be given as; r=4.77x10-6(l)-0.13. 4.Bi-Sn-Ag eutectic alloy was heated with heating rate of 10 K/min from 300 K to 450 K. From the plot of heat flow versus temperature, the melting temperature, the enthalpy of fusion and the specific heat were found to be 414.78 K, 53.43 J/g, and 0.236 J/g K, respectively. Figure 1. (a) Block diagram of the experimental setup (b) The details of the Bridgman type directional solidification furnace. • References • H. Kaya, M. Gündüz, E.Çadırlı, O.Uzun, J.Mat. Sci. 2004;39, 6571-6576. • Kaya H., Böyük U., Engin S., Çadırlı E., and Maraşlı N., J. Elect. Mater, 2010: 39(3),303-311 • K.W. Richter, H. Ipser, Intermetallics 11 (2003) 101. • M. Gündüz, H. Kaya, E. Çadırlı and A. Özmen, Mat. Sci. Eng. A 369 (2004) 215. • H. Kaya, U. Böyük, E. Çadırlı, N. Maraşlı, Kovove Mater. 48(5) (2010) 291. • Kaya H., Çadırlı E., Gündüz M. and Ülgen A. J. Mat. Eng. and Perf., 12(5),544–551. • H. Kaya, U. Böyük, E. Çadırlı, N. Maraşlı, Materials and Design,in press (2011). • R. Brandt, G. Neuer, Int J Thermophys 28 (2007) 1429–1446. • Khan S, Ourdjini A, Hamed QS, Najafabadi MAA,. Elliott R. J. Mater. Sci. 1993; 28: 5957. Figure 2. Typical optical images of the growth morphologies of directionally solidified Sn-Bi-Ag eutectic alloy on transverse section (a): G=2.33 K/mm, V=13.25 mm/s and (b) G=2.33 K/mm, V=132.83 mm/s.