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    Dendritic solidification and characterization of a succinonitrile-acetone alloy
    (IOP PUBLISHING LTD, 2006) Ustun, Erkan; Cadirli, Emin; Kaya, Hasan
    A succinonitrile (SCN)-3.6 wt% acetone (ACE) alloy was unidirectionally solidified with a constant temperature gradient G = 5.7 K mm(-1) in the growth rate ranges V = 6.5 - 113 mu m s(-1) and a constant growth rate V = 6.5 mu m s(-1) in the temperature gradient ranges G = 3.5-5.7 K mm(-1). The primary dendrite arm spacings, secondary dendrite arm spacings, dendrite tip radius and mushy zone depth were measured as a function of growth rate and temperature gradient. Theoretical models for the dendrite arm spacing and tip radius have been compared with the experimental observations, and a comparison of our results with the current theoretical models and previous experimental results has also been made. The stability constant (s) for this alloy system was measured and this result was compared with various similar organic transparent alloys.
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    Dependency of structure, mechanical and electrical properties on rotating magnetic field in the Bi-Sn-Ag ternary eutectic alloy
    (CARL HANSER VERLAG, 2016) Kaya, Hasan; Cadirli, Emin; Gunduz, Mehmet; Raebiger, Dirk; Eckert, Sven
    In the present study, cylindrical samples of the Bi-Sn-Ag ternary eutectic alloy were exposed to a rotating magnetic field (RMF) during upward solidification. The dependence of the eutectic spacing (lambda), microhardness (HV), tensile stress (sigma) and electrical resistivity (rho) of the Bi-Sn-Ag eutectic alloy on the RMF-driven flow was investigated in this study. With the increase in the RMF, the eutectic grains are fragmented and gradually refined until a transition from coarser plate-like structure to a fine fibrous eutectic structure for the alloy. It was found that with the increasing of RMF, lambda decreases but HV, sigma and rho increase. The enthalpy of fusion (Delta H) and specific heat (C-p) for the same alloy was determined by means of differential scanning calorimetry from the heating trace during the transformation from the eutectic liquid to eutectic solid. The results obtained in the present work were compared with published data available in the literature.
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    Determination of mechanical, electrical and thermal properties of the Sn-Bi-Zn ternary alloy
    (ELSEVIER SCIENCE BV, 2011) Cadirli, Emin; Boyuk, Ugur; Kaya, Hasan; Marasli, Necmettin
    The development of lead-free solders has emerged as one of the key issues in the electronics packaging industries. Sn-Zn-Bi eutectic alloy has been considered as one of the lead-free solder materials that can replace the toxic Pb-Sn eutectic solder without increasing soldering temperature. This study investigates the effect of temperature gradient and growth rate on the mechanical, electrical and thermal properties of the Sn-Zn-Bi eutectic alloy. Sn-23 wt.% Bi-5 wt.% Zn alloy was directionally solidified upward with different growth rates (V = 8.3-478.6 mu m/s) at a constant temperature gradient (G = 3.99 K/mm) and with different temperature gradients (G = 1.78-3.99 K/mm) at a constant growth rate (V = 8.3 mu m/s) in the Bridgman-type growth apparatus. The microhardness (HV), tensile stress (sigma(t)) and compressive stress (sigma(c)) were measured from directionally solidified samples. The dependency of the HV, sigma(t), and sigma(c) for directionally solidified Sn-23 wt.% Bi-5 wt.% Zn alloy on the solidification parameters (G, V) were investigated and the relationships between them were obtained by using regression analysis. According to present results. HV, sigma(t) and sigma(c) of directionally solidified Sn-23 wt.% Bi-5 wt.% Zn alloy increase with increasing G and V. Variations of electrical resistivity (rho) for cast samples with the temperature in the range of 300-420 K were also measured by using a standard dc four-point probe technique. The enthalpy of fusion (Delta H) and specific heat (C-p) for same alloy was also determined by means of differential scanning calorimeter (DSC) from heating trace during the transformation from eutectic liquid to eutectic solid. (C) 2011 Elsevier B.V. All rights reserved.
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    Effect of Growth Velocity and Zn Content on Microhardness in Directionally Solidified Al-Zn Alloys
    (Univ Fed Sao Carlos, Dept Engenharia Materials, 2018) Acer, Emine; Cadirli, Emin; Erol, Harun; Kaya, Hasan; Sahin, Mevlut; Gunduz, Mehmet
    In this study, Al-xZn (x=1, 3, 5, 7, 10 and 20 wt. %) alloys were prepared using metals of 99.99% high purity in the vacuum atmosphere. These alloys were directionally solidified upward with a constant temperature gradient, G (10.3 K/mm) and different growth velocities (V) between 8.25 and 165 mu m/s in the directional solidification apparatus. The experimental results have revealed that with the increase of the growth velocity of the melts from 8.25 mu m/s to 165 mu m/s, the microstructures undergo a transition from cellular/cellular dendritic morphology to coarse dendritic form for each composition (Zn content, C-o). The measurements of microhardness (HV) of the specimens were performed by using a microhardness test device. The dependence of HV on V and C(o )was analyzed, and it has been found that with increasing the V and C-o the HV increases. Relationships between HV-V and HV-C-o were obtained by linear regression analysis, and the experimental results were compared with the results of previous similar works.
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    Effect of growth velocity on microstructure and mechanical properties of directionally solidified 7075 alloy
    (Taylor & Francis Ltd, 2020) Cadirli, Emin; Nergiz, Emel; Kaya, Hasan; Buyuk, Ugur; Sahin, Mevlut; Gunduz, Mehmet
    7075 alloys were prepared using metals of 99.99% high purity in the vacuum atmosphere. These alloys were directionally solidified upwards under various growth velocities (8.3-166.0 mu m/s) using a Bridgman-type directional solidification furnace. Dendritic spacings (lambda(1), lambda(2)) and microhardness (HV) were measured from both longitudinal and transverse sections of the samples. Ultimate tensile strength (sigma(U)) and yield strength (sigma(y)) of the solidified samples at room temperature were examined. The HV increased from 75.2 to 112.8 MPa, the sigma(U) increased from 155.8 to 210.1 MPa, and the sigma(y) increased from 198.4 to 319.8 MPa with increasing growth velocity from 8.3 to 166.0 mu m/s. Exponent values of the V for the lambda(1), lambda(2), HV, sigma(U) and sigma(y) were calculated as 0.27, 0.41, 0.05, 0.11 and 0.15, respectively. The results show that the hot tearing in the 7075 alloy is caused by the fracture of dendrites structures.
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    Effect of Heat Treatment on the Microstructures and Mechanical Properties of Al-4Cu-1.5Mg Alloy
    (Springer Int Publ Ag, 2022) Cadirli, Emin; Kaya, Hasan; Buyuk, Ugur; Ustun, Erkan; Gunduz, Mehmet
    In this work, the influence of different heat treatments (HT) processes on the microstructure and mechanical properties of cast Al-4Mg-1.5 Mg alloy was investigated. To investigate the effect of HT, firstly Al-4Cu-1.5Mg samples were homogenized (solution treatment) at 500 degrees C/2h, water quenched at room temperature (RT) and then immediately exposed to an artificial aging process at 200 degrees C for various aging times of 1, 4, 8, 12, 16, 20 and 24 hours. Quantitative examinations after HT processes (solution treatment and aging) have shown that intermetallic phases (Al2Cu and Al2CuMg) were dissolved in the alpha-Al matrix phase and distributed along the grain boundary. Some mechanical properties (HV sigma, sigma(TYS), sigma(UTS), sigma(CYS), E and delta) of a sufficient number of alloy samples exposed to different heat treatments were examined in detail. The data obtained show that the conditions of solution treatment and aging in some conditions show superior mechanical properties than the sample in the form as-cast. The highest microhardness value (126 HV) was obtained for the alpha-Al matrix phase, which was subjected to solution treatment (only homogenization). After aging for 1h at 200 degrees C, the peak value of microhardness was achieved as 289.5 HV for intermetallic phases. The highest tensile strength (sigma(UTS)) was obtained as 328 MPa for the sample which aged for 8h at 200 degrees C after solution treatment for 2h at 500 degrees C.
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    EFFECT OF HEAT TREATMENT ON THE MICROSTRUCTURES AND MECHANICAL PROPERTIES OF AL-4CU-1.5MG ALLOY (vol 16, pg 1020, 2021)
    (Springer Int Publ Ag, 2024) Cadirli, Emin; Kaya, Hasan; Buyuk, Ugur; Ustun, Erkan; Gunduz, Mehmet
    [Abstract Not Available]
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    Effect of rotating magnetic field on the microstructures and physical properties of Al-Cu-Co ternary eutectic alloy
    (ELSEVIER SCIENCE SA, 2015) Cadirli, Emin; Kaya, Hasan; Raebiger, Dirk; Eckert, Sven; Gunduz, Mehmet
    The solidification microstructures and physical properties of Al-Cu-Co ternary eutectic alloy were studied in a rotating magnetic field (RMF). The RMF-driven flow was the key factor causing grain refinement and uniformity of solidification microstructures. The temperature distributions during solidification were recorded under the conditions with and without RMF. The dependence of the eutectic spacing (lambda), the microhardness (HV), tensile strength (sigma(t)) and compressive strength (sigma(c)) on the RMF were investigated. Electrical resistivity (rho) measurements of the studied alloy were also performed by using the four-point probe method and the dependence of the resistivity on temperature and RMF were determined. Besides, the enthalpy (Delta H) and the specific heat (C-p) values were determined by the differential scanning calorimeter (DSC) analysis. Important changes were found in the microstructure, microhardness, tensile strength, compressive strength and electrical resistivity of the studied alloy with increasing RMF. (C) 2015 Elsevier B.V. All rights reserved.
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    Effect of silicon content on microstructure, mechanical and electrical properties of the directionally solidified Al-based quaternary alloys
    (Elsevier Science Sa, 2017) Cadirli, Emin; Buyuk, Ugur; Engin, Sevda; Kaya, Hasan
    Effect of silicon content on the microstructure (lamellar and flake), mechanical (microhardness, ultimate tensile strength) and electrical resistivity properties of Al-Cu-Fe-Si quaternary alloys has been investigated. Al-26Cu-0.5Fe-xSi (x = 6.5, 8, 10, 12 and 14 wt %) were prepared using metals of 99.99% high purity in the vacuum atmosphere. These alloys were directionally solidified under constant temperature gradient (8.50 Minim) and growth rate (8.25 mu m/s) by using a Bridgman type directional solidification furnace. Eutectic spacing, microhardness, ultimate tensile strength and electrical resistivity were expressed as functions of composition. The dependency of the eutectic spacing, microhardness, tensile strength and electrical resistivity on the composition (Si content) were determined. According to experimental results, the microhardness, ultimate tensile strength and electrical resistivity of the solidified samples increase with increasing the Si content, but decrease eutectic spacing. Variation of electrical resistivity with the temperature in the range of 300-650 K for studied alloys was also measured by using a standard d.c. four point probe technique. (C) 2016 Elsevier B.V. All rights reserved.
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    Interfacial energy of solid bismuth in equilibrium with Bi-In eutectic liquid at 109.5 degrees C equilibrating temperature
    (KOREAN INST METALS MATERIALS, 2008) Ocak, Yavuz; Akbulut, Sezen; Marasli, Necmettin; Keslioglu, Kazim; Boeyuk, Ugur; Kaya, Hasan; Cadirli, Emin
    The interfacial energy of solid bismuth (Bi) in equilibrium with Bi-In eutectic liquid was determined for the equilibrating temperature of 109.5 degrees C. A radial temperature gradient on the sample was established by heating it from the center with a single heating wire and cooling the outside of the sample at -10 degrees C with a heating/refrigerating circulating bath containing an aqueous ethylene glycol solution. The equilibrated grain boundary groove shapes of solid Bi in equilibrium with Bi In eutectic liquid (Bi- 47.3 at.%In) were observed from a sample quenched at 109.5 degrees C. The Gibbs-Thomson coefficient and the solid-liquid interfacial energy of the solid Bi in equilibrium with Bi In eutectic liquid were determined to be (8.4 +/- 0.4) x 10(-8) K in and (54.0 +/- 5.4) x 10(-3) J m(-2) from the observed grain boundary groove shapes. The grain boundary energy of the solid Bi phase was calculated to be (105.5 +/- 11.6) x 10(-3) J m(-2) by considering a force balance at the grain boundary grooves. The thermal conductivities of Bi-47.3 at.%In eutectic liquid phase and the solid Bi-47.3 at.%In phase and their ratio at 109.5 degrees C were measured with a radial heat flow apparatus and a Bridgman type growth apparatus.
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    Investigation of the Some Physical Properties of the Directionally Solidified Al-Cu-Co Ternary Eutectic Alloy
    (SPRINGER INDIA, 2015) Cadirli, Emin; Yilmazer, Izzettin; Sahin, Mevlut; Kaya, Hasan
    The Al-23.9% Cu-1.2% Co (wt%) ternary eutectic alloy was prepared using a vacuum melting furnace and a casting furnace. The samples were directionally solidified upwards at a constant growth velocity (18.8 mu m/s) under different temperature gradients (1.23-5.66 K/mm) and at a constant temperature gradient (5.66 K/mm) under different growth velocities (8.3-166 mu m/s) in a Bridgman-type directional solidification furnace. The dependence of the eutectic spacing on the solidification parameters (temperature gradient and growth rate) and that of the microhardness and compressive strength on the eutectic spacing and solidification parameters were investigated. The electrical resistivity measurements of the studied alloy were performed and the temperature coefficient of the resistivity was calculated from the curve of the resulting rho-Icurrency sign plot. The thermal conductivities of the sample grown at a constant temperature gradient and growth rate were obtained using the Wiedemann-Franz and Smith-Palmer equations.
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    Mechanical properties of directionally solidified lead-antimony alloys
    (SPRINGER, 2011) Sahin, Mevlut; Kaya, Hasan
    The Pb-17w% Sb alloy was directionally solidified under two solidification conditions: with different temperature gradients (G=0.93-3.67 K/mm) at a constant growth rate (V=17.50 mu m/s) and with different growth rates (V=8.3-497 mu m/s) at a constant temperature gradient (G=3.67 K/mm) in a Bridgman furnace. Microstructure parameters, such as primary dendrite arm spacing (lambda(1)), secondary dendrite arm spacing (lambda(2)), and dendrite tip radius (R), were measured. The microhardness (Hv) and ultimate tensile strength (sigma) of the directional solidification samples were also measured. The influences of solidification and microstructure parameters on Hv and sigma were investigated. The results obtained in this work were compared with similar experimental researches in literatures. It is shown that the Hv and sigma values increase with the increase of G and V, but decrease with the increase of lambda(1), lambda(2), and R.
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    Microstructural, Mechanical, Electrical, and Thermal Properties of the Bi-Sn-Ag Ternary Eutectic Alloy
    (Wuhan Univ Technology, 2017) Kaya, Hasan; Engin, Sevda; Aker, Aynur; Buyuk, Ugur; Cadirli, Emin
    The development of lead-free solders has emerged as one of the key issues in the electronics packaging industries. Bi-Sn-Ag eutectic alloy has been considered as one of the lead-free solder materials that can replace the toxic Pb-Sn eutectic solder without increasing soldering temperature. We investigated the effects of temperature gradient and growth rate on the mechanical, electrical and thermal properties of the Bi-Sn-Ag ternary eutectic alloy. Bi-47 wt% Sn-0.68 wt% Ag alloy was directionally solidified upward with different temperature gradients ( G=2.33-5.66 K/mm) at a constant growth rate ( V=13.25 mu m/s) and with different growth rates ( V=6.55-132.83 mu m/s) at a constant temperature gradient ( G=2.33 K/mm) in the growth apparatus. The microstructures (lambda), microhardness ( HV), tensile stress ( sigma), electrical resistivity (rho), and thermal properties (Delta H, C-p, T-m) were measured on directionally solidified samples. The dependency of the lambda, HV, sigma, and rho on G and V was investigated. According to the experimental results, lambda values decrease with increasing G and V, but HV, lambda, and rho values increase with increasing G and V. Variations of electrical resistivity (rho) for cast samples with the temperature in the range of 300-400 K were also measured by using a standard dc four-point probe technique. The enthalpy of fusion (Delta H) and specific heat ( C-p) for the same alloy was also determined by means of differential scanning calorimeter ( DSC) from heating trace during the transformation from eutectic liquid to eutectic solid.
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    The Effect of Growth Rate on the Microstructure and Mechanical Properties of 7020 Alloys
    (Springer, 2022) Kaya, Hasan; Buyuk, Ugur; Cadirli, Emin; Sahin, Mevlut; Gunduz, Mehmet
    The 7020 aluminum alloy is one of the hardenable Al-Zn-Mg based alloys, which are a family of high strength aluminum alloys. These 7020 alloys are commonly used in the aircraft and automotive industries. The microstructural changes have a significant impact on the mechanical properties of binary and multi-component alloys. For this reason, 7020 aluminum alloys were prepared with different growth rates on account of the changes in the microstructures; thus, directionally solidification processes were actualized with a Bridgman furnace at five various growth rates (V = 8.3-166.0 mu m/s) and at constant temperature gradient (G = 8.3 K/mm). Microhardness (HV), ultimate tensile strength (sigma(U)) and yield strength (sigma(y)) of the solidified alloys were determined. The HV increased from 758.8 to 917.1 N/mm(2), the sigma(U) from 125.4 to 208.1 N/mm(2) and the sigma(y) from 133.7 to 230.8 N/mm(2) with an increase in growth rate from 8.3 to 166.0 mu m/s.
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    Unidirectional solidification of Zn-rich Zn-Cu hypoperitectic alloy
    (MATERIALS RESEARCH SOC, 2009) Kaya, Hasan; Engin, Sevda; Boyuk, Ugur; Cadirli, Emin; Marasli, Necmettin
    Zn-0.7 wt% Cu-hypoperitectic alloy was prepared in a graphite crucible under a vacuum atmosphere. Unidirectional solidification of the Zn-0.7 wt% Cu-hypoperitectic alloy was carried out by using a Bridgman-type directional solidification apparatus under two different conditions: (i) with different temperature gradients (G = 3.85-9.95 K/mm) at a constant growth rate (41.63 mu m/s) and (ii) with different growth rate ranges (G = 8.33-435.67 mu m/s) at a constant temperature gradient (3.85 K/mm). The microstructures of the directionally solidified Zn-0.7 wt% Cu-hypoperitectic samples were observed to be a cellular structure. From both transverse and longitudinal sections of the samples, cellular spacing (lambda) and cell-tip radius (R) were measured. The effects of solidification-processing parameters (G and V) on the microstructure parameters (lambda and R) were obtained by using a linear regression analysis. The present experimental results were also compared with the current theoretical and numerical models and similar previous experimental results.