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    Dependency of the dendritic arm spacings and tip radius on the growth rate and composition in the directionally solidified succinonitrile-carbon tetrabromide alloys
    (ELSEVIER SCIENCE BV, 2005) Kaya, H; Cadirli, E; Keslioglu, K; Marasli, N
    Succinonitrile (SCN)-carbon tetrabromide (CTB) alloys for different concentrations of CTB (C(0)) were unidirectionally solidified with a constant temperature gradient (G = 7.5 K/mm) at different growth rates (V = 6.5-103.5 mu m/s). The primary dendrite arm spacings, secondary dendrite arm spacings and dendrite tip radius were measured as a function of growth rates and compositions. Theoretical models for the dendrite arm spacings 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 have also been made. (c) 2005 Elsevier B.V. All rights reserved.
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    Effect of growth rate and composition on the primary spacing, the dendrite tip radius and mushy zone depth in the directionally solidified succinonitrile-Salol alloys
    (ELSEVIER SCIENCE BV, 2003) Cadirli, E; Karaca, I; Kaya, H; Marasli, N
    The succinonitrile (SCN)-Salol alloys for four different concentrations Salol were unidirectionally solidified for five different growth rates in a constant temperature gradient. The microstructure parameters, viz., the primary dendrite arm spacing, lambda(1), dendrite tip radius, R and mushy zone depth, d, were measured. The dependence of the microstructure parameters on the solidification parameters for SCN-Salol alloys were determined by linear regression analysis. The results are compared with theoretical models and published data. (C) 2003 Elsevier Science B.V. All rights reserved.
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    Effect of growth rate and lamellar spacing on microhardness in the directionally solidified Pb-Cd, Sn-Zn and Bi-Cd eutectic alloys
    (SPRINGER, 2004) Kaya, H; Gunduz, M; Cadirli, E; Uzun, O
    Lead-cadmium, Zinc-tin and Bismuth-cadmium of (99.99%) high purity eutectic alloys were melted in a graphite crucible under vacuum atmosphere. These eutectic alloys were directionally solidified upward with a constant temperature gradient G and different growth rates V in the Bridgman type directional solidification furnace. The lamellar spacings lambda and microhardness H-V were measured from both transverse section and longitudinal section of the specimen. The variations of H-V with respect to V and lambda have been determined by using the linear regression analysis method. H-V values increase with the increasing values of V and decrease with the increasing lambda values. The Hall-petch type relationships obtained in this work have been compared with the previous works. (C) 2004 Kluwer Academic Publishers.
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    Effect of growth rates and temperature gradients on the lamellar spacing and the undercooling in the directionally solidified Pb-Cd eutectic alloy
    (PERGAMON-ELSEVIER SCIENCE LTD, 2003) Cadirli, E; Kaya, H; Gunduz, M
    Lead-cadmium of high (99.99%) purity eutectic alloy was melted in a graphite crucible under vacuum atmosphere. These regular eutectic alloys were directionally solidified upward with a constant growth rate of 8.3 mum/s, and different temperature gradients G (similar to1.6-6.4 K/mm range), and also with a constant temperature gradient (similar to6.4 K/mm) and different growth rates V (8.3-165.5 mum/s range) in the Bridgman-type directional solidification furnace. The lamellar spacings lambda were measured from both transverse section and longitudinal section of the specimen. The variations of lambda with respect to G and V were determined by using linear regression analysis. The dependence of lambda on DeltaT(e) (the extremum undercooling) was also analysed. The variation of DeltaT(e) with Vat constant G and with G at constant V were investigated. According to these results, it has been found that lambda decreases with the increasing values of G and V Also DeltaT(e) increases with increasing V for a constant G and with the increasing G for a given V, respectively. The results obtained in this work have been compared with the Jackson-Hunt eutectic theory and the previous experimental results. (C) 2003 Elsevier Ltd. All rights reserved.
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    Effect of growth rates and temperature gradients on the spacing and undercooling in the broken-lamellar eutectic growth (Sn-Zn eutectic system)
    (ASM INTERNATIONAL, 2003) Kaya, H; Cadirli, E; Gunduz, M
    The Sn-Zn system has a eutectic structure of a broken lamellar type. Dependence of the broken-lamellar spacing lambda and the undercooling DeltaT on V and G were investigated, and the relationship between them was examined. A Sn-Zn (99.99%) high-purity eutectic alloy was melted in a graphite crucible under vacuum atmosphere. This eutectic alloy was directionally solidified upward with a constant growth rate V (8.30 mum/s) and different temperature gradients G (1.86-6.52 K/mm), and also with a constant temperature gradient (6.52 K/mm) and different growth rates (8.30-165.13 mum/s) in a Bridgman-type directional solidification furnace. The lamellar spacings lambda were measured from both transverse and longitudinal sections of the specimen. The lambda values from the transverse section were used for calculations and comparisons with the previous works. The undercooling values DeltaT were obtained using growth rate and system parameters K-1 and K-2. It was found that the values of lambda decreased while V and G increased. The relationships between lamellar spacing lambda and solidification parameters V and G were obtained by linear regression analysis method. The lambda(2)V, DeltaTlambda, DeltaTV(-0.5), and lambda(3)G values were determined using lambda, DeltaT, V, and G values. The experimentally obtained values for the broken-lamellar growth (Sn-Zn eutectic system) were in good agreement with the theoretical and other experimental values.
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    Effect of the temperature gradient, growth rate, and the interflake spacing on the microhardness in the directionally solidified Al-Si eutectic alloy
    (ASM INTERNATIONAL, 2003) Kaya, H; Cadirli, E; Gunduz, M; Ulgen, A
    An alloy of composition Al-12.6 wt.% Si was prepared using metals of 99.99% purity. Weighed amounts of aluminium and silicon were melted in the vacuum-melting furnace. This irregular eutectic alloys were directionally solidified upward with a constant growth rate V (8.3 x 10(-3) mm/s) and different temperature gradients G (2.0-7.8 K/mm) and also with a constant temperature gradient G (7.8 K/mm) and different growth rates V (8.3-498.7 x 10(-3) mm/s) in the directional solidification furnace. The interflake spacings lambda and microhardness H-nu were measured from both transverse section and longitudinal section of the specimen. The variations of H, with respect to G, V, and lambda have been determined by using the linear regression analysis method. It has been shown that H-nu increases with the increasing values of G and V. On the other hand H-nu values decreases with the increasing lambda values. The Hall-Petch type relationships obtained in this work have been compared with the previous works.
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    Interflake spacings and undercoolings in Al-Si irregular eutectic alloy
    (ELSEVIER SCIENCE SA, 2004) Gunduz, M; Kaya, H; Cadirli, E; Ozmen, A
    Aluminium-silicon irregular eutectic alloy was melted in a graphite crucible in vacuum. This alloy was directionally solidified at a constant growth rate, V (8.3 mum/s) and at different temperature gradients, G (2.0-7.8 K/mm) and also with a constant G (7.8 K/mm) and different V (8.3-498.7 mum/s) in the Bridgman type directional solidification furnace. The interflake spacings, lambda(i), were measured from both transverse and longitudinal sections of the specimens. The relationships between interflake spacings, lambda(i) and solidification parameters V and G were obtained by linear regression analysis method. The variations of interflake spacings, lambda(i) with V, G and undercoolings, DeltaT(i), were investigated and the relationships between them were examined. Operating parameters phi and eta which reflect the spacing adjustment mechanism were obtained. lambda(i)(2)V, lambda(i) DeltaT(i), DeltaT(i)V(-a), lambda(i)(3)G and DeltaT(i)G(-b) values were determined by using lambda(i), V, G and DeltaT(i), values. The results obtained in this work have been compared with the eutectic theory and previous experimental results. (C) 2003 Elsevier B.V. All rights reserved.
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    Solid-liquid interfacial energy in the Al-Ti system
    (ELSEVIER SCIENCE BV, 2004) Keslioglu, K; Gunduz, M; Kaya, H; Cadirli, E
    The equilibrated grain boundary groove shapes for the Al-Ti peritectic system were directly observed. From the observed grain boundary groove shapes, the Gibbs-Thomson coefficient for solid Al in Al-Ti solution has been determined to be (1.281 +/- 0.06) x 10(-7) K in with a numerical method. The solid-liquid interface energy for solid Al in Al-Ti solution has been obtained to be (170.72 +/- 16.22) x 10(-3) J m(-2) from the Gibbs-Thomson equation. The grain boundary energy for the same material has been calculated to be (332.01 +/- 35.19) x 10(-3) J m(-2) from the observed grain boundary groove shapes. (C) 2004 Elsevier B.V. All rights reserved.