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    Experimental investigation of the effect of solidification processing parameters on the rod spacings in the Sn-1.2 wt.% Cu alloy
    (ELSEVIER SCIENCE SA, 2009) Cadirli, E.; Boyuk, U.; Engin, S.; Kaya, H.; Marasli, N.; Ulgen, A.
    Sn-1.2 wt.% Cu alloy was prepared in a graphite crucible under the vacuum atmosphere. The samples were directionally solidified upwards under argon atmosphere with different temperature gradients (G = 2.69-8.88 K/mm) at a constant growth rate (V = 6.80 mu m/s) and with different growth rates (V = 2.78-136.36 mu m/s) at a constant temperature gradient (G = 2.69 K/mm) by using a Bridgman-type directional solidification apparatus. The microstructure of Sn-1.2 wt.% Cu alloy seems to be rod eutectic structure. The rod spacings (lambda) were measured from both transverse and longitudinal sections of the samples. The influence of the growth rate (V) and temperature gradient (G) on the rod spacings (lambda) and undercoolings (Delta T) was analysed. The values of lambda(2)V, lambda(2)G, Delta T lambda, Delta TV(-0.5) and Delta TG(0.5) were determined by using the Jackson-Hunt eutectic theory. The results obtained in the present work have been compared with the similar experimental results obtained in the previous works for binary alloys. (C) 2009 Elsevier B.V. All rights reserved.
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    Investigation of the effect of composition on microhardness and determination of thermo-physical properties in the Zn-Cu alloys
    (ELSEVIER SCI LTD, 2011) Kaya, H.; Cadirli, E.; Ulgen, A.
    Zinc-copper of (99.99%) high purity alloys were directionally solidified upward with different compositions, C-o, Zn-(0.7,1.5, 2.4 and 7.37) wt.% Cu under two different solidification conditions (G = 3.85 K/mm, V = 0.0083 mm/s and G = 8.70 K/mm, V = 0.436 mm/s) using a Bridgman type directional solidification apparatus. The measurements of microhardness of directionally solidified samples were made by using a microhardness test device. The dependence of microhardness (HV) on composition was analyzed. According to these results, it has been found that the values of HV increase with the increasing Cu content (C-o). Variation of electrical resistivity (rho) and electrical conductivity (sigma) with the temperature were also measured by using a standard d.c. four-point probe technique. The enthalpy of fusion (Delta H) and specific heat (Cp) of the Zn-Cu alloys were determined from heating curve during the transformation from solid to liquid phase by using differential scanning calorimeter (DSC). (C) 2010 Elsevier Ltd. All rights reserved.
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    Investigation of the effect of solidification processing parameters on microhardness and determination of thermo-physical properties in the Zn-Cu peritectic alloy
    (ELSEVIER SCIENCE SA, 2010) Boyuk, U.; Kaya, H.; Cadirli, E.; Marasli, N.; Ulgen, A.
    Zn-1.5wt.% Cu peritectic alloy was directionally solidified upward with different growth rates (8.41-661.11 mu m/s) at a constant temperature gradient (7.81 K/mm) and with different temperature gradients (1.99-7.81 K/mm) at a constant growth rate (16.44 mu m/s) using a Bridgman-type directional solidification apparatus. The measurements of microhardness of directionally solidified samples were made by using a microhardness test device. The dependence of microhardness (HV) on the growth rate (V) and temperature gradient (G) were analyzed. According to these results, it has been found that with the increasing the values of V and G the values of HV increase. Variation of electrical resistivity (rho) and electrical conductivity (sigma) with the temperature in the range of 300 similar to 670 K for casting samples were also measured by using a standard d.c. four-point probe technique. The variation of Lorenz coefficient with the temperature was determined by using the measured values of electrical conductivity and thermal conductivity. The enthalpy of fusion and specific heat for same alloy were determined by means of differential scanning calorimeter (DSC) from the heating curve during the transformation from peritectic solid to peritectic liquid. (C) 2009 Elsevier B.V. All rights reserved.
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    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
    (SPRINGER, 2010) Cadirli, E.; Boyuk, U.; Engin, S.; Kaya, H.; Marasli, N.; Keslioglu, K.; Ulgen, A.
    Sn-3 wt% Cu hypereutectic alloy was prepared in a graphite crucible under the vacuum atmosphere. The samples were directionally solidified upwards under argon atmosphere with different temperature gradients (G = 4.24-8.09 K/mm) at a constant growth rate (V = 7.64 mu m/s) and with different growth rates (V = 2.24-133.33 mu m/s) at a constant temperature gradient (G = 4.24 K/mm) by using a Bridgman type directional solidification apparatus. The microstructure of directional solidified Sn-3 wt% Cu alloy seems to be rod eutectic structure. The influence of the growth rate (V) and temperature gradient (G) on the rod spacing (lambda) and undercooling (Delta T) were analysed. The values of lambda(2)V, lambda(2)G, Delta T lambda, Delta TV(-0.5) and Delta TG(-0.5) were determined by using the Jackson-Hunt eutectic theory. The dependence of microhardness (HV) on the rod spacing (lambda) was analyzed. According to present results, it has been found that the value of HV increases with the increasing the value of lambda.