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    Directional solidification of the aluminium-copper eutectic alloy
    (JAPAN INST METALS, 1999) Cadirli, E; Ulgen, A; Gunduz, M
    Aluminium-copper of (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, and different temperature gradients G, and also with a constant temperature gradient and different growth rates in the Bridgman type directional solidification furnace. The lamellar spacings lambda(E) were measured from both transverse section and longitudinal section of the specimen. The undercooling values Delta T were obtained by using growth rate and system parameters K-1, K-2. It was found that the values of lambda(E) decreased as V, G and GV values are increased. The relationships between lamellar lambda(E)(2)V spacing lambda(E) and solidification parameters, V, G and GV were obtained by Least squares analysis. Bulk growth rate lambda(E)(2)V, was determined by using lambda(E) values for both the transverse section and the longitudinal section. The experimentally obtained values found were in good agreement with theoretical 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.