Effect of growth rates and temperature gradients on the lamellar spacing and the undercooling in the directionally solidified Pb-Cd eutectic alloy


Çadırlı E. , Kaya H. , Gündüz M.

MATERIALS RESEARCH BULLETIN, cilt.38, ss.1457-1476, 2003 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 38
  • Basım Tarihi: 2003
  • Doi Numarası: 10.1016/s0025-5408(03)00169-7
  • Dergi Adı: MATERIALS RESEARCH BULLETIN
  • Sayfa Sayıları: ss.1457-1476

Özet

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.
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 mm/s, and different temperature gradients G (1.6–6.4 K/mm range), and also with a constant temperature gradient (6.4 K/mm) and different growth rates V (8.3–165.5 mm/s range) in the Bridgman-type directional solidification furnace. The lamellar spacings l were measured from both transverse section and longitudinal section of the specimen. The variations of l with respect to G and V were determined by using linear regression analysis. The dependence of l on DTe (the extremum undercooling) was also analysed. The variation of DTe with V at constant G and with G at constant V were investigated. According to these results, it has been found that l decreases with the increasing values of G and V. Also DTe 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.