Journal of Korea Foundry Society (한국주조공학회지)

Korea Foundry Society (한국주조공학회)
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The Effect of Re addition and Solidification Rate on the Directional Solidification Behavior of Ni-Al Alloy

Ni-Al 합금의 일방향 응고 거동에 미치는 Re 및 응고속도의 영향

  • Lee, Man-Gil (Dept. of Metallurgy and Materials Science, Changwon University) ;
  • Yoo, Young-Soo (High Temperature Materials Group, Korea Institute of Materials Science) ;
  • Jo, Chang-Yong (High Temperature Materials Group, Korea Institute of Materials Science) ;
  • Lee, Je-Hyun (Dept. of Metallurgy and Materials Science, Changwon University)
  • 이만길 (창원대학교 금속재료공학과) ;
  • 유영수 (한국기계연구원 부설 재료연구소) ;
  • 조창용 (한국기계연구원 부설 재료연구소) ;
  • 이재현 (창원대학교 금속재료공학과)
  • Published : 2007.11.20
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Abstract

The effect of Re addition and solidification rate on the directional solidification behavior of Ni-Al model alloy has been investigated. Directional solidification (DS) were carried out using the modified Bridgman furnace with various solidification rates. The solid/liquid interface during directional solidification was preserved by quenching the specimen after the desired volume fraction of original liquid was solidified. The equilibrium partition coefficients of Al and Re Were estimated by measuring the compositions at the quenched solid/liquid interface. Then, the effect of Re addition on the elemental segregation behavior was carefully analyzed. The differential scanning calorimetry results showed that the Re addition results in increased ${\gamma}'$ solvus and freezing range of the alloy. It was also shown that the primary dendrite arm spacing gradually decreases with increasing the Re content, while the secondary dendrite arm spacing appears to be independent on the Re content. The compositional analyses clearly revealed that the segregation of Al increased with increasing the Re content and solidification rate, while that of Re was found to be independent on the solidification rate in the range of $10{\sim}100{\mu}m/s$ due to its sluggish diffusion rate in the Ni solid solution.

Keywords

References

  1. F. L. Versnyder and R.W. Guard: Trans. ASM, 'Directional Grain Structures for High Temperature Strength', vol. 52 (1960) pp.485-493
  2. B. B. Seth: Superalloys 2000, Eds. by T.M. Pollock et al., 'Superalloys-The Utility Gas Turbine Perspective', TMS, Warrendale, PA, (2000) pp. 3-16
  3. M. C. Flemings: Solidification Processing, McGraw-Hill, NY, USA (1974) p. 32
  4. W. F. Gale and T. C. Totemeier: Smithells Metals Reference Book, vol. 1, Elsevier Butterworth-Heinemann publ., MA, USA (2004) p. 11-437
  5. W. Kurz and D. J. Fisher: Fundamentals of Solidification, Trans Tech Publ., Switzerland (1998) p. 54
  6. M. McLean: Directionally Solidified Materials for High Temperature Service, The Metals Society, London, UK (1983) p. 20
  7. H. K. Kim, J. C. Earthrnan, and E. J. Lavernia: Mater. Sci. Eng. A, 'Primary Dendrite Arm Spacings and Tip Radii in Directionally Solidified $Ni_3Al$', vol. A152 (1992) pp. 240-246
  8. D. A. Porter and K. E. Easterling: Phase Transformations in Metals and Alloys, Chapman and Hall, London, UK (1992) p. 221