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Variation of Alloying Element Distribution and Microstructure due to Microsegregation in Ni-base Superalloy GTD 111

니켈기 초내열 합금 GTD 111에서 편석에 의한 합금원소 분포 및 미세조직 변화

Choi, Baig-Gyu;Kim, In-Soo;Do, Jeong-Hyeon;Jung, Joong-Eun;Jo, Chang-Yong
최백규;김인수;도정현;정중은;조창용

  • Received : 2015.10.30
  • Accepted : 2015.12.04
  • Published : 2015.12.31

Abstract

Segregation during solidification and homogenization during thermal exposure in GTD 111 were investigated. The microstructures of as-cast, standard heat-treated, and thermally exposed specimens were observed by SEM. A compositional analysis of each specimen was conducted by EDS. The dendrite core was enriched in W and Co, though lower levels of Ti and Ta were observed. An unexpected phase, in this case like the ${\eta}$ phase, was observed due to segregation near the ${\gamma}-{\gamma}^{\prime}$ eutectic in the standard heat-treated specimen. Segregation also induced microstructural evolution near the ${\gamma}-{\gamma}^{\prime}$ eutectic during the standard heat treatment. A quantitative analysis and microstructural observations showed that the thermal exposure at a high temperature enhanced the chemical homogeneity of the alloy.

Keywords

Ni-base superalloy;Segregation;Thermal exposure;Homogenization

References

  1. Sims CT, Stoloff NS, Hagel WC, Superalloys II, John Wiley & Sons, New York (1987).
  2. Reed RC, The Superalloys, Cambridge University Press, Cambridge (2006).
  3. H. E. Collins, Metall. Trans., "The Effect of Thermal Exposure on the Microstructure and Mechanical Properties of Nickel-Base Superalloys", 5 (1974) 189-204.
  4. Nazmy N and Staubli M, Scripta Metall. Mater., "Embrittlement of several nickel-base alloys after high-temperature exposure", 24 (1990) 135-138. https://doi.org/10.1016/0956-716X(90)90580-A
  5. Collins HE, Metall. Trans. A, "The effect of thermal exposure on the mechanical properties of the directionally solidified superalloy TRW-NASA VIA", 6A (1975) 515-530.
  6. Daleo JA and Wilson JR, J. Eng. Gas Turbines Power, "GTD111 Alloy Material Study", 120 (1998) 375-382. https://doi.org/10.1115/1.2818133
  7. Sajjadi SA and Natech S, Mater. Sci. Eng. A, "A high temperature deformation mechanism map for the high performance Ni-base superalloy GTD-111" 307 (2001) 158-164. https://doi.org/10.1016/S0921-5093(00)01822-0
  8. Sajjadi SA, Natech S and Guthrie RIL, Mater. Sci. Eng. A, "Study of microstructure and mechanical properties of high performance Ni-base superalloy GTD-111", 325 (2002) 484-489. https://doi.org/10.1016/S0921-5093(01)01709-9
  9. Natech S and Sajjadi SA, Mater. Sci. Eng. A, "Dislocation network formation during creep in Ni-base superalloy GTD-111" 339 (2003) 103-108. https://doi.org/10.1016/S0921-5093(02)00125-9
  10. Cheruvu NS, Proc. 2000 International Joint Power Generation Conference, "Oxidation and Gamma Particle Coarsening Behavior of IN-738 and GTD-111DS", American Society of Mechanical Engineers, Miami (2000) 551-558.
  11. Kearsey RM, Beddoes JC, Jones P and Au P, Intermetallics, "Compositional design considerations for microsegregation in single crystal superalloy systems", 12 (2004) 903-910. https://doi.org/10.1016/j.intermet.2004.02.041
  12. M. J. Starink and R. C. Thomson, J. Mater. Sci., "The effect of high temperature exposure on dendritic segregation in a conventionally cast Ni based superalloy", 36 (2001) 5603-5608. https://doi.org/10.1023/A:1012513615622
  13. M. Durand-Charre, The Microstructue of Superalloys, Gordon and Breach Science Pub., Amsterdam (1997).
  14. Chen QZ, Jones CN and Knowles DM, Scripta Mater., "Effect of alloying chemistry on MC carbide morphology in modified RR2072 and RR2086 SX superalloys" 47 (2002) 669-675. https://doi.org/10.1016/S1359-6462(02)00266-X
  15. Starink MJ, Cama H and Thomson RC, Scripta Mater., "MC Carbides in the Hf Containing Ni Based Superalloy MarM002" 38 (1998) 73-80.
  16. Chen J, Lee JH, Jo CY, Choe SJ and Lee YT, Mater. Sci. Eng. A, "MC carbide formation in directionally solidified MARM247 LC superalloy", 247 (1998) 113-125. https://doi.org/10.1016/S0921-5093(97)00761-2
  17. Choi BG, Kim IS, Kim DH and Jo CY, Mater. Sci. Eng. A, "Temperature dependence of MC decomposition behavior in Ni-base superalloy GTD 111", 478 (2008) 329-335. https://doi.org/10.1016/j.msea.2007.06.010
  18. Poerter DA and Easterking KE, Phase Transformation in Metals and Alloys, Chapman & Hall, London (1992).