日本金属学会誌

J. Japan Inst. Metals, Vol. 67, No. 11 (2003),
pp. 675-680

Solidification Process and Behavior of Alloying Elements in Ni-based Superalloy INCONEL718

Seung-Hun Kang1,, Yuho Deguchi1,\footnotemark[1], Kaoru Yamamoto2, Keisaku Ogi2 and Makoto Shirai3

1Department of Materials Science and Engineering, Graduate School of Engineering, Kyushu University, Fukuoka 812-8581
2Department of Materials Science and Engineering, Faculty of Engineering, Kyushu University, Fukuoka 812-8581

3National Space Development Agency of Japan, Tsukuba 305-8505

Abstract:

The thermal and metallographic analysis revealed that the solidification of Inconel 718 alloy proceeds in order of primary γ at 1615 K, γ/NbC eutectic at 1561 K, and γ/Ni2Nb eutectic at 1452 K. On the other hand, equilibrium evaluation using Thermo-Calc expresses the following solidification sequences; primary γ at 1633 K, followed by γ/NbC eutectic at 1555 K. The γ/Ni2Nb eutectic phase doesn't appear in the equilibrium calculation, indicating that the γ/Ni2Nb phase crystallizes as non equilibrium eutectic phase.

The partition coefficients of alloying elements to primary γ and eutectic phases were also determined experimentally (k(Exp.)) and compared with the values estimated with Thermo-Calc (k(T-C)). The behaviors of alloying elements during solidification were estimated by using k(Exp.) and k(T-C) on the Clyne-Kurz model. It was found that both of them are in a good agreement.


(Received July 7, 2003)

Keywords:

solidification, nickel-based superalloy, partition coefficient, Thermo-Calc, segregation


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