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Vol.49, No.11, 882 ~ 893, 2011
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| Title |
| Effect of Re and Ru Addition on the Solidification and Solute Redistribution Behaviors of Ni-Base Superalloys |
| 서성문 Seong Moon Seo , 정희원 Hi Won Jeong , 이재현 Je Hyun Lee , 유영수 Young Soo Yoo , 조창용 Chang Yong Jo |
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| Abstract |
| The influence of rhenium (Re) and ruthenium (Ru) addition on the solidification and solute redistribution behaviors in advanced experimental Ni-base superalloys has been investigated. A series of model alloys with different levels of Re and Ru were designed based on the composition of Ni-6Al-8Ta and were prepared by vacuum arc melting of pure metallic elements. In order to identify the influence of Re and Ru addition on the thermo-physical properties, differential scanning calorimetry analyses were carried out. The results showed that Re addition marginally increases the liquidus temperature of the alloy. However, the γ` solvus was significantly increased at a rate of 8.2℃/wt.% by the addition of Re. Ru addition, on the other hand, displayed a much weaker effect on the thermo-physical properties or even no effect at all. The microsegregation behavior of solute elements was also quantitatively estimated by an electron probe microanalysis on a sample quenched during directional solidification of primary γ with the planar solid/liquid interface. It was found that increasing the Re content gradually increases the microsegregation tendency of Re into the dendritic core and γ` forming elements, such as Al and Ta, into the interdendritic area. The strongest effect of Ru addition was found to be Re segregation. Increasing the Ru content up to 6 wt.% significantly alleviated the microsegregation of Re, which resulted in a decrease of Re accumulation in the dendritic core. The influence of Ru on the microstructural stability toward the topologically close-packed phase formation was discussed based on Scheil type calculations with experimentally determined microsegregation results. |
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| Key Words |
| superalloys, solidification, segregation, electron probe microanalysis, ruthenium |
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