Role of Re and Co on microstructures and γ′ coarsening in single crystal superalloys

Wang, W.Z.; Jin, Tao; Liu, J.L.; Sun, Xiaofeng; Guan, H.R.; Hu, Z.Q.

doi:10.1016/j.msea.2007.06.031

Cited by 93 publications

(40 citation statements)

References 15 publications

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“…Rae's study suggested that Co suppressed the nucleation of the σ phase by altering the γ lattice parameter, which was attributed to the redistribution of elements between γ and γ phases [6]. Wang's work on a series of single crystal superalloys also demonstrated that TCP phase formation was suppressed by promoting the diffusion process due to more Co additions [12]. In the current study, higher Co addition was showed to be beneficial for the suppression of TCP phase formation, which was attributed to its influence on the elemental partitioning behavior of the TCP-forming elements such as Re, Cr, Mo and W (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…However, the mechanism is not quite clear yet, and more Ru additions increase the cost of new generation single crystal superalloys. Furthermore, Co additions were found to prevent the formation of TCP phases in some superalloys [8,[10][11][12], although there has been still controversy associated with the effect of Co additions on microstructural stability [13,14].…”

Section: Introductionmentioning

confidence: 99%

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Compositional effect on TCP phase formation in Ru-containing Ni-based single crystal superalloys

Shi

Huo

Cao

et al. 2014

MATEC Web of Conferences

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Abstract. Microstructural instability involving the formation of topologically close-packed (TCP) phases is restricted during the alloy development of Ni-based single crystal superalloys. In this study, the effects of alloying elements including Co, Cr, Mo and Ru on the formation of different TCP phases were investigated in a series of single crystal superalloys. Experimental results showed that more additions of Cr and Mo promoted the TCP phase formation, while Co and Ru played a positive role in improving microstructural stability. It is indicated that σ , P and R phases existed with various morphology and compositions in different experimental alloys during thermal exposure at 1100• C. The content of Co, Cr and Mo in those alloys affected the types of TCP phases significantly, while Ru additions showed a negligible effect. R phase was prone to form in alloys containing high level of Co addition. Meanwhile, the ratio of Cr and Mo content had strong influence on the formation of σ and P phases in alloys containing low level of Co addition. The effects of alloying additions on the elemental partitioning ratios between γ and γ phases contributed to their corresponding influence on TCP phase formation.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Compositional effect on TCP phase formation in Ru-containing Ni-based single crystal superalloys

Shi

Huo

Cao

et al. 2014

MATEC Web of Conferences

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“…Mo appear to stabilise the P phase [5]. While cobalt is one of the constituents of the TCP phase and therefore higher Co addition is expected to increase the propensity to TCP phase formation, the opposite effect has been found in various studies [7]. In a study by Wang et al investigating the effects of Co and Re on TCP phase formation in a series of Re-containing alloys, it was found that addition of 3 wt% Co suppresses TCP phase formation after 1000 hours at 1050°C and the addition of 12wt% Co suppresses TCP phase precipitation after 2000 hours at 1050°C.…”

Section: Discussionmentioning

confidence: 93%

“…Without the cobalt addition, TCP phase formation was observed after 500 hours exposure at 1050°C. The authors argued that cobalt accelerates the diffusion of other elements including the TCP forming elements, thus reducing the segregation of these elements and thereby retarding TCP phase formation [7]. In another study investigating TCP phase formation in Re-containing alloys, doubling the cobalt content at the expense of nickel was also found to significantly reduce the amount the σ phase precipitated [5].…”

Section: Discussionmentioning

confidence: 99%

A Study of the Effects of Alloying Additions on TCP Phase Formation in 4<sup>th</sup> Generation Nickel-Base Single-Crystal Superalloys

Pang

Hobbs

Stone

et al. 2011

AMR

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Abstract. The demand for higher engine operating temperatures to improve aeroengine efficiency has meant that increasing levels of alloying additions are being added to single-crystal nickel-base superalloys for turbine blades applications. Whilst better mechanical and environmental performance may be obtained with these alloying additions, they also destabilise the alloys forming topologically closed-packed (TCP) phases. In this study, the formation of TCP phases has been studied in a series of four alloys designated LDSX1-4 which have a systematic variation in the levels of Co, Mo and W. The alloys were exposed to elevated temperatures between 900-1100°C for up to 1000 hours. This was followed by detailed analysis of the microstructures in the SEM. Identification of the TCP phases in selected alloys was also carried out. The effects of each alloying addition on TCP phase formation is discussed in light of these results.

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“…These four alloying elements were chosen since they are known to be important elements for next generation nickel-base superalloys. Ru, Co and especially W and Mo improve the creep strength and additionally both Ru and Co stabilize the γ/γ′ microstructure against TCP precipitation [3,4]. This study was performed to isolate the effect of these four elements as well as their interaction with each other, since elements like Ru can influence the partitioning behavior of other alloying elements [5,6,7].…”

Section: Introductionmentioning

confidence: 99%

Lattice Misfit of High Refractory Ruthenium Containing Nickel-Base Superalloys

Neumeier

Ang

Hobbs

et al. 2011

AMR

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The influence of Ru, Co, Mo and W on the lattice misfit of eight highly alloyed Re containing single crystal nickel-base superalloys was investigated. High resolution X-ray diffraction (XRD) was used to relate the elemental partitioning behavior and the Vegard coefficients of the elements under investigation to the measured lattice parameter of the γ and γ′ phase. The residual chemical segregation and especially the coherency stress-induced tetragonal distortion of the γ matrix lattice in the high Mo containing alloys results in the observation of two different lattice parameters for the γ matrix phase. This leads to three overlapping, but clearly distinguishable {002} X-ray reflections.

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Role of Re and Co on microstructures and γ′ coarsening in single crystal superalloys

Cited by 93 publications

References 15 publications

Compositional effect on TCP phase formation in Ru-containing Ni-based single crystal superalloys

Compositional effect on TCP phase formation in Ru-containing Ni-based single crystal superalloys

A Study of the Effects of Alloying Additions on TCP Phase Formation in 4<sup>th</sup> Generation Nickel-Base Single-Crystal Superalloys

Lattice Misfit of High Refractory Ruthenium Containing Nickel-Base Superalloys

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