Coupling between Re segregation and γ/γ′ interfacial dislocations during high-temperature, low-stress creep of a nickel-based single-crystal superalloy

Huang, Ming; Cheng, Zhiqiang; Xiong, Jichun; Li, Jiarong; Hu, Jianqiao; Liu, Zhanli; Zhu, Jing

doi:10.1016/j.actamat.2014.05.033

Cited by 105 publications

(23 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2 clusters were neither detected by extended X-ray absorption fine structure investigations (EXAFS) nor by atom probe tomography (APT) [12,19,20]. Recent experiments show that Re atoms segregate to the core of network dislocations at γ/γ' interfaces and hence block their motion during creep deformation [21,22]. Till now, the observation of effects associated to Re has been confined either in the γ matrix phase or at the γ/γ' interfaces.…”

mentioning

confidence: 99%

On the segregation of Re at dislocations in the γ' phase of Ni-based single crystal superalloys

Makineni

Kontis

et al. 2018

Materialia

View full text Add to dashboard Cite

We report evidence of Re and Mo segregation (up to 2.6 at.% and 1 at.%) along with Cr and Co to the dislocations inside of γ' precipitates in a second generation Ni-based single crystal superalloy, after creep deformation at 750°C under an applied stress of 800 MPa. The observed segregation effects can be rationalized through bridging the solute partitioning behavior across the γ/γ' interface and the pipe diffusion mechanism along the core of the dislocation line. This understanding can provide new insights enabling improved alloy design. Tomography.Single crystal Ni-based superalloys have long been important engineering materials used in gas turbines and jet engines due to their superior creep, fatigue and oxidation properties at elevated temperatures [1][2][3][4][5][6][7]. These are associated with the two-phase microstructure, where a disordered face-centered cubic (FCC) γ matrix contains a high volume fraction of L1 2 ordered γ' precipitates, which have been considered initially as dislocation-free [3]. Many elements are typically added for solid solution strengthening of the γ matrix, such as W and Mo [8]. Re has attracted special attention due to the fact that additions of 2 to 6 wt.% Re significantly enhance the creep properties of Ni-based single crystal superalloys [1,3,[9][10][11]. How Re improves the creep properties is debated.The following possibilities have been suggested in the literature: (i) solid solution strengthening and distortions of the γ matrix lattice due to the large size of Re atoms [1,12], (ii) the slow diffusion rate of Re in Ni (slowest of all d-shell elements) [13,14], and (iii) the possible formation of Re clusters in the γ matrix that might hinder dislocation movement [15][16][17][18]. However, these Re

show abstract

mentioning

confidence: 99%

On the segregation of Re at dislocations in the γ' phase of Ni-based single crystal superalloys

Makineni

Kontis

et al. 2018

Materialia

View full text Add to dashboard Cite

show abstract

“…All of them to some degree or other will influence the mechanical properties of blades and may cause damage during operation. [5][6][7][8][9] The macroscopic inhomogeneity in crystal orientation (e.g., subgrain boundaries or misoriented bands of dendrites, bended during crystallization) may be one of the inherited defects. These defects are generally related to the crystallization of complex shape casts.…”

Section: Introductionmentioning

confidence: 99%

Influence of Heat Treatment on Defect Structures in Single-Crystalline Blade Roots Studied by X-ray Topography and Positron Annihilation Lifetime Spectroscopy

Krawczyk

Bogdanowicz

Hanc-Kuczkowska

et al. 2018

Metall Mater Trans A

View full text Add to dashboard Cite

Single-crystalline superalloy CMSX-4 is studied in the as-cast state and after heat treatment, with material being taken from turbine blade castings. The effect of the heat treatment on the defect structure of the root area near the selector/root connection is emphasized. Multiscale analysis is performed to correlate results obtained by X-ray topography and positron annihilation lifetime spectroscopy (PALS). Electron microscopy observations were also carried out to characterize the inhomogeneity in dendritic structure. The X-ray topography was used to compare defects of the misorientation nature, occurring in as-cast and treated states. The type and concentration of defects before and after heat treatment in different root areas were determined using the PALS method, which enables voids, mono-vacancies, and dislocations to be taken into account. In this way, differences in the concentration of defects caused by heat treatment are rationalized.

show abstract

“…On the other hand, μ phases contain high concentration of alloying elements especially Re and W, the elemental mapping results in Section 3.3 show that the enrichment of Re and W at grain boundaries disappeared after the precipitation of μ phases, Re and W are very important strengthening elements in the single crystal superalloys [32][33][34][35], so the consumption of strengthening elements at the grain boundaries could further weaken the superalloy. Previous study showed a dramatic drop of mechanical property of DD6 bicrystalline slabs when the misorientation angle increased to about 10°.…”

Section: Discussionmentioning

confidence: 95%

Misorientation related microstructure at the grain boundary in a nickel-based single crystal superalloy

Huang

Zhuo

Liu

et al. 2015

Materials Science and Engineering: A

Self Cite

View full text Add to dashboard Cite

Coupling between Re segregation and γ/γ′ interfacial dislocations during high-temperature, low-stress creep of a nickel-based single-crystal superalloy

Cited by 105 publications

References 23 publications

On the segregation of Re at dislocations in the γ' phase of Ni-based single crystal superalloys

On the segregation of Re at dislocations in the γ' phase of Ni-based single crystal superalloys

Influence of Heat Treatment on Defect Structures in Single-Crystalline Blade Roots Studied by X-ray Topography and Positron Annihilation Lifetime Spectroscopy

Misorientation related microstructure at the grain boundary in a nickel-based single crystal superalloy

Contact Info

Product

Resources

About