Effect of boron additions on the microstructure and transverse properties of a directionally solidified superalloy

Yan, B.C.; Zhang, J.; Lou, Langhong

doi:10.1016/j.msea.2007.05.082

Cited by 93 publications

(26 citation statements)

References 18 publications

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“…Because boron is not dissolved in the g matrix, the studies are mainly focused on the segregation of boron at grain boundaries [8e13] and grain boundary strengthening mechanism of polycrystalline alloys [14e20]. The main strengthening mechanisms has been outlined as followings, (1) increased boundary interfacial strength [7,21,22], (2) decreased grain boundary diffusivity [7], (3) modification of the morphology of fine g 0 or carbides [7,23], and (4) delaying the selective segregation of S at voids [24].…”

Section: Introductionmentioning

confidence: 99%

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The role of boron in modifying the solidification and microstructure of nickel-base alloy U720Li

Zhao

Yang

et al. 2016

Journal of Alloys and Compounds

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Section: Introductionmentioning

confidence: 99%

“…However, boron also has some harmful effects, for example, boron addition promotes the formation of eutectic (g þ g 0 ) [21,25], which is unfavorable for the homogenization process [26]. U720Li alloy has a high tendency to form the eutectic (g þ g 0 ), because the total amount of (Al þ Ti) is as high as 7.5 wt%.…”

Section: Introductionmentioning

confidence: 99%

The role of boron in modifying the solidification and microstructure of nickel-base alloy U720Li

Zhao

Yang

et al. 2016

Journal of Alloys and Compounds

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“…[1,[8][9][10][11] In particular, the latter is known to have a detrimental effect on high-temperature creep resistance. For example, Yan et al [12] reported that the eutectic region, specifically the interface between c/c¢ eutectic and matrix, is the most preferential crack initiation site during creep rupture. In addition, Murakumo et al [13] suggested that complete dissolution of coarse eutectic regions would be effective for creep strengthening of the single-crystal (SX) Ni-base superalloy TMS-75 at 1173 K (900°C).…”

Section: Introductionmentioning

confidence: 99%

A Comparative Study of the γ/γ′ Eutectic Evolution During the Solidification of Ni-Base Superalloys

Seo

Lee

Yoo

et al. 2011

Metall Mater Trans A

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The evolution of c/c¢ eutectic during the solidification of Ni-base superalloys CMSX-10 and CMSX-4 was investigated over a wide range of cooling rates. The microsegregation behavior during solidification was also quantitatively examined to clarify the influence of elemental segregation on the evolution of c/c¢ eutectic. In the cooling rate ranges investigated (0.9 to 138.4 K/min (0.9 to 138.4°C/min)), the c/c¢ eutectic fraction in CMSX-10 was found to be more than 2 times higher than that in CMSX-4 at a given cooling rate. However, the dependence of the c/c¢ eutectic fraction on the cooling rate in both alloys showed a similar tendency; i.e., the c/c¢ eutectic fraction increased with increasing the cooling rate and then exhibited a maximum plateau at and above the certain critical cooling rate in both alloys. This critical cooling rate was found to be dependent on the alloy composition and was estimated to be about 12 K/min (12°C/min) and 25 K/min (25°C/min) for CMSX-10 and CMSX-4, respectively. The calculated solid compositions based on the modified Scheil model revealed that even a small compositional difference of total c¢ forming elements in the initial composition of the alloy can play a significant role in the as-cast eutectic fraction during the solidification of Ni-base superalloys. The evolution of the c/c¢ eutectic fraction with respect to the cooling rate could be rationalized by taking into account the effects of back-diffusion in solid and dendrite arm coarsening on decreasing the extent of microsegregation.

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“…The detectors were aligned to detect the ion species 12 O − signals because it gives a highest signal intensity [9]. Image processing was carried out using ImageJ software (U.S. National Institutes of Health, Bethesda, MD) using the OpenMIMS plugin (National Resource for Imaging Mass Spectometry, Harvard University, Cambridge, MA).…”

Section: Segregation Of Carbon and Boronmentioning

confidence: 99%

“…As a consequence higher amounts of boron diffuse from the γ matrix towards the growing M 23 C 6 carbide [11]. Yan [12] has suggested that the segregation of boron to the grain boundaries can facilitate the formation of γ layers along the grain boundaries, in terms of interface energy. The presence of boron in the M 23 C 6 results in the increase of the lattice misfit of M 23 C 6 /γ and M 23 C 6 /γ interfaces.…”

Section: The Formation Of γ Layersmentioning

confidence: 99%

On the effect of boron on the mechanical properties of a new polycrystalline superalloy

Kontis

Yusof

Moore

et al. 2014

MATEC Web of Conferences

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Abstract. Boron is used as a grain boundary strengthener in the nickel-based superalloys, but the reasons for its effect and the optimum quantities which need to be added are not well understood. Recently, some of the authors have developed a new corrosion-resistant single crystal superalloy for power generation applications which has a good balance of mechanical properties and resistance to environmental degradation. Here, this same alloy system is studied but in the polycrystalline state with additions of boron and carbon. The influence of boron on creep behaviour has been quantified and rationalised, with an emphasis on the grain boundary phase transformations which occur. NanoSIMS is utilised to investigate the segregation of boron at grain boundaries, with SEM used to characterise the effect of boron on the precipitation of Cr 23 C 6 type carbides at grain boundaries. When the boron content increases, the agglomeration of M 23 C 6 carbides at grain boundaries is inhibited. Uniformly distributed discrete M 23 C 6 carbides are observed at higher boron content, whereas a deleterious film of M 23 C 6 along the grain boundaries arises as the boron concentration is reduced. Boron promotes also the formation of γ layers at the grain boundaries.

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Effect of boron additions on the microstructure and transverse properties of a directionally solidified superalloy

Cited by 93 publications

References 18 publications

The role of boron in modifying the solidification and microstructure of nickel-base alloy U720Li

The role of boron in modifying the solidification and microstructure of nickel-base alloy U720Li

A Comparative Study of the γ/γ′ Eutectic Evolution During the Solidification of Ni-Base Superalloys

On the effect of boron on the mechanical properties of a new polycrystalline superalloy

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