Influences of chromium and hafnium additions on the microstructures of β-nial coatings on superalloy substrates

Bestor, Michael A; Alfano, Joel; Weaver, M.L.

doi:10.1016/j.intermet.2011.06.020

Cited by 18 publications

(9 citation statements)

References 79 publications

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“…It can be inferred from Figs. 7 and 8 that, during the cyclic oxidation, Si in the NiAl coating diffuses toward the substrate and is enriched in the substrate, which is consistent with our first-principle calculation results that the solubility of Si in c 0 -Ni 3 Al is significantly higher than that in b-NiAl [18]. As the enrichment of Si contributes to stabilizing b-NiAl and a-Cr phases, the addition of Si to the NiAlHfCr coating has a beneficial effect on oxide scale adherence.…”

Section: Cyclic Oxidation Of Cr-/si-doped Nialhf Coatingssupporting

confidence: 88%

“…This implies that Si doping contributes to grain refinement. In our previous work, Si segregated at the grain boundaries of the NiAl coating, thus suppressing the grain growth of the coating [18]. Figure 2 shows the SEM images of cross sections of the NiAlHfCr (Fig.…”

Section: Microstructures Of Cr-/si-modified Nialhf Coatingsmentioning

confidence: 92%

“…The benefit of Hf, however, is limited when the coatings are exposed to hot-corrosion environment. The effect mechanisms of Cr on the hot-corrosion and high-temperature oxidation resistance of NiAl coatings were discussed [15][16][17][18][19]. The addition of Cr effectively improves the hot-corrosion resistance of NiAl but degrades the oxidation resistance [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

“…The effect mechanisms of Cr on the hot-corrosion and high-temperature oxidation resistance of NiAl coatings were discussed [15][16][17][18][19]. The addition of Cr effectively improves the hot-corrosion resistance of NiAl but degrades the oxidation resistance [17][18][19]. One of possible reasons may be that the addition of Cr increases the amount of sulfur, which may compromise the beneficial role of REs, particularly because RE content is usually extremely low [19].…”

Section: Introductionmentioning

confidence: 99%

“…One of possible reasons may be that the addition of Cr increases the amount of sulfur, which may compromise the beneficial role of REs, particularly because RE content is usually extremely low [19]. Also, volatilization of CrO 3 occurs during high-temperature oxidation, related to spallation of oxide scale [17,18]. In our previous work, Si and Cr can form a compound of Cr 5 Si 3 , which effectively suppresses the gathering of Cr [17].…”

Section: Introductionmentioning

confidence: 99%

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Cyclic oxidation behavior of Cr-/Si-modified NiAlHf coatings on single-crystal superalloy produced by EB-PVD

et al. 2015

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The Cr-/Si-modified NiAlHf coatings were produced on single-crystal (SC) superalloy N5 by electron beam physical vapor deposition (EB-PVD). The cyclic oxidation behavior of the coatings at 1100°C was investigated. The microstructures of the oxide scales grown on the coatings were characterized by scanning electron microscope (SEM) with energy-dispersive X-ray spectrum (EDX), electron probe micro-analyzer (EPMA) and X-ray diffraction (XRD). The effects of Cr and Si on the cyclic oxidation behavior of the NiAlHf coatings were discussed. The addition of Si to the NiAlHfCr coating not only reduces the oxidation rate but also enhances the oxide scale adherence.Owing to the addition of Si in the coating, the segregation of Cr and Mo beneath the oxide scale is effectively avoided, which contributes to enhancing oxide scale adherence.

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Section: Cyclic Oxidation Of Cr-/si-doped Nialhf Coatingssupporting

confidence: 88%

Section: Microstructures Of Cr-/si-modified Nialhf Coatingsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Cyclic oxidation behavior of Cr-/Si-modified NiAlHf coatings on single-crystal superalloy produced by EB-PVD

et al. 2015

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The oxidation behaviour of the pulse plasma sintered β‐NiAl intermetallic compound under thermal cycling conditions at 1150 °C

Jedliński

Dąbek

Prażuch

et al. 2016

Materials & Corrosion

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The effect of microstructure engineering using a new manufacturing route (pulse plasma sintering (PPS)) on the high temperature oxidation behaviour of β‐NiAl coating material with and without small amounts of Hf was determined at 1150 °C under thermal cycling conditions in air. Vacuum melted β‐NiAl compounds with and without Hf were used as reference materials and tested under the same conditions. The oxide scales were observed using SEM and analysed using EDX. The results showed that the Hf‐containing materials behaved better than Hf‐free ones and among the Hf‐containing materials, the vacuum melted one exhibited significantly better cyclic oxidation resistance than the PPS material. Thus, no improvement of the oxidation resistance was achieved using the applied manufacturing procedure. The scales prone to spallation were at considerably later stages of the scale evolution and less intact with the substrate than the scale resistant to spallation.

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Comparison of Isothermal with Cyclic Oxidation Behavior of “Cr-Aluminide” Coating on Inconel 738LC at 900 °C

et al. 2016

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Influences of chromium and hafnium additions on the microstructures of β-nial coatings on superalloy substrates

Cited by 18 publications

References 79 publications

Cyclic oxidation behavior of Cr-/Si-modified NiAlHf coatings on single-crystal superalloy produced by EB-PVD

Cyclic oxidation behavior of Cr-/Si-modified NiAlHf coatings on single-crystal superalloy produced by EB-PVD

The oxidation behaviour of the pulse plasma sintered β‐NiAl intermetallic compound under thermal cycling conditions at 1150 °C

Comparison of Isothermal with Cyclic Oxidation Behavior of “Cr-Aluminide” Coating on Inconel 738LC at 900 °C

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