Microstructural modelling solution for complex Co based alloys and coatings

Salam, S.; Hou, P.Y.; Zhang, Y.-D.; Zhang, X.-H.; Wang, H.-F.; Zhang, C.; Yang, Zhigang

doi:10.1016/j.surfcoat.2013.10.059

Cited by 6 publications

(5 citation statements)

References 21 publications

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“…Koßmann et al [12] studied micro-segregation and the precipitates of as-cast Co-Al-W superalloys from the TCNI5 database, but they found limited applicability of results from the thermodynamical calculations to their experimental results. Contrarily, an excellent agreement with the experimental results was given in a study on Co-Ni-Cr-Al-Re-Y alloys by Salam et al [13], although their compositions included Ni up to 31.5 wt. %.…”

Section: Introductionsupporting

confidence: 71%

“…In the current work, we performed thermodynamic equilibrium calculations using the Thermo-Calc software 2016a (Thermo-Calc Software AB, Solna, Sweden). Similar compositions of cobalt-based alloys [9][10][11][12][13] were calculated using databases developed for both steels and nickel-based superalloys. Therefore, the calculations were performed using the thermodynamic databases TCFE8 and TCNI8.…”

Section: Thermodynamic Calculationsmentioning

confidence: 99%

“…The Thermo-Calc software (TCS) [8] coupled with thermodynamic databases is widely used for calculations related to cobalt-based alloys. Recent studies [9][10][11][12][13] have employed databases for steel and nickel alloys. The current version is the TCS Steels/Fe-alloys Database Version 8 (TCFE8) [14], where the recommended composition limit for Co in this database is lower than 20 (wt.…”

Section: Introductionmentioning

confidence: 99%

“…They calculated the FCC and HCP phases, as well as the Sigma phase, owing to the lack of carbon in the composition. On the other hand, the Ni-based superalloys database was used for the Co based alloys [12,13]. Koßmann et al [12] studied micro-segregation and the precipitates of as-cast Co-Al-W superalloys from the TCNI5 database, but they found limited applicability of results from the thermodynamical calculations to their experimental results.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the Aging Effect on the Microstructure of Co-28Cr-6Mo-0.3C Alloy: Experimental Characterization and Computational Thermodynamics

Zangeneh

Erişir

Abbasi

et al. 2019

Metals

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In the current research, we studied the role of the solution treatment and aging on the microstructure of a Co–28Cr–5Mo–0.3C alloy. We used metallographic observations, scanning electron microscopy (SEM), and hardness measurements for the evaluations. We also made a comparison between the phase equilibrium calculated with Thermo-Calc, using TCFE8 and TCNI8 thermodynamic databases and experimental findings. The experimental results showed that the transformation of the metastable FCC phase to the HCP phase during aging was extremely sensitive to the solution treatment prior to aging. The effect of the increase in the solution temperature and time was detectable through promotion of the martensitic transformation during quenching in which HCP1 (straight bands) and HCP2 (lamellar-type constitution) phases had developed. In contrast, a low solution temperature and time caused most of the primary carbides to remain in an undissolved condition in the matrix; therefore, during aging, no sign of the FCC to HCP1 (straight bands) phase transformation could be observed. However, we observed the formation of the HCP2 phase (lamellar-type constitution) at the grain boundaries. In addition, the X-ray diffraction pattern indicated that the sample solution treated at lower temperatures and shorter times had a stronger martensitic transformation during aging compared to the sample solution treated at higher temperatures and longer times. Hardness measurements confirmed the results. Thermodynamical calculations showed that an agreement existed between the experiments and calculations. We also discuss the results from the TCFE8 and TCNI8 databases.

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Section: Introductionsupporting

confidence: 71%

Section: Thermodynamic Calculationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluation of the Aging Effect on the Microstructure of Co-28Cr-6Mo-0.3C Alloy: Experimental Characterization and Computational Thermodynamics

Zangeneh

Erişir

Abbasi

et al. 2019

Metals

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“…This mismatch explains the formation of tensile cracks in the coating. Moreover, the greater the Al content, the harder the intermetallic phase but the more brittle they become [7,10]. Therefore, the cracks are often blunted at the interface between the additive layer (Al-rich) and the interdiffusion zone where the Al and Fe contents are equivalent or are even Fe-rich.…”

Section: Introductionmentioning

confidence: 99%

Suitable sealants for cracked aluminized austenitic steels and their oxidation behaviour

Boulesteix

Pedraza

2017

Surface and Coatings Technology

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Aluminizing of steels may result in the appearance of tensile cracks from the coating surface to the substrate due to the difference in thermal expansion coefficients. The cracks often need to be sealed to make the coatings impervious to chemical attack and to limit their mechanical degradation. In this work, dipping of the cracked aluminide coatings elaborated on IN-800HT in 0.5, 1 and 3.75 mol.L-1 concentrations of H3PO4 in acetone and increasing the dipping time are investigated. The three concentrations resulted in the formation of P-O compounds and of Al2O3. However, the 0.5 mol.L-1 allowed better wetting of the surface. Further reduction of the concentration from 0.5 mol.L-1 to 0.2 mol.L-1 brought about the complete sealing of both large and fine cracks. The efficiency of the sealing process with 0.2 mol.L-1 and 0.5 mol.L-1 was thereafter evaluated by cyclic oxidation in air at 650°C for more than 1000 cycles. The overall microstructure and composition of the aluminide coatings remained identical after sealing and the oxidation behaviour comparable to the untreated counterparts. The oxide scale formed on the untreated samples appeared thicker compared to the sealed ones. The latter were covered by a thin layer of AlPO4 which evolved towards a thin protective alumina scale. However, for the sealed samples, some minor cracks were detected after oxidation but they appeared completely healed with Al2O3 and no propagation of them beyond the additive layer/interdiffusion zone was noticed.

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Interdiffusion in the Face-Centered Cubic Phase of the Co-Al-W-Ta System Between 1090 and 1240 °C

Epishin

Chyrkin

Nolze

et al. 2018

J. Phase Equilib. Diffus.

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Microstructural modelling solution for complex Co based alloys and coatings

Cited by 6 publications

References 21 publications

Evaluation of the Aging Effect on the Microstructure of Co-28Cr-6Mo-0.3C Alloy: Experimental Characterization and Computational Thermodynamics

Evaluation of the Aging Effect on the Microstructure of Co-28Cr-6Mo-0.3C Alloy: Experimental Characterization and Computational Thermodynamics

Suitable sealants for cracked aluminized austenitic steels and their oxidation behaviour

Interdiffusion in the Face-Centered Cubic Phase of the Co-Al-W-Ta System Between 1090 and 1240 °C

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