Oxidation of high-temperature alloys (superalloys) at elevated temperatures in air. II

Hussain, Nazar; Shahid, K. A.; Khan, Iqra Haider; Rahman, S.

doi:10.1007/bf01047036

Cited by 49 publications

(21 citation statements)

References 10 publications

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“…Therefore, the oxidation kinetic of IN 718 changed as oxidation progressed; at the early stage, the rapid formation of MnCr 2 O 4 occurred which decreased inward diffusion of oxygen and suppressed the oxidation process of Cr ions. Additionally, previous studies [52,53], pointed out that Mn 1.5 Cr 1.5 O 4 located at the external interface, could reduce the conversion of Cr 2 O 3 into a CrO 3 volatile oxide above 900°C. Other authors indicated that Mn 1.5 Cr 1.5 O 4 is non-protective because it presents a porous structure [54,55].…”

Section: Discussionmentioning

confidence: 97%

Cyclic Oxidation Behavior of IN 718 Superalloy in Air at High Temperatures

et al. 2010

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Ni-base superalloy IN 718 was cyclically oxidized in laboratory air at temperatures ranging from 750 to 950°C for up to 12 cycles (14 h/cycle). The kinetic behaviour as well as the surface morphology, and the oxide phases of the scales were characterized by means of weight gain measurements, cyclic oxidation kinetics, scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS), and X-ray diffraction (XRD) analysis techniques. The results showed that as the oxidation temperature increased, the oxidation rate, the external scale thickness, and internal oxidation zone increased. It was suggested that the oxidation rate was controlled by the diffusion of substrate elements in the alloy and the inward diffusion of oxygen through the oxide scale. The oxidation kinetics followed a sub-parabolic rate law and, the activation energy of oxidation was 249 ± 20 kJ mol -1 . The scaling process was controlled mainly by the diffusion of chromium, titanium, manganese, and oxygen ions through the chromia scale. IN 718 showed low weight gain and very slow reaction rates of substrate elements at 750°C. At 850°C, a continuous and very thin oxide scale was formed. At 950°C, XRD and EDS-elemental mapping analysis revealed that a complex oxide scale had formed. It consisted of an outermost layer of TiO 2 -MnCr 2 O 4 spinels, inner layer of Cr 2 O 3 , and the inner most layer composed of Ni 3 Nb enriched with Nb, Ti and Al oxides underneath the chromia layer. The oxide scale at this temperature seemed to be thicker layer, significant spallation and volatilization had apparently occurred, and greater internal corrosion was identified. The doping effect of titanium was observed, where it was found to be diffused through the chromia scale to form TiO 2 at the oxide-gas interface as well as internally and at the oxide alloy interface.

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Section: Discussionmentioning

confidence: 97%

Cyclic Oxidation Behavior of IN 718 Superalloy in Air at High Temperatures

et al. 2010

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“…Parabolic kinetics have been reported in several studies on alloys of similar compositions that were subjected to similar oxidizing temperatures [1][2][3]6]. Thus, parabolic oxidation kinetics were assumed for the alloys employed in this study as well.…”

Section: Oxidation Experiments and Sample Informationmentioning

confidence: 98%

“…Many elevated-temperature engineering components for nuclear reactors, electricalresistance heaters, and gas-turbine engines are made of nickel-based superalloys [1][2][3][4][5]. Nickel-based superalloys are employed in these applications due to their corrosion-resistance and mechanical properties at elevated temperatures [5].…”

Section: Introductionmentioning

confidence: 99%

An Evaluation of the Use of X-ray Residual Stress Determination as a Means of Characterizing Oxidation Damage of Nickel-Based, Cr2O3-Forming Superalloys Subjected to Various Oxidizing Conditions

2010

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The use of X-ray residual stress determination as a technique for evaluating the damage incurred by nickel-based, Cr 2 O 3 -forming superalloy materials under various service conditions (isothermal heating, thermal cycling, applied stress, stressed and cycled) was investigated. Large and small compressive residual stresses were observed for the oxides and the near surface substrates, respectively. It was expected that the applied stresses and thermal cycling would cause an enhanced degree of oxidation damage that would translate into appreciable differences in residual stress values. Differences in the magnitude of residual stress values were not appreciable condition-to-condition, however. An increase in the severity of the oxidizing conditions in the form of longer oxidation times, higher oxidizing temperatures, and a much greater frequency of thermal cycling is suggested for future studies.

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“…Other authors pointed out that Mn 1.5 Cr 1.5 O 4 located at the external interface, could reduce the conversion of Cr 2 O 3 into a CrO 3 volatile oxide above 900 8C [29][30][31]. Some authors indicated that Mn 1.5 Cr 1.5 O 4 is nonprotective because it presents a porous structure [32,33]. Nevertheless, if manganese oxides crack at the external interface it does not affect the adherent protective chromia scale [34].…”

Section: Manganese Influencementioning

confidence: 99%

330Cb alloy (Fe35Ni18Cr1Nb2Si) oxidation study between 800 and 1000 °C

Issartel¹,

Buscail²,

Nguyen³

et al. 2010

Materials & Corrosion

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The 330Cb alloy (Fe-35Ni-18Cr-1Nb-2Si) has been oxidized, in air, in the 800-1000 8C temperature range. Results show the formation of a chromia layer acting as a good diffusion barrier under isothermal conditions. Nevertheless, some oxide scale spallation is generally observed after cooling to room temperature. A fine and adherent chromia scale is only obtained after short-term oxidation at 800 8C. In this case, the scale is probably too fine to expect a protection against carburization. At 900 8C we have observed that the scale spalled off on the niobium rich alloy areas. At 1000 8C the scale adherence is very bad. This study shows that the oxide scale adherence is decreased when the 330Cb alloy oxidation duration is increased.

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Oxidation of high-temperature alloys (superalloys) at elevated temperatures in air. II

Cited by 49 publications

References 10 publications

Cyclic Oxidation Behavior of IN 718 Superalloy in Air at High Temperatures

Cyclic Oxidation Behavior of IN 718 Superalloy in Air at High Temperatures

An Evaluation of the Use of X-ray Residual Stress Determination as a Means of Characterizing Oxidation Damage of Nickel-Based, Cr2O3-Forming Superalloys Subjected to Various Oxidizing Conditions

330Cb alloy (Fe35Ni18Cr1Nb2Si) oxidation study between 800 and 1000 °C

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