High-temperature oxidation behaviour of minor Hf-doped β-NiAl single crystals in dry and humid atmospheres

Yan, Kai; He, Jian; Guo, Hongbo

doi:10.1007/s12598-018-1095-x

Cited by 5 publications

(3 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, the distribution of HfO 2 varied with the different environments and heating methods. In an air atmosphere, stepped heating accelerated the segregation of Hf in the oxide scale and the formation of oxides with O [27]. A portion of singlet Hf also diffused into the alloy along the grain boundaries and increased the bond strength of the oxide scale.…”

Section: Effects Of Heating Methods and Atmosphere On The Morphologie...mentioning

confidence: 99%

Effects of Stepped Heating on the Initial Growth of Oxide Scales on NiCrAlHf Bond Coat Alloy under Air and Water Vapor Atmospheres

Zheng

Song

et al. 2022

Materials

View full text Add to dashboard Cite

Temperature and atmosphere have a significant effect on the oxidation of MCrAlY (M = Ni, Co) bond coating. The initial growth behavior of the NiCrAlHf bond coat alloy was investigated at 1100 °C under different atmospheric conditions and using heating methods. A thick Al2O3 oxide layer and large HfO2 particles were observed, perhaps due to metastable oxide growth at low temperatures when using stepped heating. However, in air and water vapor atmospheres, the oxide scale was thinner and the HfO2 precipitates were smaller in stepped heating than in constant heating. The size and distribution of the HfO2 particles might have induced different microstructures, particularly voids within the oxide scale.

show abstract

Section: Effects Of Heating Methods and Atmosphere On The Morphologie...mentioning

confidence: 99%

Effects of Stepped Heating on the Initial Growth of Oxide Scales on NiCrAlHf Bond Coat Alloy under Air and Water Vapor Atmospheres

Zheng

Song

et al. 2022

Materials

View full text Add to dashboard Cite

show abstract

“…-25Cr-0.4C-6M with M = 2/3 Ta and 1/3 Hf for one alloy (named "T alloy") or M = 2/3 Hf and 1/3 Ta for the second alloy (named "H alloy"). This supposes the introduction of hafnium with unusually high concentrations (2 and 4 wt.% Hf), compared to other Ni-based superalloys [12,13], nickel aluminides [14], single crystals [15], Nb-based refractory alloys [16,17] or HEAs (High Entropy Alloys) [18][19][20].…”

Section: Design Of the Alloysmentioning

confidence: 99%

Oxidation and Microstructural Behaviors of Ni-Based Alloys Strengthened by (Ta, Hf)C Carbides at 1250 °C in Air

2021

View full text Add to dashboard Cite

Two alloys based on nickel and designed to be reinforced by MC carbides thanks to the presence of Hf and Ta were produced by casting. They were subjected to 50 h-long isothermal exposure at 1250 °C in synthetic air with thermogravimetric monitoring of the oxidation progress. In the as-cast state, they contain both significant quantities of (Hf,Ta)C carbides. Their verified melting start temperatures, close to 1300 °C, allowed performing the planned oxidation test. The two alloys demonstrated a chromia-forming behavior with limited mass gain rates. However, they also showed a rather low resistance to oxide spallation at cooling, which is in proportion with the Ta/Hf ratio. After 50 h at 1250 °C, the morphology of the carbides had significantly evolved, from their initial script-like shape to a fragmented and coalesced state. The results are promising, but the use of these alloys at 1250 °C needs further improvements on the mechanical level.

show abstract

“…Hafnium is first known to significantly influence the oxidation behavior of high temperature oxidation of refractory materials of various types, ceramic as well as metallic [1][2][3]. For this reason, Hf is therefore added in some Nb-based alloys [4][5][6], Co-based alloys [7], Nialloys [8] or nickel aluminides [9][10].…”

Section: Introductionmentioning

confidence: 99%

Oxidation of a 2wt.%Hf–doped (Ta,C)-rich nickel–based alloy between 1100 and 1250°C

2022

View full text Add to dashboard Cite

In this work, an alloy based on nickel, rich in chromium and designed to be reinforced by MC carbides thanks to the presence of 4wt.% Ta and 2wt.% Hf, was elaborated by conventional casting and exposed to air at three temperatures ranging from 1100 to 1250°C, with follow up of the mass changes due to oxidation. The as–cast microstructure is composed of a dendritic matrix and of eutectic carbides of two types. The major type is (Ta,Hf)C carbide and a minor type is chromium carbide. The isothermal mass gains are slow and their kinetics are of a parabolic type at all temperatures. The alloy demonstrated a chromia–forming behavior in all cases, with the development of an external continuous chromia scale and an internal layer of complex oxide Cr(Ta,Hf)O4. The stability of the external scale during cooling was dependent on the quantity of oxides isothermally formed, i.e. on the oxidation temperature for a given duration. The behavior of the alloy in isothermal oxidation at the considered temperatures is satisfactory but solutions must be found for improving the resistance against cyclic oxidation for the highest temperatures.

show abstract

High-temperature oxidation behaviour of minor Hf-doped β-NiAl single crystals in dry and humid atmospheres

Cited by 5 publications

References 32 publications

Effects of Stepped Heating on the Initial Growth of Oxide Scales on NiCrAlHf Bond Coat Alloy under Air and Water Vapor Atmospheres

Effects of Stepped Heating on the Initial Growth of Oxide Scales on NiCrAlHf Bond Coat Alloy under Air and Water Vapor Atmospheres

Oxidation and Microstructural Behaviors of Ni-Based Alloys Strengthened by (Ta, Hf)C Carbides at 1250 °C in Air

Oxidation of a 2wt.%Hf–doped (Ta,C)-rich nickel–based alloy between 1100 and 1250°C

Contact Info

Product

Resources

About