Native oxidation resistance of Al20Nb30Ta10Ti30Zr10 refractory complex concentrated alloy (RCCA)

The native oxidation resistance of an Al20Nb30Ta10Ti30Zr10 (at.%) refractory complex concentrated alloy (RCCA) was evaluated at 1000 °C in air. Oxidation tests revealed that the alloy exhibits linear oxidation kinetics out to 4 h of oxidation, with an adherence to parabolic, diffusion-controlled oxi...

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Bibliographic Details
Published in:Journal of alloys and compounds 2019-05, Vol.787, p.606-617
Main Authors: Butler, T.M., Chaput, K.J.
Format: Article
Language:English
Subjects:
Alloys
Complex concentrated alloys
High-entropy
Oxidation
Oxidation resistance
Oxidation tests
RCCA
Reaction kinetics
Refractory
Refractory alloys
Refractory materials
Scale (corrosion)
Titanium dioxide
Zirconium dioxide
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Summary:The native oxidation resistance of an Al20Nb30Ta10Ti30Zr10 (at.%) refractory complex concentrated alloy (RCCA) was evaluated at 1000 °C in air. Oxidation tests revealed that the alloy exhibits linear oxidation kinetics out to 4 h of oxidation, with an adherence to parabolic, diffusion-controlled oxidation from 4 to 100 h. This transition was ultimately attributed to the formation of an outer oxide consisting primarily of TiO2 and Ti7Al2O15 layers. The 100 h oxide product contained multiple internal layers, but the overall oxidation kinetics was proposed to be controlled by the outer composite oxide layer. While this layer was morphologically continuous, it consisted of a non-continuous mixture of NbAlO4, ZrO2, Ti7Al2O15, and Ta2Nb4O15. The observed oxide scales are discussed relative to the oxidation behaviors of less-complex alloys. [Display omitted] •AlNb1.5Ta0.5Ti1.5Zr0.5 exhibits moderate oxidation kinetics in air at 1000 °C out to 100 h.•The resistance was due to a composite mixture of NbAlO4, ZrO2, Ti7Al2O15, and Ta2Nb4O15.•RCCAs exhibit a range of complex oxides not readily accessible to dilute refractory alloys.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2019.02.128