Effect of Chromium Content on the Oxidation Behavior of a Ta Stabilized γ’-Strengthened Polycrystalline Co-30Ni-10Al-4W-4Ti-2Ta Alloy

The high-temperature oxidation behaviors of polycrystalline Co-30Ni-10Al-4W-4Ti-2Ta superalloys with Cr contents ranging from 1 to 5 at.% are characterized at 900 °C to provide benchmark data for the alloy design of the CoNi-based superalloys. The mass gain curves for all three alloys exhibit parabo...

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Main Authors: Kun Qian, Shasha Qu, Lei Shu, Peng Xue, Xiaobing Li, Bo Chen, Kui Liu
Format: Article
Language:English
Published: MDPI AG 2022-08-01
Series:Materials
Subjects:
Online Access:https://www.mdpi.com/1996-1944/15/17/5833
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author Kun Qian
Shasha Qu
Lei Shu
Peng Xue
Xiaobing Li
Bo Chen
Kui Liu
author_facet Kun Qian
Shasha Qu
Lei Shu
Peng Xue
Xiaobing Li
Bo Chen
Kui Liu
author_sort Kun Qian
collection DOAJ
description The high-temperature oxidation behaviors of polycrystalline Co-30Ni-10Al-4W-4Ti-2Ta superalloys with Cr contents ranging from 1 to 5 at.% are characterized at 900 °C to provide benchmark data for the alloy design of the CoNi-based superalloys. The mass gain curves for all three alloys exhibit parabolic growth, and the addition of 5Cr at.% is sufficient to decrease the oxidation rate by two orders of magnitude compared to the Cr-free alloy. Furthermore, cross-sectional findings reveal that these three alloys form qualitatively similar oxide scales composed of an outer oxide layer of Co<sub>3</sub>O<sub>4</sub> and CoAl<sub>2</sub>O<sub>4</sub> phase on top of an Al<sub>2</sub>O<sub>3</sub> scale, following the inner oxide layers of Cr<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub>, and TiTaO<sub>4</sub>, and internally oxidized Al<sub>2</sub>O<sub>3</sub> precipitate. The alloy forms a chromium-rich oxide scale as the Cr addition increased, and the concentration of Cr in the scale/alloy interface increases, promoting the growth of Cr<sub>2</sub>O<sub>3</sub>, while CoAl<sub>2</sub>O<sub>4</sub> and Co<sub>3</sub>O<sub>4</sub> nucleation is inhibited. The results further indicate that Cr has a superior effect on improving the oxidation resistance of CoNi-based alloys and that a higher content of Cr can assist the formation of a continuous Al<sub>2</sub>O<sub>3</sub>, Cr<sub>2</sub>O<sub>3</sub>, and TiTaO<sub>4</sub> layers, which in turn hampers outer Co and Ni, and inward oxygen flux.
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spelling doaj.art-c347544b3da742538d3262af133e05312023-11-23T13:30:58ZengMDPI AGMaterials1996-19442022-08-011517583310.3390/ma15175833Effect of Chromium Content on the Oxidation Behavior of a Ta Stabilized γ’-Strengthened Polycrystalline Co-30Ni-10Al-4W-4Ti-2Ta AlloyKun Qian0Shasha Qu1Lei Shu2Peng Xue3Xiaobing Li4Bo Chen5Kui Liu6Jihua Laboratory, Foshan 528200, ChinaGuangdong Institute of Special Equipment Inspection and Research, Guangzhou 510620, ChinaJihua Laboratory, Foshan 528200, ChinaJihua Laboratory, Foshan 528200, ChinaJihua Laboratory, Foshan 528200, ChinaJihua Laboratory, Foshan 528200, ChinaJihua Laboratory, Foshan 528200, ChinaThe high-temperature oxidation behaviors of polycrystalline Co-30Ni-10Al-4W-4Ti-2Ta superalloys with Cr contents ranging from 1 to 5 at.% are characterized at 900 °C to provide benchmark data for the alloy design of the CoNi-based superalloys. The mass gain curves for all three alloys exhibit parabolic growth, and the addition of 5Cr at.% is sufficient to decrease the oxidation rate by two orders of magnitude compared to the Cr-free alloy. Furthermore, cross-sectional findings reveal that these three alloys form qualitatively similar oxide scales composed of an outer oxide layer of Co<sub>3</sub>O<sub>4</sub> and CoAl<sub>2</sub>O<sub>4</sub> phase on top of an Al<sub>2</sub>O<sub>3</sub> scale, following the inner oxide layers of Cr<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub>, and TiTaO<sub>4</sub>, and internally oxidized Al<sub>2</sub>O<sub>3</sub> precipitate. The alloy forms a chromium-rich oxide scale as the Cr addition increased, and the concentration of Cr in the scale/alloy interface increases, promoting the growth of Cr<sub>2</sub>O<sub>3</sub>, while CoAl<sub>2</sub>O<sub>4</sub> and Co<sub>3</sub>O<sub>4</sub> nucleation is inhibited. The results further indicate that Cr has a superior effect on improving the oxidation resistance of CoNi-based alloys and that a higher content of Cr can assist the formation of a continuous Al<sub>2</sub>O<sub>3</sub>, Cr<sub>2</sub>O<sub>3</sub>, and TiTaO<sub>4</sub> layers, which in turn hampers outer Co and Ni, and inward oxygen flux.https://www.mdpi.com/1996-1944/15/17/5833CoNi-based superalloysoxidation behaviorsparabolic growth
spellingShingle Kun Qian
Shasha Qu
Lei Shu
Peng Xue
Xiaobing Li
Bo Chen
Kui Liu
Effect of Chromium Content on the Oxidation Behavior of a Ta Stabilized γ’-Strengthened Polycrystalline Co-30Ni-10Al-4W-4Ti-2Ta Alloy
Materials
CoNi-based superalloys
oxidation behaviors
parabolic growth
title Effect of Chromium Content on the Oxidation Behavior of a Ta Stabilized γ’-Strengthened Polycrystalline Co-30Ni-10Al-4W-4Ti-2Ta Alloy
title_full Effect of Chromium Content on the Oxidation Behavior of a Ta Stabilized γ’-Strengthened Polycrystalline Co-30Ni-10Al-4W-4Ti-2Ta Alloy
title_fullStr Effect of Chromium Content on the Oxidation Behavior of a Ta Stabilized γ’-Strengthened Polycrystalline Co-30Ni-10Al-4W-4Ti-2Ta Alloy
title_full_unstemmed Effect of Chromium Content on the Oxidation Behavior of a Ta Stabilized γ’-Strengthened Polycrystalline Co-30Ni-10Al-4W-4Ti-2Ta Alloy
title_short Effect of Chromium Content on the Oxidation Behavior of a Ta Stabilized γ’-Strengthened Polycrystalline Co-30Ni-10Al-4W-4Ti-2Ta Alloy
title_sort effect of chromium content on the oxidation behavior of a ta stabilized γ strengthened polycrystalline co 30ni 10al 4w 4ti 2ta alloy
topic CoNi-based superalloys
oxidation behaviors
parabolic growth
url https://www.mdpi.com/1996-1944/15/17/5833
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