{"title":"Behaviors in Oxidation at 1100°C of an Equimolar CoNiFeMnCr High-Entropy Alloy and of its Versions Moderately Added with HfC or TaC Carbides","authors":"Patrice Berthod","doi":"10.1007/s11085-023-10170-6","DOIUrl":null,"url":null,"abstract":"<div><p>Three cast alloys based on a HEA composition were exposed to air at 1100°C for 50 h, a simple equimolar CoNiFeMnCr alloy, an equimolar CoNiFeMnCr alloy added with 3.7 wt.%Hf and 0.25 wt.%C, and an equimolar CoNiFeMnCr alloy added with 3.7 wt.%Ta and 0.25 wt.%C. The CoNiFeMnCr alloy is single-phase, and the two others are two-phase with a HEA matrix and either HfC or TaC interdendritic carbides. The three alloys resisted isothermal oxidation, with the formation of a M<sub>2</sub>O<sub>3</sub> scale comprised of Cr and Mn. In this scale, the relative proportions of Cr and Mn varied from the alloy/scale interface (much more Cr than Mn) to the scale/atmosphere interface (much more Mn than Cr). Internal oxidation took place too, with locally noticeable deep oxidation penetrations in the simple equimolar alloy. The carbides-containing alloys were also affected by internal oxidation (M<sub>2</sub>O<sub>3</sub>, HfO<sub>2</sub> and CrTaO<sub>4</sub>). Cr and Mn obviously diffused outward. Quantification of Cr and Mn lost by the alloys allowed for estimating the total oxide masses formed. The Cr and Mn losses were rather great, and equivalent values of parabolic constants were estimated to allow comparison with a model chromia-forming Ni-based binary alloy. The calculated oxidation kinetics were deduced to be faster than in the case of a pure chromia-forming behavior.</p></div>","PeriodicalId":724,"journal":{"name":"Oxidation of Metals","volume":null,"pages":null},"PeriodicalIF":2.1000,"publicationDate":"2023-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11085-023-10170-6.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Oxidation of Metals","FirstCategoryId":"88","ListUrlMain":"https://link.springer.com/article/10.1007/s11085-023-10170-6","RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"METALLURGY & METALLURGICAL ENGINEERING","Score":null,"Total":0}
引用次数: 0
Abstract
Three cast alloys based on a HEA composition were exposed to air at 1100°C for 50 h, a simple equimolar CoNiFeMnCr alloy, an equimolar CoNiFeMnCr alloy added with 3.7 wt.%Hf and 0.25 wt.%C, and an equimolar CoNiFeMnCr alloy added with 3.7 wt.%Ta and 0.25 wt.%C. The CoNiFeMnCr alloy is single-phase, and the two others are two-phase with a HEA matrix and either HfC or TaC interdendritic carbides. The three alloys resisted isothermal oxidation, with the formation of a M2O3 scale comprised of Cr and Mn. In this scale, the relative proportions of Cr and Mn varied from the alloy/scale interface (much more Cr than Mn) to the scale/atmosphere interface (much more Mn than Cr). Internal oxidation took place too, with locally noticeable deep oxidation penetrations in the simple equimolar alloy. The carbides-containing alloys were also affected by internal oxidation (M2O3, HfO2 and CrTaO4). Cr and Mn obviously diffused outward. Quantification of Cr and Mn lost by the alloys allowed for estimating the total oxide masses formed. The Cr and Mn losses were rather great, and equivalent values of parabolic constants were estimated to allow comparison with a model chromia-forming Ni-based binary alloy. The calculated oxidation kinetics were deduced to be faster than in the case of a pure chromia-forming behavior.
期刊介绍:
Oxidation of Metals is the premier source for the rapid dissemination of current research on all aspects of the science of gas-solid reactions at temperatures greater than about 400˚C, with primary focus on the high-temperature corrosion of bulk and coated systems. This authoritative bi-monthly publishes original scientific papers on kinetics, mechanisms, studies of scales from structural and morphological viewpoints, transport properties in scales, phase-boundary reactions, and much more. Articles may discuss both theoretical and experimental work related to gas-solid reactions at the surface or near-surface of a material exposed to elevated temperatures, including reactions with oxygen, nitrogen, sulfur, carbon and halogens. In addition, Oxidation of Metals publishes the results of frontier research concerned with deposit-induced attack. Review papers and short technical notes are encouraged.