Microstructures and mechanical properties of oxide dispersion strengthened CoCrFeNi high-entropy alloy produced by mechanical alloying and spark plasma sintering

Li, Ming Yang; Guo, Yiting; Wang, Hanlu; Shan, Jianfu; Chang, Yuqing

doi:10.1016/j.intermet.2020.106819

Cited by 50 publications

(7 citation statements)

References 52 publications

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“…Sintered samples [41][42][43], carbon contamination is of lesser magnitude than the oxygen contamination (as indeed the APT results suggested). In addition to the lack of PCA in the present study, this finding could be attributed to the greater amount of oxides, itself resulting from the presence of highly reactive elements.…”

Section: Oxygen Contaminationsupporting

confidence: 54%

Effects of mechanical activation on chemical homogeneity and contamination level in dual-phase AlCoCrFeNi high entropy alloy

Fourmont

Gallet

Hoummada

et al. 2021

Materials Chemistry and Physics

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AlCoCrFeNi High Entropy Alloys were here synthesized by the combination of Planetary Ball Milling and Spark Plasma Sintering at 1100 • C. The relatively low rotating speed led to a peculiar agglomerate state referred to as "Mechanical Activated". The reactive sintering of activated agglomerates leads to a unique dual phase microstructure: the sintered sample exhibited a distinctive nanostructured lamellar microstructure consisting of two main phases (FCC and BCC). Atom Probe Tomography (APT) was used to ensure that the sintered sample was chemically homogeneous at the nanoscale in each phase. APT also revealed the presence of a Cr-rich sigma phase and oxide nanoprecipitates. X-ray Photoelectron Spectrometry (XPS) results demonstrated that most of the oxygen originated from the commercial powders. Calphad calculations revealed that the presence of oxides could alter the microstructure by modifying the global chemical composition.

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Section: Oxygen Contaminationsupporting

confidence: 54%

Effects of mechanical activation on chemical homogeneity and contamination level in dual-phase AlCoCrFeNi high entropy alloy

Fourmont

Gallet

Hoummada

et al. 2021

Materials Chemistry and Physics

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“…Nevertheless, one of the biggest issues concerning materials prepared by powder metallurgy is contamination, due to a significantly larger surface area of the powders compared to the surface area of the bulk material with similar weight. Rarely, the contamination of powder materials and the resulting formation of oxides or carbides is addressed, such as the occurrence of Cr 7 C 3 , Cr 2 O 3 and MnCr 2 O 4 in mechanically alloyed CoCrFeNi alloy [3], where their particles have been shown to cause strengthening of the alloy, but decrease in ductility. Moreover, the contamination may be used as an efficient feedstock alternative on the production of ODS alloys, since PM procedures enable homogeneous distribution of oxides and/or carbides into a metal matrix.…”

Section: Introductionmentioning

confidence: 99%

“…In this light, the present work aims on elucidating the evolution of the contamination level on PM-produced high-entropy alloy powders in comparison with traditional 316L steel powders. More specifically, the CoCrFeNi composition was chosen due to its remarkable mechanical properties when prepared by PM [3,21]. A systematic characterization of powders at different times of milling and atmospheres was performed, especially regarding the increase of the amounts of oxygen, nitrogen, and carbon in each alloy.…”

Section: Introductionmentioning

confidence: 99%

The Origins of High-Entropy Alloy Contamination Induced by Mechanical Alloying and Sintering

Moravčík

Kubíček

Moravcikova-Gouvea

et al. 2020

Metals

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One of the prevailing problems for materials produced by powder metallurgy is contamination from various sources. This work deals with the influence of process parameters and presence of process control agents (PCA) on the contamination level of materials produced by means of mechanical alloying (MA) technology, densified with spark plasma sintering (SPS). The equiatomic CoCrFeNi high-entropy alloy (HEA) was manufactured by the said methodology. For clear comparison, the 316L austenitic steel powder was milled and densified with identical conditions as a reference material. Both materials were milled in argon and nitrogen atmospheres for various times from 5 to 30 h. Chemical analysis of contamination by carbon, oxygen, and nitrogen within the powder and bulk materials was carried out using combustion analyzers. The microstructural analysis of powders and bulk samples was carried out using scanning electron microscopy (SEM) with focus on contaminant phases. The results show that carbon contamination increases with milling time. It is caused by wear of milling vial and balls made from high-carbon steels. Increase of carbon content within consolidation using SPS was also observed. The oxygen contamination also increases with milling time. It is more pronounced in the CoCrFeNi alloy due to higher oxidation of powder surfaces prior to milling. Milling of powders using nitrogen atmosphere also causes an increase of nitrogen content in both HEA and AISI 316L. The use of PCA (ethanol) during milling even for a short time (30 min) causes significant increase of carbon and oxygen contamination. The ways to decrease contamination are discussed in the paper.

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“…[17] observed similar crystal phases using higher BPR (10:1). Comparing with the results presented in our work, the significant differences are (i) The Cr-depleted matrix phase, with chromium oxides and carbides precipitates, was denoted with a wide range of grain sizes, but the average grain size was smaller and (ii) there was lack of big particles of the Cr-rich phase [17,42,43]. These two facts show that afract higher BPR makes the process more efficient.…”

Section: Structural Transformation In Mechanically Alloyed and Sinter...mentioning

confidence: 66%

Microstructure and mechanical properties of mechanically-alloyed CoCrFeNi high-entropy alloys using low ball-to-powder ratio

Huo

Zieliński

et al. 2023

Journal of Alloys and Compounds

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Microstructures and mechanical properties of oxide dispersion strengthened CoCrFeNi high-entropy alloy produced by mechanical alloying and spark plasma sintering

Cited by 50 publications

References 52 publications

Effects of mechanical activation on chemical homogeneity and contamination level in dual-phase AlCoCrFeNi high entropy alloy

Effects of mechanical activation on chemical homogeneity and contamination level in dual-phase AlCoCrFeNi high entropy alloy

The Origins of High-Entropy Alloy Contamination Induced by Mechanical Alloying and Sintering

Microstructure and mechanical properties of mechanically-alloyed CoCrFeNi high-entropy alloys using low ball-to-powder ratio

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