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Open AccessArticle

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

1
Institute of Materials Science and Engineering, Brno University of Technology, Technicka 2896/2, 61669 Brno, Czech Republic
2
Institute of Manufacturing Technology, Brno University of Technology, Technicka 2896/2, 61669 Brno, Czech Republic
3
CEITEC BUT, Brno University of Technology, Purkynova 123, 612 00 Brno, Czech Republic
*
Author to whom correspondence should be addressed.
Metals 2020, 10(9), 1186; https://doi.org/10.3390/met10091186
Received: 6 August 2020 / Revised: 26 August 2020 / Accepted: 28 August 2020 / Published: 3 September 2020
(This article belongs to the Special Issue Powder Metallurgy of High-Entropy Alloy)
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. View Full-Text
Keywords: contamination; mechanical alloying; spark plasma sintering; infrared detection; high-entropy alloy; austenitic stainless steel contamination; mechanical alloying; spark plasma sintering; infrared detection; high-entropy alloy; austenitic stainless steel
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MDPI and ACS Style

Moravcik, I.; Kubicek, A.; Moravcikova-Gouvea, L.; Adam, O.; Kana, V.; Pouchly, V.; Zadera, A.; Dlouhy, I. The Origins of High-Entropy Alloy Contamination Induced by Mechanical Alloying and Sintering. Metals 2020, 10, 1186. https://doi.org/10.3390/met10091186

AMA Style

Moravcik I, Kubicek A, Moravcikova-Gouvea L, Adam O, Kana V, Pouchly V, Zadera A, Dlouhy I. The Origins of High-Entropy Alloy Contamination Induced by Mechanical Alloying and Sintering. Metals. 2020; 10(9):1186. https://doi.org/10.3390/met10091186

Chicago/Turabian Style

Moravcik, Igor; Kubicek, Antonin; Moravcikova-Gouvea, Larissa; Adam, Ondrej; Kana, Vaclav; Pouchly, Vaclav; Zadera, Antonin; Dlouhy, Ivo. 2020. "The Origins of High-Entropy Alloy Contamination Induced by Mechanical Alloying and Sintering" Metals 10, no. 9: 1186. https://doi.org/10.3390/met10091186

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