Publication detail

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

MORAVČÍK, I. KUBÍČEK, A. MORAVČÍKOVA DE ALMEIDA GOUVÊA, L. ADAM, O. KAŇA, V. POUCHLÝ, V. ZÁDĚRA, A. DLOUHÝ, I.

English title

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

Type

journal article in Web of Science

Language

en

Original abstract

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.

English abstract

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.

Keywords in English

contamination; mechanical alloying; spark plasma sintering; infrared detection; high-entropy alloy; austenitic stainless steel

Released

03.09.2020

Publisher

MDPI

Location

Basel, Switzerland

ISSN

2075-4701

Volume

10

Number

9

Pages from–to

1–15

Pages count

15

BIBTEX


@article{BUT165147,
  author="Igor {Moravčík} and Antonín {Kubíček} and Larissa {Moravčíková de Almeida Gouvea} and Ondřej {Adam} and Václav {Kaňa} and Václav {Pouchlý} and Antonín {Záděra} and Ivo {Dlouhý},
  title="The Origins of High-Entropy Alloy Contamination Induced by Mechanical Alloying and Sintering",
  year="2020",
  volume="10",
  number="9",
  month="September",
  pages="1--15",
  publisher="MDPI",
  address="Basel, Switzerland",
  issn="2075-4701"
}