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Polish Academy of Sciences

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Dominika Gorniewicz

Military University of Technology (PL)

Recent publications
1.  Kopeć M., Gorniewicz D., Kukla D., Barwińska I., Jóźwiak S., Sitek R., Kowalewski Z.L., Effect of plasma nitriding process on the fatigue and high temperature corrosion resistance of Inconel 740H nickel alloy, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1007/s43452-022-00381-0, pp.57-1-15, 2022

Abstract:
The paper presents a comparison of microhardness, fatigue and high temperature corrosion of Inconel 740H nickel alloy in its as-received state and the same material with nitrided surface layers. The nitrided layers were produced using traditional glow discharge nitriding (specimens nitriding on the cathode potential) and an active screen (specimens nitriding at the plasma potential). A microstructure of the layers was characterized through the scanning electron microscopy, X-ray energy dispersive spectroscopy and X-ray diffraction analysis. Mechanical properties of the nitrided Inconel 740H alloy were examined using microhardness measurements and standard fatigue tests. It was found that Inconel 740H with a nitrided surface exhibited an improved fatigue response of 50 MPa in the whole range of stress amplitudes from 350 to 650 MPa and almost 325% increase of hardness for plasma modified surface and 250% for cathode modified surface. Additionally, the application of cathode nitriding enhanced the corrosion resistance of the alloy in question and effectively protected it against a high temperature oxidation.

Keywords:
nitriding, nickel alloys, coatings, fatigue, corrosion

Affiliations:
Kopeć M. - IPPT PAN
Gorniewicz D. - Military University of Technology (PL)
Kukla D. - IPPT PAN
Barwińska I. - IPPT PAN
Jóźwiak S. - Military University of Technology (PL)
Sitek R. - Warsaw University of Technology (PL)
Kowalewski Z.L. - IPPT PAN
2.  Gorniewicz D., Przygucki H., Kopeć M., Karczewski K., Jóźwiak S., TiCoCrFeMn (BCC + C14) high-entropy alloy multiphase structure analysis based on the theory of molecular orbitals, Materials, ISSN: 1996-1944, DOI: 10.3390/ma14185285, Vol.14, No.18, pp.5285-1-16, 2021

Abstract:
High-entropy alloys (HEA) are a group of modern, perspective materials that have been intensively developed in recent years due to their superior properties and potential applications in many fields. The complexity of their chemical composition and the further interactions of main elements significantly inhibit the prediction of phases that may form during material processing. Thus, at the design stage of HEA fabrication, the molecular orbitals theory was proposed. In this method, the connection of the average strength of covalent bonding between the alloying elements (Bo parameter) and the average energy level of the d-orbital (parameter Md) enables for a preliminary assessment of the phase structure and the type of lattice for individual components in the formed alloy. The designed TiCoCrFeMn alloy was produced by the powder metallurgy method, preceded by mechanical alloying of the initial elementary powders and at the temperature of 1050 °C for 60 s. An ultra-fine-grained structured alloy was homogenized at 1000 °C for 1000 h. The X-ray diffraction and scanning electron microscopy analysis confirmed the correctness of the methodology proposed as the assumed phase structure consisted of the body-centered cubic (BCC) solid solution and the C14 Laves phase was obtained.

Keywords:
HEA, solid solution, laves phase, U-FAST sintering

Affiliations:
Gorniewicz D. - Military University of Technology (PL)
Przygucki H. - GeniCore Sp. z o.o. (PL)
Kopeć M. - IPPT PAN
Karczewski K. - Military University of Technology (PL)
Jóźwiak S. - Military University of Technology (PL)

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