liu.seSök publikationer i DiVA
Ändra sökning
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Systematic theoretical search for alloys with increased thermal stability for advanced hard coatings applications
Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
2013 (Engelska)Ingår i: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 15Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

State-of-the-art alloys for hard coating applications, such as TiAlN, are known to suffer from decreased hardness during heat treatment in excess of 900 °C due to the formation of detrimental wurtzite AlN phases. Recent research has shown that multicomponent alloying with additional transition metals (TMs) such as Cr can shift the onset of the phase transformations to higher temperatures, but a search for new alloys is generally time-consuming due to the large number of processes that influence material properties along with the large number of alloy compositions that have to be synthesized. To overcome this difficulty we carry out systematic first-principles calculations aimed at finding potential new multicomponent TM aluminum nitride alloys for advanced hard coating applications. We direct our search towards a specific property, the thermal stability of the coating. In particular, we concentrate on the thermodynamic stability of the cubic B1 TM–Al–N phase relative to the wurtzite phase, and choose the enthalpy difference between them as our search descriptor. We perform ab initio calculations for all TMs, considered as impurities in AlN, and identify the most promising candidates that may improve the thermal stability. We present arguments that these elements should be targeted in future in-depth studies, theoretical, as well as experimental.

Ort, förlag, år, upplaga, sidor
Institute of Physics: Open Access Journals / Institute of Physics (IoP) and Deutsche Physikalische Gesellschaft , 2013. Vol. 15
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
URN: urn:nbn:se:liu:diva-98663DOI: 10.1088/1367-2630/15/9/095010ISI: 000324462800002OAI: oai:DiVA.org:liu-98663DiVA, id: diva2:655270
Anmärkning

Funding Agencies|Swedish Foundation for Strategic Research (SSF)||SRL|10-0026|Swedish Research Council|621-2011-4426|

Tillgänglig från: 2013-10-10 Skapad: 2013-10-10 Senast uppdaterad: 2017-12-06
Ingår i avhandling
1. Theoretical understanding of stability of alloys for hard-coating applications and design
Öppna denna publikation i ny flik eller fönster >>Theoretical understanding of stability of alloys for hard-coating applications and design
2015 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

The performance of modern hard coating materials puts high demands on properties such as hardness, thermal stability and oxidation resistance. These properties not only depend on the chemical composition, but also on the structure of the material on a nanoscale. This kind of nanostructuring will change during use and can be both beneficial and detrimental as materials grown under non-equilibrium conditions transforms under heat treatment or pressure into other structures with significantly different properties. This thesis aims to reveal the physics behind the processes of phase stability and transformations and how this can be utilized to improve on the properties of this class of alloys. This has been achieved through the application of various methods of first-principles calculations and analysis of the results on the basis of thermodynamics and electronic structure theory.

Within multicomponent transition metal aluminum nitride alloys (TMAlN) a number of studies have been carried out and presented here on ways of improving high temperature stability and hardness. Most (TMAl)N and TMN prefer a cubic B1 structure while AlN is stable in a hexagonal B4 phase, but for the purposes of hard coatings the metastable cubic B1 AlN phase, isostructural with the TMN phase is desired. It will be shown how the introduction of additional alloying components, such as Cr, into (TiAl)N changes the thermodynamic stability of phases so that new intermediary and metastable phases are formed during decomposition. In the case of such a (CrAl)N phase it is shown to have greater thermodynamic stability in the cubic phase than the pure AlN, resulting in improved high temperature hardness. Also, the importance of treating not just the binodal decomposition through the formation energy relative to end products but also the impact of spinodal decomposition from its second derivative due to the topology of formation energy surfaces is emphasized in the thesis. The impact of pressure on the AlN phase has also been studied through the calculation of a P-T diagram of AlN as part of a (TiAl)N alloy.

During the study of chemical alloying of TM components into AlN the alloying of low concentrations of these TM were treated in great detail. What is generally referred to as the AlN phase in decomposition is not entirely pure and can be expected to contain traces of any alloying components, such as Ti and Cr or whatever other metals may be present. Low concentration alloying of Cr, on the order of 5-10% is also shown to be stable with regard to isostructural decomposition. Detailed analysis of the effect of Ti and Cr impurities in AlN has been carried out along with a systematic search of AlN alloyed with small amounts of other TM components. The impact of these impurities on the electronic structure and thermodynamic properties is analyzed and the general trends will be explained through the occupation of impurity states by d-like electrons.

Theoretical treatment of such impurities is not straightforward however. AlN is an s-p semiconductor with a wide band gap while TM impurities generate states of a d-like nature situated inside the band gap. Such localized impurity states are expected to give rise to magnetic effects due to spin dependent exchange, in addition strong correlation effects might have to be taken into account. For that reason the use of hybrid functionals with orbital corrections according to the mHSE+Vw scheme, developed specifically for this class of materials, has been used and shown to influence the results during calculation of impurities of Ti and Cr.

In nanocomposite multilayered structures, composed of very thin layers of one material sandwiched between slabs of another, such as layers of SiN between TiN or ZrN, the material properties are greatly affected by the interfaces. In addition to the thermodynamic effects and lattice strains of the interfaces one also has to consider the atomic vibrational motion in the interface structure. Hence, dynamical stability of these thin multilayers is of great importance. As part of this thesis, results on the thermodynamic and dynamical stability of both TiN-SiN layers and ZrN-SiN will be presented. It will be shown that due to considerable dynamical instability in the interface structure of monolayered B1 SiN sandwiched between isostructural layers of B1 ZrN along (111) interfaces this structure cannot be expected to grow, instead preferring the stable (001) direction of growth.

Ort, förlag, år, upplaga, sidor
Linköping: Linköping University Electronic Press, 2015. s. 73
Serie
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1647
Nationell ämneskategori
Fysik Materialteknik
Identifikatorer
urn:nbn:se:liu:diva-115405 (URN)10.3384/diss.diva-115405 (DOI)978-91-7519-112-6 (ISBN)
Disputation
2015-04-10, Planck, Fysikhuset, Campus Valla, Linköping, 13:15 (Engelska)
Opponent
Handledare
Tillgänglig från: 2015-03-16 Skapad: 2015-03-16 Senast uppdaterad: 2019-11-15Bibliografiskt granskad

Open Access i DiVA

fulltext(772 kB)172 nedladdningar
Filinformation
Filnamn FULLTEXT01.pdfFilstorlek 772 kBChecksumma SHA-512
76c772b3361ca84634533b85381160d9d10cc9fb3f66a26182927d9be44777fe5c711a96749ee490b3ff6c3ecfd55ea00115535f37eec77bc4fa154d3a86db70
Typ fulltextMimetyp application/pdf

Övriga länkar

Förlagets fulltext

Personposter BETA

Lind, HansTasnadi, FerencAbrikosov, Igor

Sök vidare i DiVA

Av författaren/redaktören
Lind, HansTasnadi, FerencAbrikosov, Igor
Av organisationen
Teoretisk FysikTekniska högskolan
I samma tidskrift
New Journal of Physics
Teknik och teknologier

Sök vidare utanför DiVA

GoogleGoogle Scholar
Totalt: 172 nedladdningar
Antalet nedladdningar är summan av nedladdningar för alla fulltexter. Det kan inkludera t.ex tidigare versioner som nu inte längre är tillgängliga.

doi
urn-nbn

Altmetricpoäng

doi
urn-nbn
Totalt: 1312 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf