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  • 1.
    Calamba, Katherine
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. University of Lorraine, France.
    Schramm, Isabella
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Saarland University, Germany.
    Johansson Jöesaar, Mats P.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. SECO Tools AB, Sweden.
    Ghanbaja, J.
    University of Lorraine, France.
    Pierson, J. F.
    University of Lorraine, France.
    Mucklich, F.
    Saarland University, Germany.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Enhanced thermal stability and mechanical properties of nitrogen deficient titanium aluminum nitride (Ti0.54Al0.46Ny) thin films by tuning the applied negative bias voltage2017In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 122, no 6, article id 065301Article in journal (Refereed)
    Abstract [en]

    Aspects on the phase stability and mechanical properties of nitrogen deficient (Ti0.54Al0.46)N-y alloys were investigated. Solid solution alloys of (Ti,Al)N were grown by cathodic arc deposition. The kinetic energy of the impinging ions was altered by varying the substrate bias voltage from -30V to -80 V. Films deposited with a high bias value of -80V showed larger lattice parameter, finer columnar structure, and higher compressive residual stress resulting in higher hardness than films biased at -30V when comparing their as-deposited states. At elevated temperatures, the presence of nitrogen vacancies and point defects (anti-sites and self-interstitials generated by the ion-bombardment during coating deposition) in (Ti0.54Al0.46)N-0.87 influence the driving force for phase separation. Highly biased nitrogen deficient films have point defects with higher stability during annealing, which cause a delay of the release of the stored lattice strain energy and then accelerates the decomposition tendencies to thermodynamically stable c-TiN and w-AlN. Low biased nitrogen deficient films have retarded phase transformation to w-AlN, which results in the prolongment of age hardening effect up to 1100 degrees C, i.e., the highest reported temperature for Ti-Al-N material system. Our study points out the role of vacancies and point defects in engineering thin films with enhanced thermal stability and mechanical properties for high temperature hard coating applications. Published by AIP Publishing.

  • 2.
    Chen, Yu-Hsiang
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Rogström, Lina
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Roa, JJ
    Departament de Ciència dels Materials i Enginyería Metal·lúrgica, Universitat Politècnica de Catalunya, EEBE-Campus Diagonal Besòs, Barcelona, Spain.
    Zhu, Jianqiang
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Schramm, Isabella
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Functional Materials, Department of Materials Science, Campus D3.3, Saarland University,Saarbrücken, Germany.
    Johnson, LJS
    Sandvik Coromant, SE-126 80 Stockholm, Sweden.
    Schell, N.
    Helmholtz-Zentrum Geesthacht (HZG), Geesthacht, Germany.
    Muecklich, F.
    Functional Materials, Department of Materials Science, Campus D3.3, Saarland University, Saarbrücken, Germany.
    Anglada, M. J.
    Departament de Ciència dels Materials i Enginyería Metal·lúrgica, Universitat Politècnica de Catalunya, EEBE-Campus Diagonal Besòs, Barcelona, Spain.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Thermal and mechanical stability of wurtzite-ZrA1N/cubic-TiN and wurtzite-ZrA1N/cubic-ZrN multilayers2017In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 324, p. 328-337Article in journal (Refereed)
    Abstract [en]

    The phase stability and mechanical properties of wurtzite (w)-Zr(0.25)A1(0.75)N/cubic (c)-TiN and w-Zr(0.25)A1(0.75)N/c-ZrN multilayers grown by arc evaporation are studied. Coherent interfaces with an orientation relation of c-TiN (111)[1-10]IIw-ZrAlN (0001)[11-20] form between ZrA1N and TiN sublayers during growth of the w-ZrAIN/c-TiN multilayer. During annealing at 1100 degrees C a c-Ti(Zr)N phase forms at interfaces between ZrA1N and TiN, which reduces the lattice mismatch so that the coherency and the compressive strain are partially retained, resulting in an increased hardness (32 GPa) after annealing. For the w-ZrAIN/c-ZrN multilayer, there is no coherency between sublayers leading to strain relaxation during annealing causing the hardness to drop. The retained coherency between layers and the compressive strain in the w-ZrAIN/c-TiN multilayer results in superior fracture toughness compared to the w-ZrAIN/c-ZrN multilayer as revealed by cross-sectional investigations of damage events under scratch and indentation tests. (C) 2017 Elsevier B.V. All rights reserved.

  • 3.
    Knutsson, Axel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Schramm, Isabella C.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology. Functional Materials, Department Materials Science, Saarland University, Saarbrücken, Germany.
    Asp Grönhagen, Klara
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Mücklich, F.
    Functional Materials, Department Materials Science, Saarland University, Saarbrücken, Germany.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Surface directed spinodal decomposition at TiAlN / TiN interfaces2013In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 11, p. 114305-1-114305-8Article in journal (Refereed)
    Abstract [en]

    In contrast to the monolithic c-Ti1-xAlxN, the isostructural spinodal decomposition to c-AlN and c-TiN of the c-Ti1-xAlxN/TiN multilayers have the same onset temperature regardless of composition (x=0.50 and 0.66). The onset is also located at a lower temperature compared to the monoliths with the same Al-content, revealed by differential scanning calorimetry. Zcontrast STEM imaging shows a decomposed structure of the multilayers at a temperature where it is not present in the monoliths. Atom probe tomography reveal the formation of an AlN-rich layer followed by a TiN-rich area parallel to the interface in the decomposed Ti0.34Al0.66N/TiN coating, consistent with surface directed spinodal decomposition. Phase field simulations predict such behavior and show that the surface directed spinodal decomposition is affected by in the internal interfaces, as deposited elemental fluctuations, coherency stresses and alloy composition.

  • 4.
    Schramm Benítez, Isabella Citlalli
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Defect-engineered (Ti,Al)N thin films2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis investigates the effect of point defects (nitrogen vacancies and interstitials) and multilayering ((Ti,Al)N/TiN) on the phase transformations in cathodic arc-evaporated cubic (Ti,Al)N thin films at elevated temperatures. Special attention is paid to the evolution of the beneficial spinodal decomposition into c-TiN and c-AlN, the detrimental formation of wurtzite AlN and the potential application as hard coating in cutting tools.

    c-(Ti1-xAlx)Ny thin films with varying Al fractions and N content (y = 0.93 to 0.75) show a delay in the spinodal decomposition when increasing the amount of N vacancies. This results in a 300 °C upshift in the age hardening and a delay in the w-AlN formation, while additions of self-interstitials enhance phase separation. High temperature interaction between hard metal substrates and thin films is more pronounced when increasing N deficiency through diffusion of substrate elements into the film. Low N content films (y = 0.58 to 0.40) showed formation of additional phases such as Ti4AlN3, Ti2AlN, Al5Ti2 and Al3Ti during annealing and a transformation from Ti2AlN to Ti4AlN3 via intercalation. The multilayer structure of TiN/TiAlN results in surfacedirected spinodal decomposition that affects the decomposition behavior. Careful use of these effects appears as a promising method to improve cutting tool performance.

    List of papers
    1. Impact of nitrogen vacancies on the high temperature behavior of (Ti1-xAlx)N-y alloys
    Open this publication in new window or tab >>Impact of nitrogen vacancies on the high temperature behavior of (Ti1-xAlx)N-y alloys
    Show others...
    2016 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 119, p. 218-228Article in journal (Refereed) Published
    Abstract [en]

    Substoichiometric solid solution alloys of cubic (Ti1-xAlx)N-y with x = 0.26, 0.48 and 0.60, and y ranging from 0.93 to 0.75 were grown by cathodic arc deposition. The influence of nitrogen deficiency on their thermal stability was studied by X-ray diffractometry, differential scanning calorimetry, scanning electron microscopy, and atom probe tomography. The nitrogen deficiency did not significantly affect the columnar growth nor the as deposited hardness. At elevated temperatures, alloys with x = 0.48 and 0.60 decompose isostructurally into cubic c-TiN and cubic c-AlN domains, which is consistent with spinodal decomposition. The decomposition is retarded by decreasing the nitrogen content, e.g. the formed isostructural domains in (Ti0.52Al0.48)N-0.92 at 900 degrees C are similar in size to (Ti0.52Al0.48)N-0.75 at 1200 degrees C. The formation of hexagonal w-AlN is shifted to higher temperatures by decreasing nitrogen content. Nucleation and growth of Al-Ti clusters in a Ti rich matrix were observed for the alloys with high Ti content, x = 0.26. These results suggest that nitrogen deficiency reduces the driving force for phase separation. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

    Place, publisher, year, edition, pages
    PERGAMON-ELSEVIER SCIENCE LTD, 2016
    Keywords
    TiAlN system; Nitrogen vacancies; Spinodal decomposition; Atom probe tomography; Thin films
    National Category
    Metallurgy and Metallic Materials
    Identifiers
    urn:nbn:se:liu:diva-132334 (URN)10.1016/j.actamat.2016.08.024 (DOI)000384778300021 ()
    Note

    Funding Agencies|Erasmus Mundus doctoral program DocMASE; Swedish Research Council VR [621-2012-4401]; Swedish Foundation for Strategic Research, SSF via MultiFilms program [RMA08-0069]; Swedish government strategic research area grant AFM - SFO MatLiU [2009-00971]; VIN-NOVA (M - Era.net) [2013-02355(MC2)]; DFG; federal state government of Saarland [INST 256/298-1 FUGG]; AME-Lab (European Regional Development Fund) [C/4-EFRE-13/2009/Br]

    Available from: 2016-11-12 Created: 2016-11-01 Last updated: 2018-01-03
    2. Solid state formation of Ti4AlN3 in cathodic arc deposited (Ti1-xAlx)N-y alloys
    Open this publication in new window or tab >>Solid state formation of Ti4AlN3 in cathodic arc deposited (Ti1-xAlx)N-y alloys
    Show others...
    2017 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 129, p. 268-277Article in journal (Refereed) Published
    Abstract [en]

    Reactive cathodic arc deposition was used to grow substoichiometric solid solution cubic c-(Ti1-xAlx)N-y thin films. The films were removed from the substrate and then heated in an argon environment to 1400 degrees C. Via solid state reactions, formation of MAX phase Ti4AlN3 was obtained. Additional phases such as Ti2AlN, c-TiN, w-AIN, Al5Ti2 and Al3Ti were also present during the solid state reaction. Ti4AlN3 formation was observed in samples with an Al metal fraction x amp;lt; 0.63 and a nitrogen content 0.4 amp;lt; y amp;lt; 0.6. Regardless of the initial composition, formation of Ti4AlN3 started in Ti2AlN crystal plates in the temperature range between 1200 and 1400 degrees C. Accompanying the onset of Ti4AlN3 was the presence of an intermediate structure identified as Ti6Al2N4, consisting of alternating layers of intergrown Ti2AlN and Ti4AlN3 phases with a half-unit-cell stacking. We suggest that the formation of Ti4AlN3 occurred via intercalation of aluminum and nitrogen along the basal plane accompanied by a simultaneous detwinning process. In addition we propose that this formation mechanism can be used to obtain MAX phases of high n order. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

    Place, publisher, year, edition, pages
    PERGAMON-ELSEVIER SCIENCE LTD, 2017
    Keywords
    MAX phase; Intergrown phase; Thin films; Solid state reaction; Intercalation
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:liu:diva-137593 (URN)10.1016/j.actamat.2017.03.001 (DOI)000400033900026 ()
    Note

    Funding Agencies|European Unions Erasmus Mundus doctoral program DocMASE; Swedish Research Council [621-2012-4401]; Swedish government strategic research area grant AFM SFO MatLiU [2009-00971]; VINNOVA (M - Era.net project MC2) [2013-02355]; European Research Council under the European Communitys Seventh Framework Program (FP) [335383]; DFG; federal state government of Saarland [INST 256/298-1 FUGG, INST 256/431-1 FUGG]; European Regional Development Fund [AME-Lab C/4-EFRE-13/2009/Br]

    Available from: 2017-05-22 Created: 2017-05-22 Last updated: 2018-03-19
    3. Effects of nitrogen vacancies on phase stability and mechanical properties of arc deposited (Ti0.52Al0.48)Ny (y<1) coatings
    Open this publication in new window or tab >>Effects of nitrogen vacancies on phase stability and mechanical properties of arc deposited (Ti0.52Al0.48)Ny (y<1) coatings
    Show others...
    2017 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 330, no Supplement C, p. 77-86Article in journal (Refereed) Published
    Abstract [en]

    Nitrogen sub-stoichiometric (Ti0.52Al0.48)Ny (0.92 ≥ y  ≥ 0.46) coatings were grown in a mixed Ar/N2 atmosphere by cathodic arc deposition on cemented carbide (WC/Co-based) substrates. The coatings present a columnar structure with decreasing column widths from 250 to 60nm, due to a corresponding reduced N content, accompanied by changes in preferred orientation from 200 to 111 to 220. Among these, coatings prepared with 0.92≥y≥0.75 exhibit spinodal decomposition and consequently age hardening at elevated temperatures. A reduced N content upshifts the hardness maximum by >300 °C. For these samples, the high temperature treatment resulted in interdiffusion of substrate elements, Co and C, mainly along column boundaries. Nevertheless, no detrimental effect in the hardness could be correlated. Conversely, a low N content sample (y=0.46) presents significant lattice diffusion of substrate elements Co, C, W, and Ta in the coating. In this case, the substrate elements are present throughout the coating, forming additional phases such as c-Ti(C,N), c-Co(Al,Ti,W), and c-(Ti,W,Ta)(C,N), with an observed increased hardness from 16 to 25GPa. We suggest that the substitution of nitrogen by carbon and the solution of W and Ta in c-TiN are responsible for the observed hardening. Our investigation shows the potential of sub-stoichiometric (Ti1-xAlx)Ny coatings for high temperature applications such as cutting tools and puts forth corresponding criteria for N content selection.

    Place, publisher, year, edition, pages
    Elsevier, 2017
    Keywords
    TiAlN, Thin films, Nitrogen vacancies, Spinodal decomposition, Age hardening
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-142115 (URN)10.1016/j.surfcoat.2017.09.043 (DOI)000414819700010 ()2-s2.0-85030314026 (Scopus ID)
    Note

    Funding agencies: European Unions Erasmus Mundus doctoral program DocMASE; Swedish Research Council [621-2012-4401]; Swedish Government Strategic Research Area grant AFM - SFO MatLiU [2009-00971]; VINNOVA (M - Era.net project MC2 grant) [2013-02355]; DFG [INST 256/298-1 FU

    Available from: 2017-10-23 Created: 2017-10-23 Last updated: 2018-01-03Bibliographically approved
    4. Enhanced thermal stability and mechanical properties of nitrogen deficient titanium aluminum nitride (Ti0.54Al0.46Ny) thin films by tuning the applied negative bias voltage
    Open this publication in new window or tab >>Enhanced thermal stability and mechanical properties of nitrogen deficient titanium aluminum nitride (Ti0.54Al0.46Ny) thin films by tuning the applied negative bias voltage
    Show others...
    2017 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 122, no 6, article id 065301Article in journal (Refereed) Published
    Abstract [en]

    Aspects on the phase stability and mechanical properties of nitrogen deficient (Ti0.54Al0.46)N-y alloys were investigated. Solid solution alloys of (Ti,Al)N were grown by cathodic arc deposition. The kinetic energy of the impinging ions was altered by varying the substrate bias voltage from -30V to -80 V. Films deposited with a high bias value of -80V showed larger lattice parameter, finer columnar structure, and higher compressive residual stress resulting in higher hardness than films biased at -30V when comparing their as-deposited states. At elevated temperatures, the presence of nitrogen vacancies and point defects (anti-sites and self-interstitials generated by the ion-bombardment during coating deposition) in (Ti0.54Al0.46)N-0.87 influence the driving force for phase separation. Highly biased nitrogen deficient films have point defects with higher stability during annealing, which cause a delay of the release of the stored lattice strain energy and then accelerates the decomposition tendencies to thermodynamically stable c-TiN and w-AlN. Low biased nitrogen deficient films have retarded phase transformation to w-AlN, which results in the prolongment of age hardening effect up to 1100 degrees C, i.e., the highest reported temperature for Ti-Al-N material system. Our study points out the role of vacancies and point defects in engineering thin films with enhanced thermal stability and mechanical properties for high temperature hard coating applications. Published by AIP Publishing.

    Place, publisher, year, edition, pages
    American Institute of Physics (AIP), 2017
    National Category
    Other Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-140514 (URN)10.1063/1.4986350 (DOI)000407742400032 ()
    Note

    Funding Agencies|European Unions Erasmus Mundus doctoral program in Materials Science and Engineering (DocMASE); Swedish Research Council [621-2012-4401]; Swedish government strategic research area grant AFM - SFO MatLiU [2009-00971]; VINNOVA [2013-02355]; DFG; federal state government of Saarland [INST 256/298-1 FUGG]; European Regional Development Fund [AME-Lab C/4-EFRE-13/2009/Br]

    Available from: 2017-09-11 Created: 2017-09-11 Last updated: 2019-05-27
    5. Surface directed spinodal decomposition at TiAlN / TiN interfaces
    Open this publication in new window or tab >>Surface directed spinodal decomposition at TiAlN / TiN interfaces
    Show others...
    2013 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 11, p. 114305-1-114305-8Article in journal (Refereed) Published
    Abstract [en]

    In contrast to the monolithic c-Ti1-xAlxN, the isostructural spinodal decomposition to c-AlN and c-TiN of the c-Ti1-xAlxN/TiN multilayers have the same onset temperature regardless of composition (x=0.50 and 0.66). The onset is also located at a lower temperature compared to the monoliths with the same Al-content, revealed by differential scanning calorimetry. Zcontrast STEM imaging shows a decomposed structure of the multilayers at a temperature where it is not present in the monoliths. Atom probe tomography reveal the formation of an AlN-rich layer followed by a TiN-rich area parallel to the interface in the decomposed Ti0.34Al0.66N/TiN coating, consistent with surface directed spinodal decomposition. Phase field simulations predict such behavior and show that the surface directed spinodal decomposition is affected by in the internal interfaces, as deposited elemental fluctuations, coherency stresses and alloy composition.

    Place, publisher, year, edition, pages
    American Institute of Physics (AIP), 2013
    Keywords
    Surface directed spinodal decomposition, Titanium aluminium nitride, Phase field simulations, Atom probe tomography
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-84704 (URN)10.1063/1.4795155 (DOI)000316545200054 ()
    Note

    Funding Agencies|Swedish Foundation for Strategic Research (SSF) project Designed Multicomponent Coatings (MultiFilms)||Swedish Research Council (VR)||Erasmus Mundus doctoral program DocMASE||EU|C/4-EFRE-13/2009/Br|DFG||federal state government of Saarland|INST 256/298-1 FUGG|

    Available from: 2012-10-17 Created: 2012-10-17 Last updated: 2018-02-23Bibliographically approved
  • 5.
    Schramm, Isabella C.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Pauly, C.
    Functional Materials, Department Materials Science, Saarland University, Saarbrucken, Germany.
    Johansson Jõesaar, Mats P.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. SECO Tools AB, Fagersta, Sweden.
    Slawik, S.
    Functional Materials, Department Materials Science, Saarland University, Saarbrucken, Germany.
    Suarez, S.
    Functional Materials, Department Materials Science, Saarland University, Saarbrucken, Germany.
    Mücklich, F.
    Functional Materials, Department Materials Science, Saarland University, Saarbrucken, Germany.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Effects of nitrogen vacancies on phase stability and mechanical properties of arc deposited (Ti0.52Al0.48)Ny (y<1) coatings2017In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 330, no Supplement C, p. 77-86Article in journal (Refereed)
    Abstract [en]

    Nitrogen sub-stoichiometric (Ti0.52Al0.48)Ny (0.92 ≥ y  ≥ 0.46) coatings were grown in a mixed Ar/N2 atmosphere by cathodic arc deposition on cemented carbide (WC/Co-based) substrates. The coatings present a columnar structure with decreasing column widths from 250 to 60nm, due to a corresponding reduced N content, accompanied by changes in preferred orientation from 200 to 111 to 220. Among these, coatings prepared with 0.92≥y≥0.75 exhibit spinodal decomposition and consequently age hardening at elevated temperatures. A reduced N content upshifts the hardness maximum by >300 °C. For these samples, the high temperature treatment resulted in interdiffusion of substrate elements, Co and C, mainly along column boundaries. Nevertheless, no detrimental effect in the hardness could be correlated. Conversely, a low N content sample (y=0.46) presents significant lattice diffusion of substrate elements Co, C, W, and Ta in the coating. In this case, the substrate elements are present throughout the coating, forming additional phases such as c-Ti(C,N), c-Co(Al,Ti,W), and c-(Ti,W,Ta)(C,N), with an observed increased hardness from 16 to 25GPa. We suggest that the substitution of nitrogen by carbon and the solution of W and Ta in c-TiN are responsible for the observed hardening. Our investigation shows the potential of sub-stoichiometric (Ti1-xAlx)Ny coatings for high temperature applications such as cutting tools and puts forth corresponding criteria for N content selection.

  • 6.
    Schramm, Isabella
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. University of Saarland, Germany.
    Johansson Jöesaar, Mats P.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. SECO Tools AB, Sweden.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Muecklich, F.
    University of Saarland, Germany.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Impact of nitrogen vacancies on the high temperature behavior of (Ti1-xAlx)N-y alloys2016In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 119, p. 218-228Article in journal (Refereed)
    Abstract [en]

    Substoichiometric solid solution alloys of cubic (Ti1-xAlx)N-y with x = 0.26, 0.48 and 0.60, and y ranging from 0.93 to 0.75 were grown by cathodic arc deposition. The influence of nitrogen deficiency on their thermal stability was studied by X-ray diffractometry, differential scanning calorimetry, scanning electron microscopy, and atom probe tomography. The nitrogen deficiency did not significantly affect the columnar growth nor the as deposited hardness. At elevated temperatures, alloys with x = 0.48 and 0.60 decompose isostructurally into cubic c-TiN and cubic c-AlN domains, which is consistent with spinodal decomposition. The decomposition is retarded by decreasing the nitrogen content, e.g. the formed isostructural domains in (Ti0.52Al0.48)N-0.92 at 900 degrees C are similar in size to (Ti0.52Al0.48)N-0.75 at 1200 degrees C. The formation of hexagonal w-AlN is shifted to higher temperatures by decreasing nitrogen content. Nucleation and growth of Al-Ti clusters in a Ti rich matrix were observed for the alloys with high Ti content, x = 0.26. These results suggest that nitrogen deficiency reduces the driving force for phase separation. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  • 7.
    Schramm, Isabella
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Saarland University, Germany.
    Pauly, C.
    Saarland University, Germany.
    Johansson Jöesaar, Mats P
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. SECO Tools AB, Sweden.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Schmauch, J.
    Saarland University, Germany.
    Muecklich, F.
    Saarland University, Germany.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Solid state formation of Ti4AlN3 in cathodic arc deposited (Ti1-xAlx)N-y alloys2017In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 129, p. 268-277Article in journal (Refereed)
    Abstract [en]

    Reactive cathodic arc deposition was used to grow substoichiometric solid solution cubic c-(Ti1-xAlx)N-y thin films. The films were removed from the substrate and then heated in an argon environment to 1400 degrees C. Via solid state reactions, formation of MAX phase Ti4AlN3 was obtained. Additional phases such as Ti2AlN, c-TiN, w-AIN, Al5Ti2 and Al3Ti were also present during the solid state reaction. Ti4AlN3 formation was observed in samples with an Al metal fraction x amp;lt; 0.63 and a nitrogen content 0.4 amp;lt; y amp;lt; 0.6. Regardless of the initial composition, formation of Ti4AlN3 started in Ti2AlN crystal plates in the temperature range between 1200 and 1400 degrees C. Accompanying the onset of Ti4AlN3 was the presence of an intermediate structure identified as Ti6Al2N4, consisting of alternating layers of intergrown Ti2AlN and Ti4AlN3 phases with a half-unit-cell stacking. We suggest that the formation of Ti4AlN3 occurred via intercalation of aluminum and nitrogen along the basal plane accompanied by a simultaneous detwinning process. In addition we propose that this formation mechanism can be used to obtain MAX phases of high n order. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  • 8.
    Yalamanchili, K.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Wang, Fei
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Saarland University, Germany.
    Schramm, Isabella
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Saarland University, Germany.
    Andersson, J. M.
    Seco Tools AB, Sweden.
    Johansson Jöesaar, Mats P.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Seco Tools AB, Sweden.
    Tasnadi, Ferenc
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Muecklich, F.
    Saarland University, Germany.
    Ghafoor, Naureen
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Exploring the high entropy alloy concept in (AlTiVNbCr)N2017In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 636, p. 346-352Article in journal (Refereed)
    Abstract [en]

    We have explored the high entropy alloy (HEA) concept in the AlTiVNbCr-nitride material system. (AlTiVNbCr)N coatings synthesized by reactive cathodic arc deposition are close to an ideal cubic solid solution with a positive mean-field enthalpy of mixing of 0.06 eV/atom. First principle calculations showa higher thermodynamic stability for the solid solution relative to their binaries thereby indicating a possible entropy stabilization at a temperature above 727 degrees C. However, the elevated temperature annealing experiments show that the solid solution decomposes to w-AlN and c-(TiVNbCr)N. The limited thermal stability of the solid solution is investigated in relation to several thermodynamic parameters. We suggest that the HEA designed multiprincipal element (AlTiVNbCr) N solid solutions are in a metastable state. (C) 2017 Published by Elsevier B.V.

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