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Khatibi, Ali
Publications (10 of 20) Show all publications
Khatibi, A. (2013). Growth and Heat Treatment Studies of Al-Cr-O and Al-Cr-O-N Thin Films. (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Growth and Heat Treatment Studies of Al-Cr-O and Al-Cr-O-N Thin Films
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Aluminum oxide based thin films are applied on cutting tool inserts as a top layer to protect the underlying nitride or carbide functional layer from the harsh working environment in terms of abrasive and chemical wear under thermal and pressure load. This Thesis explores the synthesis and characterization of the next generations of multifunctional wear-resistant thin film coatings in the form of Al-Cr-O and Al-Cr-O-N compounds. The experiments include the deposition of oxide films by reactive magnetron sputtering and cathodic arc evaporation as well as investigation of structural and mechanical properties in as-deposited and annealed states. Ternary (Al1-xCrx)2+yO3-y films were deposited on Si(001) and WC-Co substrates kept at 400-575 °C from elemental Al and Cr or alloyed Al/Cr cathodes in Ar/O2, O2/N2, and pure O2 atmospheres. Also, quaternary (Al1-xCrx)2+z(O1-yNy)3-z films were deposited at substrate temperature of ~400 °C on WC-Co substrates in O2/N2 atmosphere. X-ray diffraction and analytical electron microscopy combined with ab initio calculations showed the existence of a new face centered cubic (Al,Cr)2O3 phase with 33% vacancies on the metallic Al/Cr sites. Increasing the temperature during annealing of these metastable cubic films resulted in phase transformation to corundum solid solution in the temperature range of 900-1100 °C. The apparent activation energy of this phase transformation process was calculated as 380-480 kJ/mol by using the Johnson-Mehl-Avrami model. The mechanical properties of the cubic and corundum oxide films were measured in terms of nanoindentation hardness and metal cutting performance. The cubic and corundum films showed hardness values of 26-28 GPa and 28-30 GPa, respectively. The oxynitride solid solution films showed to be predominantly cubic Al-Cr-N and cubic-(Al,Cr)2O3 and secondary corundum-(Al,Cr)2O3 with a hardness of ~30 GPa, slightly higher than Al-rich ternary oxides. Metal cutting performance tests showed that the good wear properties are mainly correlated to the oxygen-rich coatings, regardless of the cubic or corundum fractions.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2013. p. 79
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1497
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-87668 (URN)978-91-7519-710-4 (ISBN)
Public defence
2013-02-12, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2013-01-21 Created: 2013-01-21 Last updated: 2019-12-03Bibliographically approved
Khatibi, A., Genvad, A., Göthelid, E., Jensen, J., Eklund, P. & Hultman, L. (2013). Structural and Mechanical Properties of (AlxCr1-x)2+yO3-y Coatings Grown by Reactive Cathodic Arc Evaporation in As-deposited and Annealed States. Acta Materialia, 61(13), 4811-4822
Open this publication in new window or tab >>Structural and Mechanical Properties of (AlxCr1-x)2+yO3-y Coatings Grown by Reactive Cathodic Arc Evaporation in As-deposited and Annealed States
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2013 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 61, no 13, p. 4811-4822Article in journal (Refereed) Published
Abstract [en]

Coatings of (AlxCr1-x)2+yO3-y with 0.51≤x≤0.84 and 0.1≤y≤0.5 were deposited on hard cemented carbides substrates in an industrial cathodic arc evaporation system from powder-metallurgy prepared Cr/Al targets in pure O2 and O2+N2 atmospheres. The substrate temperature and bias in all the deposition runs were 575 °C and -120 V, respectively. The composition of the coatings measured by energy dispersive x-ray spectroscopy and elastic recoil detection analysis was the same as that of the targets. Microstructure analyses performed by symmetrical X-ray diffraction and transmission electron microscopy showed that corundum, cubic or mixed-phase coatings formed depending on the Cr/Al ratio of the coatings and O2 flow per activetarget during deposition. The corundum phase was promoted by high Cr content and high O2 flow per target, while the cubic phase was mostly observed for high Al content and low O2 flow per active target. In situ annealing of the cubic coatings resulted in phase transformation from cubic to corundum completed in the temperature range of 900-1100 °C, while corundum coatings retained their structure in the same range of annealing temperatures. Nanoindentation hardness of the coatings with Cr/Al ratio < 0.4 was 26-28 GPa, regardless of the structure. Increasing the Cr content of the coatings resulted in increased hardness of 28-30 GPa for corundum coatings. Wear resistance testing in a turning operation showed that coatings of Al-Cr-O have improved resistance to crater wear at the cost of flank wear compared to TiAlN coatings.

Place, publisher, year, edition, pages
Elsevier, 2013
Keywords
Physical vapor deposition (PVD); Ternary alloys; Alumina (α-Al2O3); Solid solution; Al-Cr-O alloys
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-87666 (URN)10.1016/j.actamat.2013.05.002 (DOI)000321601400011 ()
Available from: 2013-01-21 Created: 2013-01-21 Last updated: 2017-12-06Bibliographically approved
Alling, B., Khatibi, A., Simak, S., Eklund, P. & Hultman, L. (2013). Theoretical investigation of cubic B1-like and corundum (Cr1−xAlx)2O3 solid solutions. Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, 31(3)
Open this publication in new window or tab >>Theoretical investigation of cubic B1-like and corundum (Cr1−xAlx)2O3 solid solutions
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2013 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 31, no 3Article in journal (Refereed) Published
Abstract [en]

First-principles calculations are employed to investigate the stability and properties of cubic rock-salt-like (Cr1−xAlx)2O3 solid solutions, stabilized by metal site vacancies as recently reported experimentally. It is demonstrated that the metal site vacancies can indeed be ordered in a way that gives rise to a suitable fourfold coordination of all O atoms in the lattice. B1-like structures with ordered and disordered metal site vacancies are studied for (Cr0.5Al0.5)2O3 and found to have a cubic lattice spacing close to the values reported experimentally, in contrast to fluorite-like and perovskite structures. The obtained B1-like structures are higher in energy than corundum solid solutions for all compositions, but with an energy offset per atom similar to other metastable systems possible to synthesize with physical vapor deposition techniques. The obtained electronic structures show that the B1-like systems are semiconducting although with smaller band gaps than the corundum structure.

Place, publisher, year, edition, pages
American Vacuum Society, 2013
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-95510 (URN)10.1116/1.4795392 (DOI)000319349900002 ()
Note

E A3 05:192||Ingvar Carlsson Award 3||

Available from: 2013-07-05 Created: 2013-07-05 Last updated: 2017-12-06
Khatibi, A. (2012). Face-Centered Cubic and corundum (Al1-xCrx)2O3 Thin Films:  Deposition, Characterization, and Heat Treatment Studies. Paper presented at PSE 2012 - 13th International Conference on Plasma Surface Engineering, 10-14 September, Garmisch-Partenkirchen, Germany.
Open this publication in new window or tab >>Face-Centered Cubic and corundum (Al1-xCrx)2O3 Thin Films:  Deposition, Characterization, and Heat Treatment Studies
2012 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Manufacturing, Surface and Joining Technology Physical Sciences
Identifiers
urn:nbn:se:liu:diva-84382 (URN)
Conference
PSE 2012 - 13th International Conference on Plasma Surface Engineering, 10-14 September, Garmisch-Partenkirchen, Germany
Available from: 2012-10-05 Created: 2012-10-05 Last updated: 2012-10-11
Khatibi, A., Lu, J., Jensen, J., Eklund, P. & Hultman, L. (2012). Phase transformations in face centered cubic (Al0.32Cr0.68)(2)O-3 thin films. Surface & Coatings Technology, 206(14), 3216-3222
Open this publication in new window or tab >>Phase transformations in face centered cubic (Al0.32Cr0.68)(2)O-3 thin films
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2012 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 206, no 14, p. 3216-3222Article in journal (Refereed) Published
Abstract [en]

Face centered cubic (Al0.32Cr0.68)(2)O-3 thin films have been annealed in the temperature range of 500-1000 degrees C during 2-8 h. The fcc structure of the film remains intact when annealed at temperatures up to 700 degrees C for 8 h. X-ray diffraction and transmission electron microscopy show the onset of phase transformation to corundum phase alloys in the sample annealed at 900 degrees C for 2 h, where annealing at 1000 degrees C for 2 h results in complete phase transformation to alpha-(Al0.32Cr0.68)(2)O-3. In-plane and out-of-plane line scans performed in EDX TEM and theta/2 theta XRD patterns did not show any phase separation into alpha-Cr2O3 and Al2O3 prior and after the annealing. The apparent activation energy of this process is 380-480 kJ/mol as determined by the Johnson-Mehl-Avrami model.

Place, publisher, year, edition, pages
Elsevier, 2012
Keywords
fcc Al-Cr-O alloys, Phase transformation kinetics, Corundum solid solution, Annealing
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-76809 (URN)10.1016/j.surfcoat.2012.01.008 (DOI)000301903100009 ()
Note

Funding Agencies|Swedish Research Council (VR)||

Available from: 2012-10-15 Created: 2012-04-20 Last updated: 2017-12-07Bibliographically approved
Khatibi, A. (2012). Phase Transformations in Face Centered Cubic (Al,Cr)2O3 Thin Films. Paper presented at 39th International Conference on Metallurgical Coatings and Thin Films (ICMCTF), 23-27 April 2012, San Diego, USA.
Open this publication in new window or tab >>Phase Transformations in Face Centered Cubic (Al,Cr)2O3 Thin Films
2012 (English)Conference paper, Oral presentation only (Other academic)
Abstract [en]

Face centered cubic (Al1-xCrx)2O3 solid solution films, with x in the range 0.60<x<0.70, have been deposited using dual reactive RF magnetron sputtering from Al and Cr targets in mixed Ar/O2 discharge at a substrate temperature of 500 °C. The films have a strong <100> preferred orientation. The unit cell parameter is 4.04 Å determined by x-ray diffraction and high resolution transmission electron microscopy techniques. Nanoindentation shows that the films exhibit hardness values up to 26 GPa and reduced modulus of 220-235 GPa. In the present work, ex-situ annealing studies were performed on as-deposited samples for a series of temperatures up to 1000 °C and annealing time of 0-8 h. The fcc structure remains intact up to 700 °C. The onset of phase transformation from fcc to corundum is observed in the sample annealed at 900 °C for 2 h, where annealing for 2 h at 1000 °C results in complete transformation to a-(Al1-xCrx)2O3. There is no indication of any phase separation into a-Cr2O3 and Al2O3 prior and after the annealing, confirmed by the in-plane and out-of-plane line scans performed in EDX TEM and long-time small step size q/2q XRD patterns. The kinetics of phase transformation studied by the Jahnson-Avrami-Mehl model shows the apparent activation energy of the phase transformation process in the range of 380-480 kJ/mol. Ongoing work is focused on theoretical studies of the stability and composition of the structure of the as-deposited fcc-(Al1-xCrx)2O3 solid solution films, which are suggested to have a non-stoichiometric NaCl structure with 33% vacancy occupancy on Al/Cr sites.

National Category
Manufacturing, Surface and Joining Technology Physical Sciences
Identifiers
urn:nbn:se:liu:diva-84381 (URN)
Conference
39th International Conference on Metallurgical Coatings and Thin Films (ICMCTF), 23-27 April 2012, San Diego, USA
Available from: 2012-10-05 Created: 2012-10-05 Last updated: 2013-01-21
Khatibi, A., Sjolen, J., Greczynski, G., Jensen, J., Eklund, P. & Hultman, L. (2012). Structural and mechanical properties of Cr-Al-O-N thin films grown by cathodic arc deposition. Acta Materialia, 60(19), 6494-6507
Open this publication in new window or tab >>Structural and mechanical properties of Cr-Al-O-N thin films grown by cathodic arc deposition
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2012 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 60, no 19, p. 6494-6507Article in journal (Refereed) Published
Abstract [en]

Coatings of (CrxAl1-x)(delta)(O1-yNy)(xi) with 0.33 less than= x less than= 0.96, 0 less than= y less than= 1 and 0.63 less than= delta/xi less than= 1.30 were deposited using cathodic arc evaporation in N-2/O-2 reactive gas mixtures on 50 V negatively biased WC-10 wt.% Co substrates from different Cr and Al alloys with three different Cr/Al compositional ratios. For N-2 less than 63% of the total gas, ternary (Cr,Al)(2)O-3 films containing less than1 at.% of N forms; as determined by elastic recoil detection analysis. Increasing the N-2 fraction to 75% and above results in formation of quaternary oxynitride films. Phase analyses of the films by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy show the predominance of cubic Cr-Al-N and cubic-(Cr,Al)(2)O-3 solid solutions and secondary hexagonal alpha-(Cr,Al)(2)O-3 solid solution. High Cr and Al contents result in films with higher roughness, while high N and O contents result in smoother surfaces. Nanoindentation hardness measurements showed that Al-rich oxide or nitride films have hardness values of 24-28 GPa, whereas the oxynitride films have a hardness of similar to 30 GPa, regardless of the Cr and Al contents. Metal cutting performance tests showed that the good wear properties are mainly correlated to the oxygen-rich coatings, regardless of the cubic or corundum fractions.

Place, publisher, year, edition, pages
Elsevier, 2012
Keywords
Physical vapor deposition; Solid solution; Face-centered cubic crystals; Alumina (alpha-Al2O3); Oxynitride
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-87218 (URN)10.1016/j.actamat.2012.08.010 (DOI)000311188400006 ()
Available from: 2013-01-14 Created: 2013-01-14 Last updated: 2017-12-06
Khatibi, A. (2011). Activation energy of fcc-corundum phase transformation in (Al1-xCrx)2O3 Thin Films. Paper presented at 15th International Conference on Thin Films (ICTF-15), 8-11 November 2011, Kyoto, Japan.
Open this publication in new window or tab >>Activation energy of fcc-corundum phase transformation in (Al1-xCrx)2O3 Thin Films
2011 (English)Conference paper, Oral presentation only (Other academic)
Abstract [en]

Face centered cubic (Al1-xCrx)2O3 solid solution films, with x in the range 0.60<x<0.70, have been deposited using dual reactive RF magnetron sputtering from Al and Cr targets in mixed Ar/O2 discharge at a substrate temperature of 500 °C. The films have a strong <100> preferred orientation. The unit cell parameter is 4.04 Å determined by x-ray diffraction and high resolution transmission electron microscopy techniques. The (Al1-xCrx)2O3 films are suggested to have a non-stoichiometric NaCl structure with 33% vacancy occupancy on Al/Cr sites. Nanoindentation shows that the films exhibit hardness values up to 26 GPa and reduced modulus of 220-235 GPa. In the present work, in-situ annealing studies were performed on as-deposited samples for a series of temperatures up to 1000 °C and annealing time of 8 h. The fcc structure remains intact up to 700 °C. A gradual phase transformation from fcc to corundum at 1000 °C is observed, where annealing for 1-3 h yields a partial transformation and annealing for > 4 h results in complete transformation to a-(Al1-xCrx)2O3. There is no indication of any phase separation into a-Cr2O3 and Al2O3.

National Category
Manufacturing, Surface and Joining Technology Physical Sciences
Identifiers
urn:nbn:se:liu:diva-84379 (URN)
Conference
15th International Conference on Thin Films (ICTF-15), 8-11 November 2011, Kyoto, Japan
Available from: 2012-10-05 Created: 2012-10-05 Last updated: 2012-10-11
Khatibi, A. (2011). Deposition and Phase Transformations of Ternary Al-Cr-O Thin Films. (Licentiate dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Deposition and Phase Transformations of Ternary Al-Cr-O Thin Films
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis concerns the ternary Al-Cr-O system. (Al1-xCrx)2O3 solid solution thin films with 0.6<x<0.7 were deposited on Si(001) substrates at temperatures of 400-500 °C by reactive radio frequency magnetron sputtering from metallic targets of Al and Cr in a flow controlled Ar / O2 gas mixture. As-deposited and annealed (Al1-xCrx)2O3 thin films were analyzed by x-ray diffraction, elastic recoil detection analysis, scanning electron microscopy, transmission electron microscopy, and nanoindentation. (Al1-xCrx)2O3 showed to have face centered cubic structure with lattice parameter of 4.04 Å, which is in contrast to the typical corundum structure reported for these films. The as-deposited films exhibited hardness of ~ 26 GPa and elastic modulus of 220-235 GPa. Phase transformation from cubic to corundum (Al0.32Cr0.68)2O3 starts at 925 °C. Annealing at 1000 °C resulted in complete phase transformation, while no precipitates of alumina and chromia were observed. Studies on kinetics of phase transformation showed a two-step thermally activated process; phase transformation and grain growth with the apparent activation energies 213±162 and 945±27 kJ/mol, respectively.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2011. p. 29
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1474
Keywords
Thin Films, Hard Coatings
National Category
Other Physics Topics
Identifiers
urn:nbn:se:liu:diva-65700 (URN)LIU-TEK-LIC-2011:13 (Local ID)978-91-7393-210-3 (ISBN)LIU-TEK-LIC-2011:13 (Archive number)LIU-TEK-LIC-2011:13 (OAI)
Presentation
2011-04-15, Hörsal Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2011-12-05 Created: 2011-02-17 Last updated: 2020-02-03Bibliographically approved
Khatibi, A., Palisaitis, J., Höglund, C., Eriksson, A., Persson, P. O. Å., Jensen, J., . . . Hultman, L. (2011). Face-Centered Cubic (Al1-xCrx)2O3. Thin Solid Films, 519(8), 2426-2429
Open this publication in new window or tab >>Face-Centered Cubic (Al1-xCrx)2O3
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2011 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 8, p. 2426-2429Article in journal (Refereed) Published
Abstract [en]

We report the discovery of a face-centered cubic (Al1−xCrx)2O3 solid solution [0.60bxb0.70] in films grownonto Si substrates using reactive radio frequency magnetron sputtering from Al and Cr targets at 400 °C. Theproposed structure is NaCl-like with 33% vacancies on the metal sites. The unit cell parameter is 4.04 Å asdetermined by X-ray diffraction. The films have a b100N preferred crystallographic orientation and exhibithardness values up to 26 GPa and an elastic modulus of 220–235 GPa.

Place, publisher, year, edition, pages
Elsevier, 2011
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-65698 (URN)10.1016/j.tsf.2010.11.052 (DOI)000287631500008 ()
Funder
Swedish Research Council
Note
Original Publication: Ali Khatibi, Justinas Palisaitis, Carina Höglund, Anders Eriksson, Per O. Å. Persson, Jens Jensen, Jens Birch, Per Eklund and Lars Hultman, Face-Centered Cubic (Al1-xCrx)2O3 , 2011, Thin Solid Films, (519), 2426-2429. http://dx.doi.org/10.1016/j.tsf.2010.11.052 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/ Available from: 2011-02-21 Created: 2011-02-17 Last updated: 2017-12-11Bibliographically approved
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