| 1. |
- Broering Chaar, Ana Beatriz, 1990-, et al.
(author)
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The Effect of Cathodic Arc Guiding Magnetic Field on the Growth of (Ti0.36Al0.64)N Coatings
- 2019
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In: Coatings. - : MDPI. - 2079-6412. ; 9:10
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Journal article (peer-reviewed)abstract
- We use a modified cathodic arc deposition technique, including an electromagnetic coil that introduces a magnetic field in the vicinity of the source, to study its influence on the growth of (Ti0.36Al0.64)N coatings. By increasing the strength of the magnetic field produced by the coil, the cathode arc spots are steered toward the edge of the cathode, and the electrons are guided to an annular anode surrounding the cathode. As a result, the plasma density between the cathode and substrate decreased, which was observed as a lateral spread of the plasma plume, and a reduction of the deposition rate. Optical emission spectroscopy shows reduced intensities of all recorded plasma species when the magnetic field is increased due to a lower number of collisions resulting in excitation. We note a charge-to-mass ratio decrease of 12% when the magnetic field is increased, which is likely caused by a reduced degree of gas phase ionization, mainly through a decrease in N2 ionization. (Ti0.36Al0.64)N coatings grown at different plasma densities show considerable variations in grain size and phase composition. Two growth modes were identified, resulting in coatings with (i) a fine-grained glassy cubic and wurtzite phase mixture when deposited with a weak magnetic field, and (ii) a coarse-grained columnar cubic phase with a strong magnetic field. The latter conditions result in lower energy flux to the coating’s growth front, which suppresses surface diffusion and favors the formation of c-(Ti,Al)N solid solutions over phase segregated c-TiN and w-AlN.
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| 2. |
- Calamba, Katherine, et al.
(author)
-
Dislocation structure and microstrain evolution during spinodal decomposition of reactive magnetron sputtered heteroepixatial c-(Ti-0.37,Al-0.63)N/c-TiN films grown on MgO(001) and (111) substrates
- 2019
-
In: Journal of Applied Physics. - : AMER INST PHYSICS. - 0021-8979 .- 1089-7550. ; 125:10
-
Journal article (peer-reviewed)abstract
- Heteroepitaxial c-(Ti-0.37,Al-0.63)N thin films were grown on MgO(001) and MgO(111) substrates using reactive magnetron sputtering. High resolution high-angle annular dark-field scanning transmission electron micrographs show coherency between the film and the substrate. In the as-deposited state, x-ray diffraction reciprocal space maps show a strained epitaxial film. Corresponding geometric phase analysis (GPA) deformation maps show a high stress in the film. At elevated temperature (900 degrees C), the films decompose to form iso-structural coherent c-Al- and c-TiN-rich domains, elongated along the elastically soft amp;lt;100amp;gt; directions. GPA analysis reveals that the c-TiN domains accommodate more dislocations than the c-AlN domains. This is because of the stronger directionality of the covalent bonds in c-AlN compared with c-TiN, making it more favorable for the dislocations to accumulate in c-TiN. The defect structure and strain generation in c-(Ti,Al)N during spinodal decomposition is affected by the chemical bonding state and elastic properties of the segregated domains.
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| 3. |
- Calamba, Katherine, et al.
(author)
-
Enhanced thermal stability and mechanical properties of nitrogen deficient titanium aluminum nitride (Ti0.54Al0.46Ny) thin films by tuning the applied negative bias voltage
- 2017
-
In: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 122:6
-
Journal article (peer-reviewed)abstract
- 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.
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| 4. |
- Calamba, Katherine, et al.
(author)
-
The effect of nitrogen vacancies on initial wear in arc deposited (Ti-0.52,Ti- Al-0.48)N-y, (y < 1) coatings during machining
- 2019
-
In: Surface & Coatings Technology. - : ELSEVIER SCIENCE SA. - 0257-8972 .- 1879-3347. ; 358, s. 452-460
-
Journal article (peer-reviewed)abstract
- Nitrogen deficient c-(Ti0.52Al0.48)Ny, y = 0.92, y = 0.87, and y = 0.75 coatings were prepared in different N-2/Ar discharges on WC-Co inserts by reactive cathodic arc deposition. The microstructure of the y = 0.92 coating show that spinodal decomposition has occurred resulting in the formation of coherent c-TiN- and c-AIN rich domains during cutting. The y = 0.87 and y = 0.75 coatings have exhibited a delay in decomposition due to the presence of nitrogen vacancies that lowers the free energy of the system. In the decomposed structure, grain boundaries and misfit dislocations enhance the diffusion of elements from the workpiece and the substrate (e.g. Fe, Cr, and Co) into the coatings and it becomes more susceptible to crater wear. The y = 0.87 sample displays the highest crater wear resistance because of its dense grain boundaries that prevent chemical wear. The y = 0.92 sample has the best flank wear resistance because the decomposition results in age hardening. The y = 0.75 sample contains the MAX-phase Ti(2)AIN after cutting. The chemical alteration within the y = 0.75 sample and its high amount of macroparticles cause its low wear resistance. The different microstructure evolution caused by different amount of N-vacancies result in distinctive interactions between chip and coating, which also causes difference in the initial wear mechanism of the (Ti,Al)/N-y coatings.
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| 5. |
- Chen, Yu-Hsiang, et al.
(author)
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Effects of decomposition route and microstructure on h-AlN formation rate in TiCrAlN alloys
- 2017
-
In: Journal of Alloys and Compounds. - : ELSEVIER SCIENCE SA. - 0925-8388 .- 1873-4669. ; 691, s. 1024-1032
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Journal article (peer-reviewed)abstract
- The phase evolution of cubic (c), solid solution TixCr-0.37Al1-0.37-x N alloys with x = 0.03 and 0.16, and the kinetics of the hexagonal (h)-AlN formation are studied via in situ wide angle x-ray scattering experiments during high temperature (1000-1150 degrees C) annealing. Spinodal decomposition was observed in Ti0.16Cr0.36Al0.48N while Ti0.03Cr0.38Al0.59N decomposes through nucleation and growth of h-AlN, c-TiN and c-CrAlN. h-AlN is formed from c-CrAlN domains in both cases and the formation rate of h-AlN depends on the stability of the c-CrAlN domains. In Ti0.16Cr0.36Al0.48N, the c-CrAlN domains are stabilized by crystallographic coherency with the surrounding c-TiCrN in a microstructure originating from spinodal decomposition. This results in lower formation rates of h-AlN for this composition. These differences are reflected in higher activation energy for h-AlN formation in Ti0.16Cr0.36Al0.48N compared to Ti0.03Cr0.38Al0.59N. It also points out different stabilities of the intermediate phase c-CrAlN during phase decomposition of TiCrAlN alloys. Additional contributions to the low activation energy for formation of h-AlN in Ti0.03Cr0.38Al0.59N stems from precipitation at grain boundaries. (C) 2016 Elsevier B.V. All rights reserved.
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| 6. |
- Engberg, David L. J., et al.
(author)
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Solid Solution and Segregation Effects in Arc-Deposited Ti1-xSixN Thin Films Resolved on the nanometer scale by 15N Isotopic Substitution in AtomP robe Tomography
-
Other publication (other academic/artistic)abstract
- Nanostructured TiSiN is an important material in wear--‐resistant coatings for extending the lifetime of cutting tools. Yet, the understanding regarding the structure, phase composition, and bonding on the detailed nanometer scale, which determines the properties of TiSiN, is lacking. This limits our understanding of the growth phenomena and eventually a larger exploitation of the material. By substituting natN2 with 15N2 during reactive arc deposition of TiSiN thin films, atom probe tomography (APT) gives elemental sensitivity and sub-nanometer resolution, a finer scale than what can be obtained by commonly employed energy dispersive electron spectroscopy in scanning transmission electron microscopy. Using a combination of analytical transmission electron microscopy and APT we show that arc-deposited Ti0.92Si0.0815N and Ti0.81Si0.1915N exhibit Si segregation on the nanometer scale in the alloy films. APT composition maps and proximity histograms from domains with higher than average Ti content show that the TiN domains contain at least ~2 at. % Si for Ti0.92Si0.08N and ~5 at. % Si for Ti0.81Si0.19N, thus confirming the formation of solid solutions. The formation of relatively pure SiNy domains in the Ti0.81Si0.19N films is tied to pockets between microstructured, columnar features in the film. Finer SiNy enrichments seen in APT possibly correspond to tissue layers around TiN crystallites, thus effectively hindering growth of TiN crystallites, causing TiN renucleation and thus explaining the featherlike nanostructure within the columns of these films. For the stoichiometry of the TiN phase, we establish a global under stoichiometry, in accordance with the tendency for SiNy films to have tetrahedral bonding coordination towards a nominal Si3N4 composition.
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| 7. |
- Johansson Jöesaar, Mats P., et al.
(author)
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Anisotropy effects onmicrostructure and properties in decomposed arc evaporated Ti1-xAlxN coatings during metal cutting
- 2013
-
In: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 235:25, s. 181-185
-
Journal article (peer-reviewed)abstract
- Anisotropy effects on the spinodal decomposition in cathodic arc evaporated cubic “phase c-Ti1−xAlxN coatingshave been studied with respect to composition, microstructure and hardness properties before and after a continuousturning operation. Coatings are simultaneously being exposed to both a high temperature and high pressureduring the metal cutting process. As evident from the current results, a high Al content coating, x = 0.66,when exposed to such extreme conditions decomposes into cubic c-AlN and c-TiN-rich domains. In this case,the evolving microstructure comprises interconnected spatially periodic, elongated and coherent cubic c-AlNand c-TiN-rich regions aligned along elastic compliant b100N crystal direction. A significantly different microstructurewith randomly oriented domains is observed for a coating with an elemental composition closer tothe isotropic limit, x = 0.28, exposed under the same conditions. From a coating hardness perspective, thenanoindentation results display a minor age hardening effect for the c-Ti1−xAlxN coating grown at x = 0.28while the coating grown with x = 0.66 exhibits a significant age-hardening effect of about 18%. We concludethat both microstructure and age hardening behavior during spinodal decomposition of c-Ti1−xAlxN correlateto the relative amount ofmetal Ti/Al ratio and consequently to the elastic anisotropy of the as-grown coatingmaterial.These results provide newinsights to the understanding of improvedwear resistance of c-Ti1−xAlxN withAl content during metal cutting.
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| 8. |
- Moreno, Maiara, et al.
(author)
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Adhesive wear of TiAlN coatings during low speed turning of stainless steel 316L
- 2023
-
In: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 524-525
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Journal article (peer-reviewed)abstract
- The wear behavior of TiAlN coatings during turning of stainless steel 316L at low cutting speeds (60–120 m/min) was investigated using scanning electron microscopy. In this speed range, the coatings fail by fracture due to an adhesive wear mechanism. The fracture of the coating is described in detail, including the strong influence of Al-content and cutting speed on the rate of wear. Low Al-content (x ≤ 0.23) coatings showed worse wear resistance than high Al-content (x ≥ 0.53) samples. Less substrate is exposed when the cutting speed is increased, because of reduced adhesive wear. The TiN and Ti0.77Al0.23N coatings are severely worn for all cutting speeds while Ti0.47Al0.53N and Ti0.38Al0.62N remain essentially unaffected at the highest speed. The difference in wear behavior is interpreted as a difference in the fracture toughness of the coatings.
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| 9. |
- Moreno, Maiara, et al.
(author)
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Crater wear mechanism of TiAlN coatings during high-speed metal turning
- 2021
-
In: Wear. - : Elsevier Science. - 0043-1648 .- 1873-2577. ; 484
-
Journal article (peer-reviewed)abstract
- The influence of the aluminium content (x) on crater wear mechanisms of Ti1-xAlxN coated WC-Co inserts in highspeed turning of 316L stainless steel was investigated. Electron microscopy and energy dispersive X-ray spectroscopy were used to characterize the wear behaviour. Ti1-xAlxN coatings with x <= 0.53 showed, after 1/3 of the tool life, a thick adhered layer composed of oxides and metallic species from the steel, and no diffusion of workpiece material into the coating. These coatings presented the best wear resistance and least abrasive wear. The high aluminium content Ti0.38Al0.62N coating showed the worst crater wear resistance. This is assigned to interdiffusion of workpiece elements and oxygen into the coating as a consequence of spinodal decomposition of the cubic TiAlN-phase, resulting in more severe abrasive wear.
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| 10. |
- Moreno, Maiara, 1993-, et al.
(author)
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Strain and phase evolution in TiAlN coatings during high-speed metal cutting : An in operando high-energy x-ray diffraction study
- 2024
-
In: Acta Materialia. - : Elsevier. - 1359-6454 .- 1873-2453. ; 263
-
Journal article (peer-reviewed)abstract
- We report on phase and strain changes in Ti1-xAlxN (0 ≤ x ≤ 0.61) coatings on cutting tools during turning recorded in operando by high-energy x-ray diffractometry. Orthogonal cutting of AISI 4140 steel was performed with cutting speeds of 360–370 m/min. Four positions along the tool rake face were investigated as a function of time in cut. Formation of γ-Fe in the chip reveals that the temperature exceeds 727 °C between the tool edge and the middle of the contact area when the feed rate is 0.06 mm/rev. Spinodal decomposition and formation of wurtzite AlN occurs at the positions of the tool with the highest temperature for the x ≥ 0.48 coatings. The strain evolution in the chip reveals that the mechanical stress is largest closest to the tool edge and that it decreases with time in cut for all analyzed positions on the rake face. The strain evolution in the coating varies between coatings and position on the rake face of the tool and is affected by thermal stress as well as the applied mechanical stress. Amongst others, the strain evolution is influenced by defect annihilation and, for the coatings with highest Al-content (x ≥ 0.48), phase changes.
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| 11. |
- Norrby, Niklas, et al.
(author)
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Improved metal cutting performance with biasmodulated textured Ti0.50Al0.50N multilayers
- 2014
-
In: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 257, s. 102-107
-
Journal article (peer-reviewed)abstract
- In this work we present the cutting performance of Ti0.50Al0.50N coatings which have been deposited with both a fixed and an alternating bias of -35 V and -70 V together with a Ti0.33Al0.67N reference coating grown at -35 V. The bias-modulated coatings were grown with different bias-layer periods, from 200 to 1200 nm. For the layers deposited with a fixed bias, a transition from a (100) to a (111) preferred orientation was observed with the change in bias from -35 V to -70 V. The coatings grown with an alternating bias, however, showed a (111) preferred orientation with an intensity that slightly depends on bias-layer period. Metal cutting performance in terms of crater and flank wear resistance show an improvement for all bias-layered coatings. This is attributed to a (111) oriented refined grain structure in combination with low residual stresses in the coating.
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| 12. |
- Norrby, Niklas, et al.
(author)
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In-situ x-ray scattering study of the cubic to hexagonal transformation of AlN in Ti1-xAlxN
- 2014
-
In: Acta Materialia. - : Elsevier. - 1359-6454 .- 1873-2453. ; 73, s. 205-214
-
Journal article (peer-reviewed)abstract
- In the present work, we have studied the decomposition of arc evaporated Ti0.55Al0.45N and Ti0.36Al0.64N during heat treatment in vacuum by in-situ synchrotron wide angle x-ray scattering primarily to characterize the kinetics of the phase transformation of AlN from the cubic NaCl-structure to the hexagonal wurtzite-structure. In addition, in-situ small angle x-ray scattering measurements were conducted to explore details of the wavelength evolution of the spinodal decomposition, thus providing information about the critical size of the c-AlN rich domains prior to the onset of the h-AlN transformation. We report the fractional cubic to hexagonal transformation of AlN in Ti1-xAlxN as a function of time and extract activation energies between 320 and 350 kJ/mol dependent on alloy composition. The onset of the hexagonal transformation occurs at about 50 K lower temperature in Ti0.36Al0.64N compared to Ti0.55Al0.45N where the high Al content alloy also has a significantly higher transformation rate. A critical wavelength for the cubic domains of about 13 nm was observed for both alloys. Scanning transmission electron microscopy shows a c-TiN/h-AlN microstructure with a striking morphology resemblance to the c-TiN/c-AlN microstructure present prior to the hexagonal transformation.
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| 13. |
- Pinchuk, Nataliia, et al.
(author)
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INFLUENCE OF DEPOSITION CONDITIONS ON MICROSTRUCTURE AND TEXTURE OF Ti1-XAlXN PVD COATINGS
- 2024
-
In: NANOCON Conference Proceedings - International Conference on Nanomaterials. - : TANGER Ltd.. - 9788088365150 ; , s. 112-117
-
Conference paper (peer-reviewed)abstract
- This study is focused on how the application of pulsed substrate bias during cathodic arc deposition affects the microstructure, texture, grain size and phase composition of (Ti,Al)N coatings. A series of Tix-1AlxN, 0.25≤x≤0.55 coatings were deposited on WC-Co cemented carbide substrates with -30 V, -60 V and -300 V pulsing bias (duty cycle 10 % and a frequence of 1 kHz) under controlled chamber conditions at 4.5 Pa N2-gas and a substrate temperature about 400 °C. The pulsing parameters for the bias (voltage, duty cycle and frequency) were deliberately selected to influence structure, microstructure and composition of the deposited coatings. All Tix-1AlxN coatings had a consistent columnar cubic B1 structure regardless of their chemical composition. Coatings grown at -30 V and -60 V pulsed bias exhibited a pronounced <111> texture attributed to a kinetically driven mechanism influenced by the relative flux of ion species, affecting the surface migration of adatoms during growth. In contrast, the coatings grown with a pulsed bias of -300 V exhibited a reduced <111> texture and the onset of grains with <100> preferred orientation. The transition to the <100> orientation with increased ion energy agrees with the fact that the <111> directions expose the densest array of atoms to the ion beam during growth while the <100> are the most open channeling directions in a B1 structure. The correlation to the preferred with respect to pulsing conditions during growth, correlated to microstructure, grain size and phase composition be further discussed. Surface roughness was highest (Sa≈0.17-0.22 µm) for coating deposited at pulsed bias -30 V.
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| 14. |
- Rogström, Lina, et al.
(author)
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A custom built lathe designed for in operando high-energy x-ray studies at industrially relevant cutting parameters
- 2019
-
In: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 90:10
-
Journal article (peer-reviewed)abstract
- We present a custom built lathe designed for in operando high-energy x-ray scattering studies of the tool-chip and tool-workpiece contact zones during operation. The lathe operates at industrially relevant cutting parameters, i.e., at cutting speeds amp;lt;= 400 m/min and feeds amp;lt;= 0.3 mm/rev. By turning tests in carbon steel, performed at the high-energy material science beamline P07 at Petra III, DESY, Hamburg, we observe compressive strains in TiNbAlN and Al2O3/Ti(C, N) coatings on the tool flank face during machining. It is demonstrated that by the right choice of substrate and coating materials, diffraction patterns can be recorded and evaluated in operando, both from the tool-workpiece and tool-chip contacts, i.e., from the contact zones between the tool and the workpiece material on the tool flank and rake faces, respectively. We also observe that a worn tool results in higher temperature in the tool-chip contact zone compared to a new tool. Published under license by AIP Publishing.
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| 15. |
- Rogström, Lina, et al.
(author)
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Wear behavior of ZrAlN coated cutting tools during turning
- 2015
-
In: Surface & Coatings Technology. - : ELSEVIER SCIENCE SA. - 0257-8972 .- 1879-3347. ; 282, s. 180-187
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Journal article (peer-reviewed)abstract
- In this study we explore the cutting performance of ZrAlN coatings. WC:Co cutting inserts coated by cathodic arc evaporated Zr1-xAlxN coatings with x between 0 and 0.83 were testeciin a longitudinal turning operation. The progress of wear was studied by optical microscopy and the used inserts were studied by electron microscopy. The cutting performance was correlated to the coating composition and the best performance was found for the coating with highest Al-content consisting of a wurtzite ZrAlN phase which is assigned to its high thermal stability. Material from the work piece was observed to adhere to the inserts during turning and the amount of adhered material and its chemical composition is independent on the Al-content of the coating. (C) 2015 Elsevier B.V. All rights reserved.
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| 16. |
- Schramm, Isabella, et al.
(author)
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Impact of nitrogen vacancies on the high temperature behavior of (Ti1-xAlx)N-y alloys
- 2016
-
In: Acta Materialia. - : PERGAMON-ELSEVIER SCIENCE LTD. - 1359-6454 .- 1873-2453. ; 119, s. 218-228
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Journal article (peer-reviewed)abstract
- 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.
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| 17. |
- Schramm, Isabella, et al.
(author)
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Solid state formation of Ti4AlN3 in cathodic arc deposited (Ti1-xAlx)N-y alloys
- 2017
-
In: Acta Materialia. - : PERGAMON-ELSEVIER SCIENCE LTD. - 1359-6454 .- 1873-2453. ; 129, s. 268-277
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Journal article (peer-reviewed)abstract
- 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.
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| 18. |
- Schroeder, Jeremy, et al.
(author)
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Industry-relevant magnetron sputtering and cathodic arc ultra-high vacuum deposition system for in situ x-ray diffraction studies of thin film growth using high energy synchrotron radiation
- 2015
-
In: Review of Scientific Instruments. - : AMER INST PHYSICS. - 0034-6748 .- 1089-7623. ; 86:9, s. 095113-
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Journal article (peer-reviewed)abstract
- We present an industry-relevant, large-scale, ultra-high vacuum (UHV) magnetron sputtering and cathodic arc deposition system purposefully designed for time-resolved in situ thin film deposition/annealing studies using high-energy (greater than50 keV), high photon flux (greater than10(12) ph/s) synchrotron radiation. The high photon flux, combined with a fast-acquisition-time (less than1 s) two-dimensional (2D) detector, permits time-resolved in situ structural analysis of thin film formation processes. The high-energy synchrotron-radiation based x-rays result in small scattering angles (less than11 degrees), allowing large areas of reciprocal space to be imaged with a 2D detector. The system has been designed for use on the 1-tonne, ultra-high load, high-resolution hexapod at the P07 High Energy Materials Science beamline at PETRA III at the Deutsches Elektronen-Synchrotron in Hamburg, Germany. The deposition system includes standard features of a typical UHV deposition system plus a range of special features suited for synchrotron radiation studies and industry-relevant processes. We openly encourage the materials research community to contact us for collaborative opportunities using this unique and versatile scientific instrument. (C) 2015 AIP Publishing LLC.
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| 19. |
- Yalamanchili, K., et al.
(author)
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Exploring the high entropy alloy concept in (AlTiVNbCr)N
- 2017
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In: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 636, s. 346-352
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Journal article (peer-reviewed)abstract
- 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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| 20. |
- Yalamanchili, Kumar, et al.
(author)
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Structure, deformation and fracture of arc evaporated Zr-Si-N ternary hard films
- 2014
-
In: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 258, s. 1100-1107
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Journal article (peer-reviewed)abstract
- Zr-Si-N films with varying Si contents were grown on WC-Co substrates with an industrial scale reactive cathodic arc deposition technique. The microstructural changes correlate to variation in mechanical properties with different deformation mechanisms dominating for different structures. Si forms a substitutional solid solution in the cubic ZrN lattice up to 1.8 at. % in a fine columnar structure. Further Si additions results in precipitation of an amorphous (a)-SiNX phase and evolution of a nanocomposite structure (nc ZrN-a SiNX) which has completely suppressed the columnar structure at 6.3 at. % Si. The rotation-induced artificial layering during film growth was used as a marker to visualize the deformation of the film. A dislocation-based homogeneous plastic deformation mechanism dominates the columnar structure, while grain boundary sliding is the active mechanism mediating heterogeneous plastic deformation in the nanocomposite structure. Film hardness increases with increasing Si content in the columnar structure due to an effective solid solution strengthening. The deformation mechanism of localized grain boundary sliding in the nanocomposite structure results in lower hardness. When cracking is induced by indentation, the fine columnar structure exhibits pronounced crack deflection that results in higher fracture resistance compared to the nanocomposite films.
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| 21. |
- Yang, Jing, et al.
(author)
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Contact damage resistance of TiN-coated hardmetals: Beneficial effects associated with substrate grinding
- 2015
-
In: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 275, s. 133-141
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Journal article (peer-reviewed)abstract
- Contact loading is a common service condition for coated hardmetal tools and components. Substrate grinding represents a key step within the manufacturing chain of these coated systems. Within this context, the influence of surface integrity changes caused by abrasive grinding of the hardmetal substrate, prior to coating, is evaluated with respect to contact damage resistance. Three different substrate surface finish conditions are studied: ground (G), mirror-like polished (P) and ground plus heat-treated (GTT). Tests are conducted by means of spherical indentation under increasing monotonic load and the contact damage resistance is assessed. Substrate grinding enhances resistance against both crack nucleation at the coating surface and subsequent propagation into the hardmetal substrate. Hence, crack emergence and damage evolution is effectively delayed for the coated G condition, as compared to the reference P one. The observed system response is discussed on the basis of the beneficial effects associated with compressive residual stresses remnant at the subsurface level after grinding, ion-etching and coating. The influence of the stress state is further corroborated by the lower contact damage resistance exhibited by the coated GTT specimens. Finally, differences observed on the interaction between indentation-induced damage and failure mode under flexural testing points in the direction that substrate grinding also enhances damage tolerance of the coated system when exposed to contact loads.
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| 22. |
- Yang, Jie, et al.
(author)
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Implementation of advanced characterisation techniques for assessment of grinding effects on the surface integrity of WC-Co cemented carbides
- 2018
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In: Powder Metallurgy. - : Taylor & Francis. - 0032-5899 .- 1743-2901. ; 61:2, s. 100-105
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Journal article (peer-reviewed)abstract
- Grinding is a key step on the manufacturing process of WC-Co cemented carbides (hardmetals). In this work, an investigation of grinding effects on the surface integrity of hardmetals is conducted. It is done by combining diverse advanced characterisation techniques: X-ray diffraction, field emission-scanning electron microscopy, electron back scatter diffraction, focused ion beam - 3D tomography and transmission electron microscopy. The study is carried out in a fine-grained WC-Co grade. Besides ground state, polished surface finish condition is assessed for comparison purposes. It is evidenced that grinding induces significant alterations: 3D tomography illustrates microcracking exists down to 2.5 mu m depth with a highly anisotropic distribution at the subsurface, large compressive residual stresses extending until subsurface levels of about 12 mu m, and phase transformation of binder from the original fcc phase into the hcp one, as well as severe plastic deformation observed within the binder at the surface level.
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| 23. |
- Yang, J., et al.
(author)
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Substrate surface finish effects on scratch resistance and failure mechanisms of TiN-coated hardmetals
- 2015
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In: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 265, s. 174-184
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Journal article (peer-reviewed)abstract
- In this study, the influence of substrate surface finish on scratch resistance and associated failure mechanisms is investigated in the case of a TiN-coated hardmetal. Three different surface finish conditions are studied: as-sintered (AS), ground (G), and mirror-like polished (P). For G conditioned samples, scratch tests are conducted both parallel and perpendicular to the direction of the grinding grooves. It is found that coated AS, G and P samples exhibit similar critical load for initial substrate exposure and the same brittle adhesive failure mode. However, the damage scenarios are different, i.e. the substrate exposure is discrete and localized to the scratch tracks for G samples while a more pronounced and continuous exposure is seen for AS and P ones. Aiming to understand the role played by the grinding-induced compressive residual stresses, the study is extended to coated systems where ground substrates are thermal annealed (for relieving stresses) before being ion etched and coated. It yielded lower critical loads and changes in the mechanisms for the scratch-related failure; the latter depending on the relative orientation between scratching and grinding directions. (C) 2015 Elsevier B.V. All rights reserved.
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| 24. |
- Zhu, Jianqiang, et al.
(author)
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Effects of cathode grain size and substrate fixturing on the microstructure evolution of arc evaporated Cr-cathodes and Cr-N coating synthesis
- 2014
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In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 32:2, s. 021515-
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Journal article (peer-reviewed)abstract
- The influence of the cathode grain size and the substrate fixturing on the microstructure evolution of the Cr cathodes and the resulting Cr-N coating synthesis is studied. Hot isostatic pressed Cr cathodes with three different grain sizes were arc evaporated in a nitrogen atmosphere and Cr-N coatings were deposited on cemented carbide substrate at 2 and 4 Pa nitrogen pressure, respectively. The Cr cathodes before and after arc discharging are composed of polycrystalline α-Cr regardless of the grain size. A converted layer forms on the Cr cathode surface and its microstructure differs with the cathode grain size. A stationary substrate fixturing results in ditches covering the cathode surface while a single rotating fixturing does not. The increased grain size of the virgin Cr cathodes enhances the quantities of the ditches. The possible causes are addressed. At 2 Pa nitrogen pressure, the Cr-N coatings deposited with the single rotating fixturing comprise only cubic CrN phase while the ones deposited with the stationary fixturing contain a mixture of hexagonal Cr2N and cubic CrN phases. By the increasing grain size of the Cr cathode, the droplet density of the Cr-N coatings increase somewhat while the hardness decreases for the Cr-N coatings deposited with stationary fixturing at 2 Pa nitrogen pressure.
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| 25. |
- Zhu, Jianqiang, et al.
(author)
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Influence of Ti-Si cathode grain size on the cathodic arc process and resulting Ti-Si-N coatings
- 2013
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In: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 235:25, s. 637-647
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Journal article (peer-reviewed)abstract
- The influence of the Ti-Si cathode grain size on cathodic arc processes and resulting Ti-Si-N coating synthesis has been studied. 63 mm Ti-Si cathodes containing 20-25 at % Si with four dedicated grain size of ~8 µm, ~20 µm, ~110 µm, and ~600 µm were fabricated via spark plasma sintering or hot isostatic pressing. They were evaporated in 2 Pa nitrogen atmosphere in an industrial-scale arc deposition system and the Ti-Si-N coatings were grown at 50 A, 70 A, and 90 A arc current. The composition and microstructure of the virgin and worn cathode surfaces as well as the resulting coatings were characterized using optical and electron microscopy, x-ray diffraction, elastic recoil detection analysis, x-ray photoelectron spectroscopy, and nanoindentation. The results show that the existence of multiple phases with different work function values directly influences the cathode spot ignition behavior and also the arc movement and appearance. Specifically, there is a preferential erosion of the Ti5Si3-phase grains. By increasing the grain size of the virgin cathode, the preferential erosion is enhanced, such that the cathode surface morphology roughens substantially after 600 Ah arc discharging. The deposition rate of the Ti-Si-N coating is increased with decreasing grain size of the evaporated Ti-Si cathodes. The composition, droplet density, and droplet shape of the coatings are influenced by the arc movement, which is also shown to depend on the cathode grain size.
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