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Influence of Zr on structure, mechanical and thermal properties of Ti-Al-N.

Chen L, Holec D, Du Y, Mayrhofer PH - Thin Solid Films (2011)

Bottom Line: Here, we study the effect of Zr addition on structure, mechanical and thermal properties of Ti(1-x)Al(x)N based coatings under the guidance of ab initio calculations.Increasing the Zr content from z = 0 to 0.17, while keeping x at ~ 0.5, results in a hardness increase from ~ 33 to 37 GPa, and a lattice parameter increase from 4.18 to 4.29 Å.Furthermore, Zr assists the formation of a dense oxide scale.

View Article: PubMed Central - PubMed

Affiliation: Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Leoben, 8700, Austria.

ABSTRACT
Multinary Ti-Al-N thin films are used for various applications where hard, wear and oxidation resistant materials are needed. Here, we study the effect of Zr addition on structure, mechanical and thermal properties of Ti(1-x)Al(x)N based coatings under the guidance of ab initio calculations. The preparation of Ti(1-x-z)Al(x)Zr(z)N by magnetron sputtering verifies the suggested cubic (NaCl-type) structure for x below 0.6-0.7 and z ≤ 0.4. Increasing the Zr content from z = 0 to 0.17, while keeping x at ~ 0.5, results in a hardness increase from ~ 33 to 37 GPa, and a lattice parameter increase from 4.18 to 4.29 Å. The latter are in excellent agreement with ab initio data. Alloying with Zr also promotes the formation of cubic domains but retards the formation of stable wurtzite AlN during thermal annealing. This leads to high hardness values of ~ 40 GPa over a broad temperature range of 700-1100 °C for Ti(0.40)Al(0.55)Zr(0.05)N. Furthermore, Zr assists the formation of a dense oxide scale. After 20 h exposure in air at 950 °C, where Ti(0.48)Al(0.52)N is already completely oxidized, only a ~ 1 μm thin oxide scale is formed on top of the otherwise still intact ~ 2.5 μm thin film Ti(0.40)Al(0.55)Zr(0.05)N.

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XRD patterns after annealing in vacuum to temperatures Ta up to 1500 °C of (a) Ti0.48Al0.52N, (b) Ti0.40Al0.55Zr0.05N, and (c) Ti0.39Al0.51Zr0.10N.
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f0025: XRD patterns after annealing in vacuum to temperatures Ta up to 1500 °C of (a) Ti0.48Al0.52N, (b) Ti0.40Al0.55Zr0.05N, and (c) Ti0.39Al0.51Zr0.10N.

Mentions: Fig. 5 shows the structural evolution during annealing of our Ti0.48Al0.52N (a) Ti0.4Al0.55Zr0.05N (b) and Ti0.39Al0.51Zr0.1N (c) films by means of XRD patterns after annealing to 700, 850, 1100, 1200, and 1500 °C. The Zr-free Ti0.48Al0.52N film exhibits a small shift of the XRD peaks during annealing to 700 °C as compared with the as deposited state, see Fig. 5a, suggesting only minute structural changes like recovery and relaxation which contribute to the exothermic DSC feature in this temperature range. The XRD patterns of the Zr-containing films Ti0.4Al0.55Zr0.05N and Ti0.39Al0.51Zr0.1N annealed to 700 °C reveal also a shift in the peak position to higher diffraction angles but also an increase in peak broadening, see Fig. 5b and c. The latter is an indication for a reduction in grain size and/or an increase in microstresses which can result from the onset of a decomposition process [14,20]. This can better be seen after annealing at 850 °C, where the XRD peaks exhibit on both sides (lower and higher diffraction angles) an increase in intensity and width, suggesting the formation of Al-depleted and Al-enriched domains. After annealing at 1100 °C, a pronounced shoulder-formation on both sides of the ‘matrix’ XRD peak can be seen clearly. These shoulders indicate the formation of TiN- and AlN-rich cubic domains for Ti0.48Al0.52N, and TiN-, ZrN- and AlN-rich cubic domains for the Zr-containing films. While the Zr-free film, Ti0.48Al0.52N, exhibits the formation of w-AlN already after annealing at 1100 °C, no w-AlN formation can be detected for the Zr-containing films (compare Fig. 5a, b, and c), indicating that Zr effectively retards the formation of w-AlN. After annealing at 1200 °C, almost no intensity at the XRD peak positions of as deposited films can be detected, indicating close-to-complete decomposition of the original supersaturated matrix. The Ti0.48Al0.52N film is mainly composed of TiN- and AlN-rich cubic phases and w-AlN, whereas it is still hard to detect any w-AlN for the Zr containing films, Ti0.4Al0.55Zr0.05N and Ti0.39Al0.51Zr0.1N, which at this stage compose mainly of ZrN-, TiN- and AlN-rich cubic phases.


Influence of Zr on structure, mechanical and thermal properties of Ti-Al-N.

Chen L, Holec D, Du Y, Mayrhofer PH - Thin Solid Films (2011)

XRD patterns after annealing in vacuum to temperatures Ta up to 1500 °C of (a) Ti0.48Al0.52N, (b) Ti0.40Al0.55Zr0.05N, and (c) Ti0.39Al0.51Zr0.10N.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3117144&req=5

f0025: XRD patterns after annealing in vacuum to temperatures Ta up to 1500 °C of (a) Ti0.48Al0.52N, (b) Ti0.40Al0.55Zr0.05N, and (c) Ti0.39Al0.51Zr0.10N.
Mentions: Fig. 5 shows the structural evolution during annealing of our Ti0.48Al0.52N (a) Ti0.4Al0.55Zr0.05N (b) and Ti0.39Al0.51Zr0.1N (c) films by means of XRD patterns after annealing to 700, 850, 1100, 1200, and 1500 °C. The Zr-free Ti0.48Al0.52N film exhibits a small shift of the XRD peaks during annealing to 700 °C as compared with the as deposited state, see Fig. 5a, suggesting only minute structural changes like recovery and relaxation which contribute to the exothermic DSC feature in this temperature range. The XRD patterns of the Zr-containing films Ti0.4Al0.55Zr0.05N and Ti0.39Al0.51Zr0.1N annealed to 700 °C reveal also a shift in the peak position to higher diffraction angles but also an increase in peak broadening, see Fig. 5b and c. The latter is an indication for a reduction in grain size and/or an increase in microstresses which can result from the onset of a decomposition process [14,20]. This can better be seen after annealing at 850 °C, where the XRD peaks exhibit on both sides (lower and higher diffraction angles) an increase in intensity and width, suggesting the formation of Al-depleted and Al-enriched domains. After annealing at 1100 °C, a pronounced shoulder-formation on both sides of the ‘matrix’ XRD peak can be seen clearly. These shoulders indicate the formation of TiN- and AlN-rich cubic domains for Ti0.48Al0.52N, and TiN-, ZrN- and AlN-rich cubic domains for the Zr-containing films. While the Zr-free film, Ti0.48Al0.52N, exhibits the formation of w-AlN already after annealing at 1100 °C, no w-AlN formation can be detected for the Zr-containing films (compare Fig. 5a, b, and c), indicating that Zr effectively retards the formation of w-AlN. After annealing at 1200 °C, almost no intensity at the XRD peak positions of as deposited films can be detected, indicating close-to-complete decomposition of the original supersaturated matrix. The Ti0.48Al0.52N film is mainly composed of TiN- and AlN-rich cubic phases and w-AlN, whereas it is still hard to detect any w-AlN for the Zr containing films, Ti0.4Al0.55Zr0.05N and Ti0.39Al0.51Zr0.1N, which at this stage compose mainly of ZrN-, TiN- and AlN-rich cubic phases.

Bottom Line: Here, we study the effect of Zr addition on structure, mechanical and thermal properties of Ti(1-x)Al(x)N based coatings under the guidance of ab initio calculations.Increasing the Zr content from z = 0 to 0.17, while keeping x at ~ 0.5, results in a hardness increase from ~ 33 to 37 GPa, and a lattice parameter increase from 4.18 to 4.29 Å.Furthermore, Zr assists the formation of a dense oxide scale.

View Article: PubMed Central - PubMed

Affiliation: Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Leoben, 8700, Austria.

ABSTRACT
Multinary Ti-Al-N thin films are used for various applications where hard, wear and oxidation resistant materials are needed. Here, we study the effect of Zr addition on structure, mechanical and thermal properties of Ti(1-x)Al(x)N based coatings under the guidance of ab initio calculations. The preparation of Ti(1-x-z)Al(x)Zr(z)N by magnetron sputtering verifies the suggested cubic (NaCl-type) structure for x below 0.6-0.7 and z ≤ 0.4. Increasing the Zr content from z = 0 to 0.17, while keeping x at ~ 0.5, results in a hardness increase from ~ 33 to 37 GPa, and a lattice parameter increase from 4.18 to 4.29 Å. The latter are in excellent agreement with ab initio data. Alloying with Zr also promotes the formation of cubic domains but retards the formation of stable wurtzite AlN during thermal annealing. This leads to high hardness values of ~ 40 GPa over a broad temperature range of 700-1100 °C for Ti(0.40)Al(0.55)Zr(0.05)N. Furthermore, Zr assists the formation of a dense oxide scale. After 20 h exposure in air at 950 °C, where Ti(0.48)Al(0.52)N is already completely oxidized, only a ~ 1 μm thin oxide scale is formed on top of the otherwise still intact ~ 2.5 μm thin film Ti(0.40)Al(0.55)Zr(0.05)N.

No MeSH data available.


Related in: MedlinePlus