In this work was shown the high stability of the single-phase structural state of high entropy alloy of
Ti-V-Zr-Nb-Hf system in a vacuum-arc method of obtaining of coatings based on it. In the process of deposition
single-phase high entropy coatings with bcc-lattice which characterizes the cast state are formed in
vacuum, and upon obtaining in a nitrogen atmosphere single-phase nitride superhard coatings based
on fcc-metal lattice are formed. Such a stability of structure of multi-element alloy to high temperature
evaporation and deposition from high-energy plasma flows allows to use the techniques developed for
simple substitution phases in the analysis of their structural-stress state.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3480

Andreev, A.A.

Gorban, V.

Sobol, O.V.

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 1 No 2, 02NFC03(2pp) (2012)   2304-1862/2012/1(2)02NFC03(2) 02NFC03-1  2012 Sumy State University Structural-Strained State and Mechanical Characteristics of Single-Phase Vacuum-Arc  Coatings of Multicomponent High Entropy System Ti-V-Zr-Nb-Hf and Nitrides Based On It   O.V. Sobol`1,*, A. A. Andreev2,†, V.F. Gorban`3,‡, N.А. Krapivka3, V.А. Stolbovoy2, V.Ye. Fil`chikov1, S.А. Firstov3  1 National Technical University “KhPI”, 21, Frunze St., 61002, Kharkov, Ukraine  2 National Scientific Centre «KhPTI», 1, Akademicheskaya St., 61108, Kharkov, Ukraine  3 Institute for problems of materials science NAS of Ukraine, 3, Krzhizhanovsky str., 03680,  Kyiv, Ukraine  (Received 13 March 2012; published online16 August 2012)  In this work was shown the high stability of the single-phase structural state of high entropy alloy of Ti-V-Zr-Nb-Hf system in a vacuum-arc method of obtaining of coatings based on it. In the process of depo-sition single-phase high entropy coatings with bcc-lattice which characterizes the cast state are formed in vacuum, and upon obtaining in a nitrogen atmosphere single-phase nitride superhard coatings based on fcc-metal lattice are formed. Such a stability of structure of multi-element alloy to high tempera-ture evaporation and deposition from high-energy plasma flows allows to use the techniques developed for simple substitution phases in the analysis of their structural-stress state.   Keywords: Vacuum-arc coating, High entropy alloy, Single-phase structural state, Nitride, Superhard.   PACS numbers: 81.07.Bc , 61.05.cf ; 62.25. – g ______________ * sool@kpi.kharkov.ua † aandreev@kipt.kharkov.ua ‡ gvf@ipms.kiev.ua   1. INTRODUCTION   To increase the thermal stability of the material the concept of multi-component high entropy alloys (HEA) (see, eg [1-5]) was proposed and experimentally proved. In this paper, five-element alloy of vaporized cathode consisted two elements (Nb and V) which have bcc-lattice at room temperature and form a continuous series of sol-id solutions, as well as Hf, Zr. and Ti, which also form a continuous solid solutions with each other and have hex-agonal (hcp) crystal lattice at room temperature, but with bcc-lattice at high temperatures. Simultaneously, Hf, Zr, Nb and V are -stabilizers for titanium.  In such a combination of both stabilizing bcc-lattice V and Nb, and the refractory components of Hf, Zr, and Ti, because of its high affinity to nitrogen [6] define the possibility of formation of nitride phase on the basis of high entropy one-component alloy.  2. METHODS OF SAMPIE MANUFACTURING AND ANALYSIS   The cathodes of the high entropy alloys Ti-V-Zr-Nb-Hf were prepared by vacuum-arc melting in an atmos-phere of high purity argon. Preparation of coatings was carried out by vacuum-arc evaporation of the cathode at the "Bulat-6" plant when applying a constant nega-tive bias of the substrate Ub  (–40 ... –200) V, arc cur-rent 85 A. residual gas pressure of 0.0066 Pa, the pres-sures of nitrogen (0.04 ... 0.66) Pa. The deposition rate was about 1.5 nm/ s. The study of structural-stress state was carried out on DRON-3M diffractometer in the emission of Cu-Kα. Microindentation were carried out on the "Micron-Gamma" plant [7] under a load of up to F  0.5 N Berkovich diamond pyramid with an angle of 65 . 3. RESULTS AND DISCUSSION   Vacuum-arc evaporation of cathodes of high entropy Ti-V-Zr-Nb-Hf bcc-system with content of elements close to the equiatomic in vacuum (residual atmosphere pressure 0.0066 Pa) led to the formation of coatings with preserved single-phase, i.e. with bcc-lattice and a strong texture with the axis [ 110] parallel to the direc-tion of the fall of film-forming particles. On the X-ray diffraction spectrum (Fig. 1, spectrum 1) in the condi-tion of focusing Bragg-Brentano ( -2  -scheme) appear only reflections of two orders of reflection from the {110} planes. The average size of crystallites in the di-rection of the texture is 80 nm at a thickness of the coating of more than 7 um. In the case of deposition of coatings in the presence of a nitrogen atmosphere at the lowest of the pressures used in the work PN  0.04 Pa there is the formation of non-textured polycrystaliine single-phase state (fcc-lattice), even when applying high Ub  –200 V (see Fig. 1). Size of crystallites vary from 35 nm at Ub  –100 V to 50 nm at Ub  –200 V. The increase in pressure (PN  0.11 Pa) leads to the formation of textured single-phase fcc-coatings. When Ub  –50 V –100 V there is a transition from a partly textured state with the [111] axis perpendicular to the plane of growth to the state with a nearly uniaxial tex-ture with the axis [111]. When Ub  –200 V bitextured state with axes [111] and [110] is formed perpendicular to the plane of growth. The appearance of the latter type of the axis of texture is determined by minimiza-tion of the radiation factor influence while the deposi-tion and for pure TiN coatings is usually observed for large values of Ub > –400V [8]. The appearance of this type of texture with lesser Ub than for pure TiN can be associated with a high content of Hf (17 ... 25 at.%) in  O.V. SOBOL, A. A. ANDREEV, V.F. GORBAN, ET AL. PROC. NAP 1, 02NFC03 (2012)   02NFC03-2 the coating. Crystallite size varies from 47 nm to 95 nm with increasing Ub. The hardness of coatings obtained at this pressure is sufficiently high and is (40 ... 50) GPa.    Fig. 1 – Plots of the diffraction spectra of vacuum-arc coating system of high entropy system Ti-V-Zr-Nb-Hf, obtained: 1 - in the absence of atmospheric nitrogen (H  8.2 GPa, E*  105 GPa) and PN  0.27 Pa and Ub: 2 - –50 V (H  59 GPa, E*  401 GPa), 3 - –100 V (H  64 GPa, E*  436 GPa) and 4 - –200 V (H  70 GPa, E*  429 GPa)  Nitride coatings showed the highest hardness ob-tained on the basis high entropy alloys under pressure PN  0.27 Pa. At this pressure with increasing of Ub structural changes similar to those in coatings deposit-ed at PN  0.11 Pa were observed. The appearance of the texture [111] and its growing perfection at Ub  –50 V and Ub  –100 V respectively (Fig. 1), leads to in-crease in hardness of coating from 59 GPa up to 64 GPa, and the appearance of biaxial texture with axes [ 111] and [110] at Ub  –200 V leads to the high-est hardness of 70 GPa. The size of the crystallites in this case is 57 nm. Note that the coatings generated when Ub  –200 V have a very homogeneous smooth surface. The analysis of the deformed state of nitride high entropy coatings according to "a - sin2 »-graphs showed that in the case of biaxial texture, lattice de-formation in the crystallites with the texture axis [110] exceed the deformation in the group with the axis [111]. The greatest compression deformation is ob-served in the crystallites of coatings obtained with the maximum Ub  –200 V, and reaches in the case of PN  0.27 Pa value –1.79% and –3.7% for groups of crystallites with the axes [111] and [110], respectively. For a lower PN  0.11 Pa the value of deformation is somewhat lower and has a value of –1.7% and –3.45% respectively. In the areas bordering the substrate (at a depth of 1 um from the substrate), there is less defor-mation (by up to 20%).The reason for this is apparently a partial relaxation of the deformation by means of the substrate (stainless steel 12X18H9T) flow in the border region [9]. In the case of the high brittleness of the sub-strate (monocrystal Si plate, thickness of 380 um) high stress-strain state of compression in the coating leads to the destruction of the substrate. By lowering the Ub to –50 V the magnitude of the compressive strain of the lattice does not exceed the absolute value of 2%. Thus, when the state of uniaxial texture, the hardness of ni-tride coatings based on high entropy alloys does not exceed 60 GPa, and the higher the hardness is achieved in the case of formation of biaxial texture with axes [111] and [110], which is observed when Ub  –200 V in alloys with relatively high content of Hf.   REFERENCES  1. V. Dolique, A-L. Thomann, P. Brault, Y. Tessier, P. Gillon, Mat. Chem. Phys. 117, 142 (2009.). 2. V. Dolique, A-L. Thomann, P. Brault, Y. Tessier, P. Gillon, Surf. Coat. Tech. 204, 1989 (2010). 3. M. Tsai, C. Wang, C. Tsai, W. Shen, J. Yeh, J. Gan, W. Wu, J. Electr. Soc. 158, H1161 (2011). 4. S. Ranganathan, Curr. Sci. 85, 1404 (2003). 5. A. Li, X. Zhang, Acta Metall. Sin. (Engl. Lett.) 22, 219 (2009). 6. O.V. Sobol, A.A. Andreyev, S.N. Grigoryev, V.F. Gorban, V.A. Stolbovoy, I.V. Serduk, V.E. Filchikov, West.-Europ. Mag. Tech., 6/5(54), 4 (2011). 7. E. Aznakayev, Proceedings of the International Conference “Small Talk, TP.001, 8 (2003). 8. N.A. Azarenkov, O.V. Sobol, A.D. Pogrebnyak, V.M. Beresnev, Vacuum-plasma surface ingeneering (Kharkiv, Karazin KhNU: 2011). 9. O.V. Sobol, A.A. Andreyev, V.A. Stolbovoy, V.E. Filchikov, Tech. Phys. Lett. 38, 26 (2012).  

Structural-Strained State and Mechanical Characteristics of Single-Phase Vacuum-Arc Coatings of Multicomponent High Entropy System Ti-V-Zr-Nb-Hf and Nitrides Based On It

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 1 No 2, 02NFC03(2pp) (2012) 
 
 
2304-1862/2012/1(2)02NFC03(2) 02NFC03-1  2012 Sumy State University 
Structural-Strained State and Mechanical Characteristics of Single-Phase Vacuum-Arc  
Coatings of Multicomponent High Entropy System Ti-V-Zr-Nb-Hf and Nitrides Based On It 
 
 O.V. Sobol`1,*, A. A. Andreev2,†, V.F. Gorban`3,‡, N.А. Krapivka3, V.А. Stolbovoy2, 
V.Ye. Fil`chikov1, S.А. Firstov3 
 
1 National Technical University “KhPI”, 21, Frunze St., 61002, Kharkov, Ukraine  
2 National Scientific Centre «KhPTI», 1, Akademicheskaya St., 61108, Kharkov, Ukraine  
3 Institute for problems of materials science NAS of Ukraine, 3, Krzhizhanovsky str., 03680,  Kyiv, Ukraine 
 
(Received 13 March 2012; published online16 August 2012) 
 
In this work was shown the high stability of the single-phase structural state of high entropy alloy of 
Ti-V-Zr-Nb-Hf system in a vacuum-arc method of obtaining of coatings based on it. In the process of depo-
sition single-phase high entropy coatings with bcc-lattice which characterizes the cast state are formed in 
vacuum, and upon obtaining in a nitrogen atmosphere single-phase nitride superhard coatings based 
on fcc-metal lattice are formed. Such a stability of structure of multi-element alloy to high tempera-
ture evaporation and deposition from high-energy plasma flows allows to use the techniques developed for 
simple substitution phases in the analysis of their structural-stress state.  
 
Keywords: Vacuum-arc coating, High entropy alloy, Single-phase structural state, Nitride, Superhard. 
 
 PACS numbers: 81.07.Bc , 61.05.cf ; 62.25. – g 
______________ 
* sool@kpi.kharkov.ua 
† aandreev@kipt.kharkov.ua 
‡ gvf@ipms.kiev.ua 
 
 
1. INTRODUCTION 
 
 To increase the thermal stability of the material the 
concept of multi-component high entropy alloys (HEA) 
(see, eg [1-5]) was proposed and experimentally proved. 
In this paper, five-element alloy of vaporized cathode 
consisted two elements (Nb and V) which have bcc-lattice 
at room temperature and form a continuous series of sol-
id solutions, as well as Hf, Zr. and Ti, which also form a 
continuous solid solutions with each other and have hex-
agonal (hcp) crystal lattice at room temperature, but with 
bcc-lattice at high temperatures. Simultaneously, Hf, Zr, 
Nb and V are -stabilizers for titanium. 
 In such a combination of both stabilizing bcc-lattice 
V and Nb, and the refractory components of Hf, Zr, and 
Ti, because of its high affinity to nitrogen [6] define the 
possibility of formation of nitride phase on the basis of 
high entropy one-component alloy. 
 
2. METHODS OF SAMPIE MANUFACTURING 
AND ANALYSIS 
 
 The cathodes of the high entropy alloys Ti-V-Zr-Nb-
Hf were prepared by vacuum-arc melting in an atmos-
phere of high purity argon. Preparation of coatings was 
carried out by vacuum-arc evaporation of the cathode 
at the "Bulat-6" plant when applying a constant nega-
tive bias of the substrate Ub  (–40 ... –200) V, arc cur-
rent 85 A. residual gas pressure of 0.0066 Pa, the pres-
sures of nitrogen (0.04 ... 0.66) Pa. The deposition rate 
was about 1.5 nm/ s. 
The study of structural-stress state was carried out 
on DRON-3M diffractometer in the emission of Cu-Kα. 
Microindentation were carried out on the "Micron-
Gamma" plant [7] under a load of up to F  0.5 N 
Berkovich diamond pyramid with an angle of 65 . 
3. RESULTS AND DISCUSSION  
 
Vacuum-arc evaporation of cathodes of high entropy 
Ti-V-Zr-Nb-Hf bcc-system with content of elements 
close to the equiatomic in vacuum (residual atmosphere 
pressure 0.0066 Pa) led to the formation of coatings 
with preserved single-phase, i.e. with bcc-lattice and a 
strong texture with the axis [ 110] parallel to the direc-
tion of the fall of film-forming particles. On the X-ray 
diffraction spectrum (Fig. 1, spectrum 1) in the condi-
tion of focusing Bragg-Brentano ( -2  -scheme) appear 
only reflections of two orders of reflection from the 
{110} planes. The average size of crystallites in the di-
rection of the texture is 80 nm at a thickness of the 
coating of more than 7 um. 
In the case of deposition of coatings in the presence 
of a nitrogen atmosphere at the lowest of the pressures 
used in the work PN  0.04 Pa there is the formation of 
non-textured polycrystaliine single-phase state (fcc-
lattice), even when applying high Ub  –200 V (see Fig. 
1). Size of crystallites vary from 35 nm at Ub  –100 V 
to 50 nm at Ub  –200 V. 
The increase in pressure (PN  0.11 Pa) leads to the 
formation of textured single-phase fcc-coatings. When 
Ub  –50 V –100 V there is a transition from a partly 
textured state with the [111] axis perpendicular to the 
plane of growth to the state with a nearly uniaxial tex-
ture with the axis [111]. When Ub  –200 V bitextured 
state with axes [111] and [110] is formed perpendicular 
to the plane of growth. The appearance of the latter 
type of the axis of texture is determined by minimiza-
tion of the radiation factor influence while the deposi-
tion and for pure TiN coatings is usually observed for 
large values of Ub > –400V [8]. The appearance of this 
type of texture with lesser Ub than for pure TiN can be 
associated with a high content of Hf (17 ... 25 at.%) in 
 O.V. SOBOL, A. A. ANDREEV, V.F. GORBAN, ET AL. PROC. NAP 1, 02NFC03 (2012) 
 
 
02NFC03-2 
the coating. Crystallite size varies from 47 nm to 95 nm 
with increasing Ub. The hardness of coatings obtained 
at this pressure is sufficiently high and is (40 ... 
50) GPa. 
 
 
 
Fig. 1 – Plots of the diffraction spectra of vacuum-arc coating 
system of high entropy system Ti-V-Zr-Nb-Hf, obtained: 1 - in 
the absence of atmospheric nitrogen (H  8.2 GPa, 
E*  105 GPa) and PN  0.27 Pa and Ub: 2 - –50 V (H  59 GPa, 
E*  401 GPa), 3 - –100 V (H  64 GPa, E*  436 GPa) and 4 -
 –200 V (H  70 GPa, E*  429 GPa) 
 
Nitride coatings showed the highest hardness ob-
tained on the basis high entropy alloys under pressure 
PN  0.27 Pa. At this pressure with increasing of Ub 
structural changes similar to those in coatings deposit-
ed at PN  0.11 Pa were observed. The appearance of 
the texture [111] and its growing perfection at Ub  –
50 V and Ub  –100 V respectively (Fig. 1), leads to in-
crease in hardness of coating from 59 GPa up to 
64 GPa, and the appearance of biaxial texture with 
axes [ 111] and [110] at Ub  –200 V leads to the high-
est hardness of 70 GPa. The size of the crystallites in 
this case is 57 nm. Note that the coatings generated 
when Ub  –200 V have a very homogeneous smooth 
surface. 
The analysis of the deformed state of nitride high 
entropy coatings according to "a - sin2 »-graphs 
showed that in the case of biaxial texture, lattice de-
formation in the crystallites with the texture axis [110] 
exceed the deformation in the group with the axis 
[111]. The greatest compression deformation is ob-
served in the crystallites of coatings obtained with the 
maximum Ub  –200 V, and reaches in the case of 
PN  0.27 Pa value –1.79% and –3.7% for groups of 
crystallites with the axes [111] and [110], respectively. 
For a lower PN  0.11 Pa the value of deformation is 
somewhat lower and has a value of –1.7% and –3.45% 
respectively. In the areas bordering the substrate (at a 
depth of 1 um from the substrate), there is less defor-
mation (by up to 20%).The reason for this is apparently 
a partial relaxation of the deformation by means of the 
substrate (stainless steel 12X18H9T) flow in the border 
region [9]. In the case of the high brittleness of the sub-
strate (monocrystal Si plate, thickness of 380 um) high 
stress-strain state of compression in the coating leads 
to the destruction of the substrate. By lowering the Ub 
to –50 V the magnitude of the compressive strain of the 
lattice does not exceed the absolute value of 2%. Thus, 
when the state of uniaxial texture, the hardness of ni-
tride coatings based on high entropy alloys does not 
exceed 60 GPa, and the higher the hardness is achieved 
in the case of formation of biaxial texture with axes 
[111] and [110], which is observed when Ub  –200 V in 
alloys with relatively high content of Hf.  
 
REFERENCES 
 
1. V. Dolique, A-L. Thomann, P. Brault, Y. Tessier, P. Gillon, 
Mat. Chem. Phys. 117, 142 (2009.). 
2. V. Dolique, A-L. Thomann, P. Brault, Y. Tessier, P. Gillon, 
Surf. Coat. Tech. 204, 1989 (2010). 
3. M. Tsai, C. Wang, C. Tsai, W. Shen, J. Yeh, J. Gan, 
W. Wu, J. Electr. Soc. 158, H1161 (2011). 
4. S. Ranganathan, Curr. Sci. 85, 1404 (2003). 
5. A. Li, X. Zhang, Acta Metall. Sin. (Engl. Lett.) 22, 219 
(2009). 
6. O.V. Sobol, A.A. Andreyev, S.N. Grigoryev, V.F. Gorban, 
V.A. Stolbovoy, I.V. Serduk, V.E. Filchikov, West.-Europ. 
Mag. Tech., 6/5(54), 4 (2011). 
7. E. Aznakayev, Proceedings of the International Conference 
“Small Talk, TP.001, 8 (2003). 
8. N.A. Azarenkov, O.V. Sobol, A.D. Pogrebnyak, 
V.M. Beresnev, Vacuum-plasma surface ingeneering 
(Kharkiv, Karazin KhNU: 2011). 
9. O.V. Sobol, A.A. Andreyev, V.A. Stolbovoy, V.E. Filchikov, 
Tech. Phys. Lett. 38, 26 (2012). 
 


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Structural-Strained State and Mechanical Characteristics of Single-Phase Vacuum-Arc Coatings of Multicomponent High Entropy System Ti-V-Zr-Nb-Hf and Nitrides Based On It

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