The elemental and structural features of the nitride nanostructured coating produced by vacuum arc evaporation from high-entropy cathode TiHfVNbZr were studied. Using of the complementary methods of elemental analysis (RBS, SIMS and GDMS) allowed to carry out a comprehensive analysis of the elemental composition, namely to determine the chemical composition of the surface layer, to establish the characteristics of the distribution of elements in depth and to identify uncontrollable impurities

Bahdasarian, Artem Anatoliiovych

Bilokur, M.O

Багдасарян, Артем Анатольевич

Багдасарян, Артем Анатолійович

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  
NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 3 No 1, 01NTF19(5pp) (2014) 
 
 
2304-1862/2014/3(1)01NTF19(5) 01NTF19-1  2014 Sumy State University 
Analysis of Morphology and Elemental Composition of   
(Ti-Zr-Hf-V-Nb)N High-entropy Alloys 
 
A.A. Bagdasaryan, M.O. Bilokur* 
 
Sumy State University, 2, Rimsky-Korsakov Str., 40007 Sumy, Ukraine 
 
(Received 16 July 2014; published online 29 August 2014) 
 
(Ti-Hf-V-Nb-Zr)N nanocomposite coating obtained by vacuum arc deposition method was investigated. 
Such techniques as Rutherford backscattering spectrometry (RBS), Secondary ion mass spectrometry 
(SIMS) and Glow Discharge Mass Spectrometry (GDMS) were used to conduct analysis of the structure of 
the coating, elemental distribution and composition of the elements. 
 
Keywords: High-entropy alloy, Nitride coating, Depth profiles, Elemental composition, Ion beam technique. 
 
 PACS numbers: 81.05.Je, 81.70.Jb 
 
 
                                                                
* Maryna.Bilokur@gmail.com 
1. INTRODUCTION 
 
Recently, Yeh et al. developed a new class of metal 
compounds; so-called high-entropy alloys [11-16]. The 
concept of such alloys assumes at least 5 principal ele-
ments and the formation of the stable single-phase sol-
id solution. The high entropy of mixing can stabilize the 
formation of a single-phase solid solution and prevent 
the formation of intermetallic compound during solidi-
fication. These alloys can possess various outstanding 
properties such as high hardness along with good duc-
tility and durability, good wear resistance, good corro-
sion resistance and etc [17-22]. The nitride coatings of 
the high-entropy alloys are often used as the diffusion 
barriers in interconnects due to presumably high diffu-
sion resistance [22-25]. 
In addition, the serious lattice distortions caused by 
the different sizes of atoms of the constituent elements 
decrease the coefficient of diffusion of the atoms, there-
by reducing the growth of crystallites. Therefore, as it 
was previously shown from [26, 27], high-entropy alloys 
tend to form nanosize structures. As it is known from 
[28-34], the size reduction down to nanometer scale 
leads to significant changes in physical and mechanical 
properties. In turn, the structure and state of the grain 
boundaries are also important in the nanocrystalline 
materials. Thus, the preparation of new materials of 
nanocomposite coatings of the (Ti-Hf-Zr-V-Nb)N basis 
using the cathodic-arc-vapor deposition method and the 
investigation of their physical-mechanical properties is 
an actual problem of modern materials science. 
The purpose of this work is to  analyze distribution 
of elements and contaminations in the films, using the 
complementary methods of elemental analysis. 
 
2. EXPERIMENTAL 
 
The cathodes of high-entropy alloy TiHfVNbZr were 
prepared by vacuum arc melting in an atmosphere of 
high purity argon. The melting was performed using a 
nonconsumable tungsten electrode into a copper water-
cooled crucible. Repeating melting for at least 7 times 
with a cooling rate 50 K/s was carried out to improve 
chemical homogeneity o f the alloys [8]. 
The coating was deposited on steel substrate by 
cathode-vacuum-arc method in a Bulat-6 setup [8] at a 
substrate bias Us = 100 V and the current arc did not 
exceed 85 A. The substrate was heated to 400°C before 
deposition. The deposition rate was set at 1.5 nm/sec. 
The elemental composition of the (Ti-Hf-Zr-V-Nb)N 
coatings and surface morphology were determined us-
ing a scanning electron microscope with EDS-analysis 
JEOL – 7000F (Japan) and JSM-6010LA 
InTouchScope. To perform the elemental analysis in 
the depth of the coating, we employed the Rutherford 
backscattering (RBS) method with He+ ions of 1.7 MeV 
at normal incidence (the scattering angle was θ=170°). 
The energy resolution of ion detector was 17 keV. The 
dose of helium ions was 5 µCi. The standard SIMNRA 
software [9] was used for processing RBS spectra and 
obtains profiles of elements distribution in depth of the 
coating.  
One of the effective methods of investigation of 
depth profile ion sputtering techniques: secondary ion 
mass spectrometry (SIMS) and glow discharge mass 
spectrometry (GDMS) [10-14]. For GDMS analysis we 
used DC 1.8 kV cathode voltage and 0.2 Torr Ar pres-
sure. GDMS analyser SMWJ-01 [15] is equipped with 
SRS-300 quadrupole mass analyser with 6 mm diame-
ter rods. For SIMS depth profile analysis we used Ar+, 
3 keV, 1.5 µA ion beam. SIMS analyser SAJW-05 [16] is 
equipped with Physical Electronics 06-350E ion gun 
and QMA-410 Balzers quadrupole mass analyser with 
16 mm diameter rods. 
 
3. RESULTS AND DISCUSSION  
 
Fig. 1 shows the result of studies of the surface, 
which were obtained using SEM. As we can see from 
Fig. 1 the droplet fraction with a size of 10-15 µm have 
been formed on the surface of nitride coatings during 
the deposition process. The reflections with the strong-
est intensity were (111) and (220) XRD lines (see e.g, 
samples 512, 514, 523). Earlier the works [26-28] have 
shown that the competition between surface and strain 
energy determines in general preferred orientation of 
nitride coatings (OEM model). 
 A.A. BAGDASARYAN, M.O. BILOKUR PROC. NAP 3, 01NTF19 (2014) 
 
 
01NTF19-2 
Table 1 – Deposition conditions for multicomponent coatings (Ti-Hf-Zr-V-Nb)N 
 
№ Us, В P, Pa 
Concentration, % 
N Ti V Zr Nb Hf 
509 100 3 10-2 44.70 25.31 4.57 7.60 7.99 9.83 
515 200 3 10-2 36.05 20.13 2.28 17.12 17.50 6.93 
510 50 2 10-1 49.11 19.67 5.65 7.68 8.24 9.64 
506 100 2 10-1 49.05 22.92 5.04 6.84 7.47 8.68 
514 200 2 10-1 47.69 16.41 1.93 13.34 13.90 6.72 
507 50 5 10-1 51.13 25.31 4.72 5.70 6.31 6.84 
505 110 5 10-1 49.15 16.63 5.91 8.17 8.88 11.26 
 
According to this model, the competing planes in the 
film with NaCl-type structure are the (200) plane with 
the lowest surface energy, the (111) plane with the low-
est strain energy and the (220) plane with the lowest 
stopping energy. However, much of studies have showed 
that there is no universal relation between orientation 
and intrinsic stress, and the change in the stress state 
with the increasing coating thickness 21-24]. 
According to recent works [21, 23-25] the kinetic 
constraints are assumed to affect the preferential ori-
entation (anisotropy in surface diffusivities, adatom 
mobilities and collisional cascade effects). On the one 
hand, the (111) plane is more close-packed of NaCl  
 
 
 
Fig. 1 – The results of XRD diffraction analysis for 
samples (according to the Table 1) 
 
structure, while the [220] plane is the most open chan-
neling direction. Consequently, the (220) plane have a  
higher probability of survival than the (111) planes 
(anisotropy of collision effect). On the other hand, the 
diffusion of metal adatoms on the (111) surface is less 
than on the (200) surface, that’s why adatoms on (200) 
planes can be incorporated into the (111) plane. There-
fore, the (111) preferred orientation appears. As a re-
sult, the preferred orientation of nitride coating devel-
ops through a complex interplay between “kinetic” ef-
fects, which associated with the growth process itself. 
In the current system, the nitrides of constituting 
elements (TiN, VN, ZrN, HfN and NbN) represent cubic 
phase structure NaCl (see table. 2). On this basis, we 
can make an assumption about the formation of coat-
ings obtained in the single-phase solid solution with an 
fcc lattice with randomly distributed atoms of the con-
stituent elements. In confirmation of this hypothesis it 
would be useful to compare values of the diffraction 
angle responsible for the reflection from the (111) plane 
and the lattice parameters for binary nitrides and ni-
tride coatings by MHEAN type. As can be seen in Fig. 1 
reflex position corresponding to reflection from the 
(111) plane corresponds to the 35,8°angle, which is ap-
proximately equal to the average angle which corre-
sponds to (111) reflex for binary nitrides constituents 
(see Table. 2). The lattice parameter measured for ni-
tride coating (0.4376 nm) is also slightly different from 
the lattice parameter of binary nitrides. Thus, the ar-
guments indicate formation of a single phase solid solu-
tion with a simple crystal lattice of a nitride-based sys-
tem Ti-Hf-Zr-V-Nb alloy. 
In the same time ion sputtering techniques is mainly 
used for depth profile analysis [18-20]. In our work we 
used secondary ion mass spectrometry (SIMS) and glow 
discharge mass spectrometry (GDMS) for investigation 
depth profile. Both methods use argon sputtering, how-
ever the ionization mechanisms of the sputtered mate-
rial are different. In SIMS, the ionization occurs at the 
bombardment surface, and neighboring atoms influence 
strongly the ionization process due to the so-called ma-
trix effect, the process. In GDMS, ionization occurs 
mainly above bombardment surface in glow discharge 
and the matrix effects are negligible. It should be noted 
that these methods are destructive. Fig. 2 shows the 
sample after SIMS and GDMS analyses.  
Mass spectra registered with GDMS and SIMS are 
shown in Fig. 3 and raw data of depth profile analysis 
are shown in Fig. 4. 
Sputtering conditions in the two methods differed 
very much. Sputtering rate in GDMS analysis was 
5.7 nm/s, while in SIMS sputtering rate was 0.046 nm/s 
i.e. 2.8 nm/min. As we can see from Fig. 5 the surface of 
 
 ANALYSIS OF MORPHOLOGY AND ELEMENTAL COMPOSITION… PROC. NAP 3, 01NTF19 (2014) 
 
 
01NTF19-3 
Table 2 – The crystal structure of the constituent elements of the binary nitride (Ti-Hf-Zr-V-Nb) N coatings and the value of the 
diffraction angle responsible for the reflection from the (111) plane 
 
Crystal structure 
TiN VN ZrN HfN NbN 
(Ti-Hf-Zr-V-
Nb)N 
FCC FCC FCC FCC FCC FCC 
2θ (angle) 35.30 35.5 33.89 33.6 36 35.8 
Lattice parameter, nm 0.424 0.4132 0.458 0.452 0.442 0.4376 
 
 
 
Fig. 2 – The sample surface after SIMS and GDMS analyses 
 
nitride coating is covered with a thin oxide film, as de-
tected species are ZrO, NbO, HfO and ZrO2 ions and 
also contains the high concentration of titanium and 
vanadium. The presence of uncontrolled impurities (H, 
C and O) is obviously connected with the residual gases 
in the working chamber. 
Ions currents are shown versus sputtering time in 
seconds. Raw data of GDMS show strong signal of mass 
14 (N+). This signal remains strong after sputtering the 
interface between nitride and the substrate. So it 
means that this signal is background affected. Namely 
in GDMS we detect strong so called plasma noise of 
mass 14. Also as we can see from Fig. 4 in SIMS tech-
nique the ion current decreases with sputtering time, 
obvious due to the sputtering of surface layer, which 
include the oxygen. In the other had, we can see the 
initial rise of ion current in GDMS technique due to the 
development of direct current glow discharge condition 
Basing on the concentration data obtained by EDX 
technique (N – 44.7%, Ti – 25.31%, V – 4.57%, Zr – 
7.60%, Nb – 7.99%, Hf – 9.83%) we perform normaliza-
tion of the registered ions currents following formula: 
Ix/∑ Ix, where Ix is the normalized ion current of a giv-
en component X and ∑ Ix is the sum of the normalized 
ion currents of all registered components. It should be 
noted that the sensitivity factors used in SIMS differ 
up to two orders of magnitude and the ratio Ix/∑ Ix rep-
resent the relative concentration of elements if we as-
sume equal matrix effect for all elements. In the other 
hand, the sensitivity of GDMS are close to 1 and the 
current ratio Ix/∑ Ix also indicate the relative concen-
tration of analyzed elements since no matrix effect are 
present in this method [6].  
Ions currents are shown versus sputtering time in 
seconds. Raw data of GDMS show strong signal of mass 
14 (N+).  
 
0 20 40 60 80 100 120 140 160 180 200
1E-17
1E-16
1E-15
1E-14
1E-13
1E-12 (Ti, V, Hf, Nb, Zr)N/steel
Ti
+
 
 
io
n
 c
u
rr
e
n
t 
[A
]
m/z [a.m.u.]
N509 GDMS mass spectrum 
V
+
Hf
+
Ta
+
Zr
+
Nb
+
Ar
2
+
 
Fig. 3 – SIMS and GDMS mass spectra for the sample registered in range up to 200 a.m.u. 
 
 
 
 
 
 A.A. BAGDASARYAN, M.O. BILOKUR PROC. NAP 3, 01NTF19 (2014) 
 
 
01NTF19-4 
0 400 800
1E-16
1E-15
1E-14
1E-13
1E-12
0 400 800 1200 0 400 800
 
 
io
n
 c
u
rr
e
n
t 
[A
]
N509 GDMS raw data
 
 
time [s]
 N
 Ti
 V
 Zr
 Nb
 Hf
 Fe
 
 
0 10 20
0.1
1
10
100
1000
10000
s
e
c
o
n
d
a
ry
 i
o
n
 c
u
rr
e
n
t 
[c
.p
.s
.]
time [h]
 N
 O
 Ti
 V
 Zr
 Nb
 Hf
 Fe
N509 SIMS raw data
 
Fig. 4 – Depth profile analysis. Raw data of GDMS (three analysed spots) and SIMS (one crater) 
 
This signal remains strong after sputtering the in-
terface between nitride and the substrate. So it means 
that this signal is background affected. Namely in 
GDMS we detect strong so called plasma noise of mass 
14. Also as we can see from Fig. 4 in SIMS technique 
the ion current decreases with sputtering time, obvious 
due to the sputtering of surface layer, which include 
the oxygen. In the other had, we can see the initial rise 
of ion current in GDMS technique due to the develop-
ment of direct current glow discharge condition. 
Basing on the concentration data obtained by EDX 
technique (N – 44.7%, Ti – 25.31%, V – 4.57%, Zr – 
7.60%, Nb – 7.99%, Hf – 9.83%) we perform normaliza-
tion of the registered ions currents following formula: 
Ix/∑ Ix, where Ix is the normalized ion current of a giv-
en component X and ∑ Ix is the sum of the normalized 
ion currents of all registered components. It should be 
noted that the sensitivity factors used in SIMS differ 
up to two orders of magnitude and the ratio Ix/∑ Ix rep-
resent the relative concentration of elements if we as-
sume equal matrix effect for all elements. In the other 
hand, the sensitivity of GDMS are close to 1 and the 
current ratio Ix/∑ Ix also indicate the relative concen-
tration of analyzed elements since no matrix effect are 
present in this method [6]. 
0 400 800
0.1
1
10
100
0 400 800
0.1
1
10
100
 
 
I x
/
I x
 [
%
]
time [s]
 N
 Ti
 V
 Zr
 Nb
 Hf
 Fe
 
 
time [s]
N509 GDMS depth profile
0 5 10 15 20 25 30
0.1
1
10
100
 
 
I x
/
I x
 [
%
]
time [h]
 N
 Ti
 V
 Zr
 Nb
 Hf
 Fe
N509 SIMS depth profile
 
Fig. 5 – Depth profile analysis of the sample (including nitrogen) – left GDMS and right SIMS 
 
 
 
 ANALYSIS OF MORPHOLOGY AND ELEMENTAL COMPOSITION… PROC. NAP 3, 01NTF19 (2014) 
 
 
01NTF19-5 
Both methods show element profiles, as we can see 
the result show the same compositional changes in the 
analyzed sample. The Hf, Zr, Nb and V profiles are 
similar in SIMS and GDMS methods, while the titani-
um profiles are different in two methods. Both tech-
niques show that distribution of metal components 
across the layer is stable, however titanium concentra-
tion slightly increases towards the interface, while the 
concentrations of Nb, Hf, Zr slightly decrease. 
 
 
 
 
4. CONCLUSIONS 
 
New nitride coating based on the TiHfVNbZr high-
entropy alloy has been fabricated. The coating exhibits a 
single cubic (NA-Cl) nitride phase. By combining the 
results of the RBS and the results obtained with ion 
sputtering technique (SIMS and GDMS) methods we 
received a more realistic picture of the distribution of 
constituent elements over the depth of the layer. Both 
analytical methods, SIMS and GDMS give same results. 
However, the slight deviation in case of nitrogen direc-
tion connected with the strong influence of plasma noise.  
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Analysis of Morphology and Elemental Composition of  (Ti-Zr-Hf-V-Nb)N High-entropy Alloys

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Analysis of Morphology and Elemental Composition of (Ti-Zr-Hf-V-Nb)N High-entropy Alloys

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