Ion-induced formation of micropolycrystalline Nb1-xCx (0 ≤ x < 0.3) thick coatings with quasi-ternary phase structure
Structure and superconductivity of thick polycrystalline niobium-carbon coatings (Nb1-xCx, 0 ≤ x < 0.3) deposited from low-energy self-ion-atomic Nb- and C- fluxes onto substrates with the temperature range 500…650 K were studied by X-ray diffraction (XRD) analysis, transmission electron microsco...
Gespeichert in:
| Datum: | 2001 |
|---|---|
| Hauptverfasser: | , |
| Format: | Artikel |
| Sprache: | English |
| Veröffentlicht: |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
|
| Schriftenreihe: | Вопросы атомной науки и техники |
| Schlagworte: | |
| Online Zugang: | http://dspace.nbuv.gov.ua/handle/123456789/78272 |
| Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Zitieren: | Ion-induced formation of micropolycrystalline Nb1-xCx (0 ≤ x < 0.3) thick coatings with quasi-ternary phase structure / S.N. Sleptsov, A.N. Sleptsov // Вопросы атомной науки и техники. — 2001. — № 4. — С. 39-45. — Бібліогр.: 52 назв. — англ. |
Institution
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
irk-123456789-78272 |
|---|---|
| record_format |
dspace |
| spelling |
irk-123456789-782722015-03-14T03:02:21Z Ion-induced formation of micropolycrystalline Nb1-xCx (0 ≤ x < 0.3) thick coatings with quasi-ternary phase structure Sleptsov, S.N. Sleptsov, A.N. Физика радиационных повреждений и явлений в твердых телах Structure and superconductivity of thick polycrystalline niobium-carbon coatings (Nb1-xCx, 0 ≤ x < 0.3) deposited from low-energy self-ion-atomic Nb- and C- fluxes onto substrates with the temperature range 500…650 K were studied by X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), electron diffraction, TEM of oxidic replicas and resistivity measurement method at low temperature. It is founded, that Nb1-xCx coatings with carbon concentration range 9…15 at.% have an unusual high superconducting transition temperature Tc ≈ 12 K. Dependency of critical current density of these coatings on temperature is not monotonous and have a sharp bend near TC ≈ 9.5 K Structural analysis of these coatings has revealed they have a quasi-ternary phase composition consisting of Nb(b.c.c.), subcarbide Nb₂C(c.p.h.) and metastable carbide 'NbCx' with f.c.c. structure. The results obtained are discussed from a point of view of 'NbCx' phase forming at Nb and Nb₂C phases interface. It is also shown, that Nb1-xCx coatings with carbon concentration less than 5 at.% revealed supersaturated solid solution and have TC ≈ 9.5 K. Kinetics of diffusive decomposition of niobium-carbon coatings during isothermal annealing was also investigated. Структура та надпровідність товстих полікрісталічних ніобій-вуглецевих покриттів (Nb1-xCx, 0 ≤ x < 0,3), осаджених із низькоенергетичних самоіонних-атомних Nb- и C- потоків на підкладки у температурному інтервалі 500...650 К були вивчені за допомогою рентгеноструктурного аналізу, просвічуючи електронної мікроскопії окісних реплік та методом вимірювання питомого опору при низький температурі. Було встановлено, що Nb1-xCx покриття з концентрацією вуглецю в інтервалі 9...15 ат.% мають надзвичайно високу температуру надпровідного переходу Тс ≈ 12 К. Залежність критичної щільності цих покриттів від температури не є монотонною і виявляє крутий ізгіб величин біля Тс ≈ 9,5. Структурний аналіз цих покриттів показав, що вони мають квазіпотрійний фазовий склад, що складається із Nb(ОЦК), субкарбіда Nb₂C (ГПУ) та метастабільного карбіду NbCx з ГЦК-структурою. Отриманы результати обговорюються з точки зору NbCx -фази, яка утворюється на поверхні розподілу Nb та Nb₂C-фаз. Показано також, що Nb1-xCx -покриття з концентрацією вуглецю нижче 5 ат.% виявляють пересичений твердий розчин і мають Тс ≈ 9,5 К. Була також досліджена кінетика фаз дифузного розкладу ніобій-вуглецевих покриттів у процесі ізотермічного відпалу. Структура и сверхпроводимость толстых поликристаллических ниобий-углеродных покрытий (Nb1-xCx, 0≤ x <0,3), осажденных из низкоэнергетических самоионных-атомных Nb- и C- потоков на подложки в температурном интервале 500…650 К, были изучены рентгеноструктурным анализом (ХRD), просвечивающей электронной микроскопией (TEM), дифракцией электронов, просвечивающей микроскопией окисных реплик и методом измерений идеального сопротивления при низкой температуре. Было установлено, что Nb1-xCx покрытия c концентрацией углерода в интервале 9…15 ат.% обладают необычно высокой температурой сверхпроводящего перехода Тс∼12 К. Зависимость критической плотности этих покрытий от температуры не является монотонной и обнаруживает крутой изгиб около Тс≈9,5 К. Структурный анализ этих покрытий показал, что они имеют квазитройной фазовый состав, состоящий из Nb (ОЦК), субкарбида Nb₂C (ГПУ) и метастабильного карбида NbCx c ГЦК-структурой. Полученные результаты обсуждаются с точки зрения NbCx -фазы, формирующейся на поверхности раздела Nb- и Nb₂C- фаз. Показано также, что Nb1-xCx- покрытия с концентрацией углерода ниже 5 ат.% обнаруживают перенасыщенный твердый раствор и имеют Тс ≈ 9,5 К. Была также исследована кинетика диффузного разложения ниобий-углеродных покрытий в процессе изотермического отжига. 2001 Article Ion-induced formation of micropolycrystalline Nb1-xCx (0 ≤ x < 0.3) thick coatings with quasi-ternary phase structure / S.N. Sleptsov, A.N. Sleptsov // Вопросы атомной науки и техники. — 2001. — № 4. — С. 39-45. — Бібліогр.: 52 назв. — англ. 1562-6016 http://dspace.nbuv.gov.ua/handle/123456789/78272 669-405:539.16.04 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| topic |
Физика радиационных повреждений и явлений в твердых телах Физика радиационных повреждений и явлений в твердых телах |
| spellingShingle |
Физика радиационных повреждений и явлений в твердых телах Физика радиационных повреждений и явлений в твердых телах Sleptsov, S.N. Sleptsov, A.N. Ion-induced formation of micropolycrystalline Nb1-xCx (0 ≤ x < 0.3) thick coatings with quasi-ternary phase structure Вопросы атомной науки и техники |
| description |
Structure and superconductivity of thick polycrystalline niobium-carbon coatings (Nb1-xCx, 0 ≤ x < 0.3) deposited from low-energy self-ion-atomic Nb- and C- fluxes onto substrates with the temperature range 500…650 K were studied by X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), electron diffraction, TEM of oxidic replicas and resistivity measurement method at low temperature. It is founded, that Nb1-xCx coatings with carbon concentration range 9…15 at.% have an unusual high superconducting transition temperature Tc ≈ 12 K. Dependency of critical current density of these coatings on temperature is not monotonous and have a sharp bend near TC ≈ 9.5 K Structural analysis of these coatings has revealed they have a quasi-ternary phase composition consisting of Nb(b.c.c.), subcarbide Nb₂C(c.p.h.) and metastable carbide 'NbCx' with f.c.c. structure. The results obtained are discussed from a point of view of 'NbCx' phase forming at Nb and Nb₂C phases interface. It is also shown, that Nb1-xCx coatings with carbon concentration less than 5 at.% revealed supersaturated solid solution and have TC ≈ 9.5 K. Kinetics of diffusive decomposition of niobium-carbon coatings during isothermal annealing was also investigated. |
| format |
Article |
| author |
Sleptsov, S.N. Sleptsov, A.N. |
| author_facet |
Sleptsov, S.N. Sleptsov, A.N. |
| author_sort |
Sleptsov, S.N. |
| title |
Ion-induced formation of micropolycrystalline Nb1-xCx (0 ≤ x < 0.3) thick coatings with quasi-ternary phase structure |
| title_short |
Ion-induced formation of micropolycrystalline Nb1-xCx (0 ≤ x < 0.3) thick coatings with quasi-ternary phase structure |
| title_full |
Ion-induced formation of micropolycrystalline Nb1-xCx (0 ≤ x < 0.3) thick coatings with quasi-ternary phase structure |
| title_fullStr |
Ion-induced formation of micropolycrystalline Nb1-xCx (0 ≤ x < 0.3) thick coatings with quasi-ternary phase structure |
| title_full_unstemmed |
Ion-induced formation of micropolycrystalline Nb1-xCx (0 ≤ x < 0.3) thick coatings with quasi-ternary phase structure |
| title_sort |
ion-induced formation of micropolycrystalline nb1-xcx (0 ≤ x < 0.3) thick coatings with quasi-ternary phase structure |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2001 |
| topic_facet |
Физика радиационных повреждений и явлений в твердых телах |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/78272 |
| citation_txt |
Ion-induced formation of micropolycrystalline Nb1-xCx (0 ≤ x < 0.3) thick coatings with quasi-ternary phase structure / S.N. Sleptsov, A.N. Sleptsov // Вопросы атомной науки и техники. — 2001. — № 4. — С. 39-45. — Бібліогр.: 52 назв. — англ. |
| series |
Вопросы атомной науки и техники |
| work_keys_str_mv |
AT sleptsovsn ioninducedformationofmicropolycrystallinenb1xcx0x03thickcoatingswithquasiternaryphasestructure AT sleptsovan ioninducedformationofmicropolycrystallinenb1xcx0x03thickcoatingswithquasiternaryphasestructure |
| first_indexed |
2025-07-06T02:25:51Z |
| last_indexed |
2025-07-06T02:25:51Z |
| _version_ |
1836862670657028096 |
| fulltext |
УДК 669-405:539.16.04
ION-INDUCED FORMATION OF MICROPOLYCRYSTALLINE
Nb1-xCx (0 ≤ x < 0.3) THICK COATINGS WITH QUASI-TERNARY
PHASE STRUCTURE
S. N. Sleptsov and A. N. Sleptsov
National Scientific Center «Kharkov Institute of Physics and Technology»,
1 Akademicheskaya St., Kharkov 61108, Ukraine
E-mail: glss@kipt.kharkov.ua
Структура и сверхпроводимость толстых поликристаллических ниобий-углеродных покрытий (Nb1-xCx, 0≤ x <0,3),
осажденных из низкоэнергетических самоионных-атомных Nb- и C- потоков на подложки в температурном интервале
500…650 К, были изучены рентгеноструктурным анализом (ХRD), просвечивающей электронной микроскопией (TEM),
дифракцией электронов, просвечивающей микроскопией окисных реплик и методом измерений идеального сопротивле-
ния при низкой температуре. Было установлено, что Nb1-xCx покрытия c концентрацией углерода в интервале 9…15 ат.%
обладают необычно высокой температурой сверхпроводящего перехода Тс∼12 К. Зависимость критической плотности
этих покрытий от температуры не является монотонной и обнаруживает крутой изгиб около Тс≈9,5 К. Структурный ана-
лиз этих покрытий показал, что они имеют квазитройной фазовый состав, состоящий из Nb (ОЦК), субкарбида Nb2C
(ГПУ) и метастабильного карбида NbCx c ГЦК-структурой. Полученные результаты обсуждаются с точки зрения NbCx
-фазы, формирующейся на поверхности раздела Nb- и Nb2C- фаз. Показано также, что Nb1-xCx- покрытия с концентраци-
ей углерода ниже 5 ат.% обнаруживают перенасыщенный твердый раствор и имеют Тс ≈ 9,5 К. Была также исследована
кинетика диффузного разложения ниобий-углеродных покрытий в процессе изотермического отжига.
Структура та надпровідність товстих полікрісталічних ніобій-вуглецевих покриттів (Nb1-xCx, 0 ≤ x < 0,3), осадже-
них із низькоенергетичних самоіонних-атомних Nb- и C- потоків на підкладки у температурному інтервалі 500...650 К
були вивчені за допомогою рентгеноструктурного аналізу, просвічуючи електронної мікроскопії окісних реплік та
методом вимірювання питомого опору при низький температурі. Було встановлено, що Nb1-xCx покриття з концентрацією
вуглецю в інтервалі 9...15 ат.% мають надзвичайно високу температуру надпровідного переходу Тс ≈ 12 К. Залежність
критичної щільності цих покриттів від температури не є монотонною і виявляє крутий ізгіб величин біля Тс ≈ 9,5.
Структурний аналіз цих покриттів показав, що вони мають квазіпотрійний фазовий склад, що складається із Nb(ОЦК),
субкарбіда Nb2C (ГПУ) та метастабільного карбіду NbCx з ГЦК-структурою. Отриманы результати обговорюються з точ-
ки зору NbCx -фази, яка утворюється на поверхні розподілу Nb та Nb2C-фаз. Показано також, що Nb1-xCx -покриття з
концентрацією вуглецю нижче 5 ат.% виявляють пересичений твердий розчин і мають Тс ≈ 9,5 К. Була також досліджена
кінетика фаз дифузного розкладу ніобій-вуглецевих покриттів у процесі ізотермічного відпалу.
Structure and superconductivity of thick polycrystalline niobium-carbon coatings (Nb1-xCx, 0≤x<0.3) deposited from low-en-
ergy self-ion-atomic Nb- and C- fluxes onto substrates with the temperature range 500…650 K were studied by X-ray diffraction
(XRD) analysis, transmission electron microscopy (TEM), electron diffraction, TEM of oxidic replicas and resistivity measure-
ment method at low temperature. It is founded, that Nb1-xCx coatings with carbon concentration range 9…15 at.% have an unusu-
al high superconducting transition temperature TC ~12 K. Dependency of critical current density of these coatings on temperature
is not monotonous and have a sharp bend near TC ≈ 9.5 K Structural analysis of these coatings has revealed they have a quasi-
ternary phase composition consisting of Nb(b.c.c.), subcarbide Nb2C(c.p.h.) and metastable carbide 'NbCx' with f.c.c. structure.
The results obtained are discussed from a point of view of 'NbCx' phase forming at Nb and Nb2C phases interface. It is also
shown, that Nb1-xCx coatings with carbon concentration less than 5 at.% revealed supersaturated solid solution and have TC ≈ 9.5
K. Kinetics of diffusive decomposition of niobium-carbon coatings during isothermal annealing was also investigated.
1. INTRODUCTION
Thick coatings and thin films of carbides and ni-
trides of transitional refractory metals have found wide
applications in different industrial branches, since they
possess both high protective properties and unique elec-
trophysical characteristics which are stable in wide tem-
perature region [1-5]. These coatings, as a rule, are syn-
thesized in vacuum by simultaneous deposition of ion
and atomic fluxes of metal and metalloid (carbon and/or
nitrogen) onto substrates with temperature TS< 0.3Tm,
where Tm is the melting temperature of condensable
material [6-12].
At present a great amount of investigations of the
influence of ion irradiation on the kinetics of coatings
formation have been carried out with the purpose of op-
timization of operational characteristics of metal-metal-
loid coatings. It was established, that ion irradiation in-
duces formation of polycrystalline coatings with
nonequilibrium metastable structures (supersaturating
solid solutions [13-16], new phases [17-21], polymor-
phous modifications [22-27] etc.), which are absent on
equilibrium state diagrams.
Supersaturating solid solutions of metalloid atoms in
metal matrix are the object of increased interest of
many researchers. It was found, that these solid
solutions can decay with the formation of precipitates
of dispersion carbides (or nitrides) depending on
__________________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №4.
Серия: Физика радиационных повреждений и радиационное материаловедение (80), с.39-45.
39
conditions of coatings syntheses. In turn, these precipi-
tates can induce either polymorphous transformation of
metal matrix [22,23,24] or formation of a new
metastable metal-metalloid phases [10,16,19,26,28]. As
a result of such structural transformations,
micropolycrystalline heterophase coatings are formed.
These coatings, as a rule, have anomalously high
mechanical properties as well as electrophysical ones.
High values of superconducting transition tempera-
ture TC = 11.5…12.5 K were discovered during investi-
gation of superconductivity parameters of niobium-car-
bon coatings in carbon concentration range 6…20 at.%
which were prepared by ion-atomic sputtering method [
26,29]. Authors [29] suppose, that high TC values can be
connected with a high-stoichiometric phase of niobium
carbide which forms in these coatings.
In the present work, we report a study carried out on
microstructure, composition and superconductivity pa-
rameters of niobium-carbon (Nb1-xCx, 0 ≤ x < 0.3) coat-
ings prepared by simultaneous deposition of self-ion-
atomic Nb and C fluxes. X-ray diffraction (XRD) anal-
ysis, transmission electron microscopy (TEM), electron
diffraction, electron microscopy of oxidic replicas and
resistivity measurement method at low temperature
were used in these investigations. The results thus
obtained are discussed.
2. EXPERIMENTAL DETAILS
Niobium-carbon coatings (100…110 µm) were pre-
pared onto copper substrates (30 mm × 30 mm × 2 mm)
by condensation of self-ion-atomic fluxes of metal and
carbon using an atom-ionic sputtering method [30,31].
A purity of used materials was better than 99.91 at.%.
The substrates were polished mechanically to give a
final mirror-like surface using 1 µm particle size
alumina powder. Cleaning of substrates has been
carried out by following a well-known procedure with a
final rinse in alcohol. The substrates were located in
multi-position heating holder, which allows to support
and measure the substrates temperature during coatings
deposition in the region from 500 to 650 K. The
vacuum system was pumped down to 1.3×10−4 Pa. Ion
energy of both metal and carbon was 250 eV and a ratio
of ion-to-vapor fluxes was equal to 0.1±0.01. The
deposition rate was (5.5±0.3) nm/sec. The detailed de-
scription of coatings deposition can be found in [31,32].
Composition of deposited coatings was determined
by means of nuclear reactions using electrostatic proton
accelerator with energy beam 4.5 MeV [33]. Nuclear re-
actions 13C(p,γ)14N, 12C(p,γ)13N and 13C(α,n)16O were
used for determination of carbon concentration. Nitro-
gen, oxygen and hydrogen concentrations were ob-
tained with using nuclear reactions 15N(p,α,γ)12C, 18O(α
,p,γ)21Ne and 1H(α,γ)12C respectively [34]. The mea-
surement accuracy of concentrations of carbon, nitro-
gen, oxygen and hydrogen was better 1×10−2 at. %.
Investigations of crystal structure and phase compo-
sition of niobium-carbon coatings in initial state and af-
ter thermal annealing (T = 1000 K for t = 0.3, 0.5 and 1
−5 hours) were carried out using DRON-3M X-ray
diffractometer (Cu K∝- radiation) and electron micro-
scopes EVM-100L and JEM-100CX both operated at
100 kV. Lattice constants of both niobium and carbides
phases of deposited Nb1-xCx coatings were evaluated
from the XRD patterns which have been obtained
during examination of coatings in a free state (Nb1-xCx
coatings, detached from a substrate). The intrinsic ori-
ented microstrains (ε) of niobium matrix in the direc-
tion parallel to the substrate surface were determined
for samples in free state by well-known sin2ψ method [
35, 36]. Mechanical and chemical polishes of the
coatings were performed to study of coatings structure
into the depth. TEM of oxidic replicas [37] was used to
determine size, morphology and volume fraction of car-
bide phase particles.
The superconductivity parameters measurements of
samples were conducted by standard four-probe DC
technique in a helium cryostat. Temperature dependen-
cies of resistivity of Nb1-xCx samples were obtained in
the interval 4.2…300 K. Measurement accuracy of su-
perconducting transition temperature TC was better than
0.01K. Critical current density (JC) was determined
from the volt-ampere dependence at fixed temperature
in the interval 7…15 K in zero magnetic field.
3. RESULTS AND DISCUSSION
Investigation results of superconducting transition
temperature of niobium-carbon coatings are shown in
Fig. 1. As may be seen in Figure 1 dependence of super-
conducting transition temperature has a nonmonotonous
behavior as the C/Nb composition ratio increases. In the
region 0 ≤ C/Nb ≤ 0.1 temperature TC depends weakly
on carbon concentration and equals to (9.35±0.15) K.
Transitional width ∆TC = (0.6±0.01) K in this
concentration interval. TC behavior has bell-shape with
a maximum TC = 12.01 K at C/Nb ≈ 0.14 in the region
0.1 < C/Nb <0.2. In this concentration interval transi-
tional width increases in 2 times and it is equal to (1.2±
0.11) K. When the composition ratio increases above
C/Nb > 0.16 the values of both TC and ∆TC fall drasti-
cally to ~9.5 K and ~0.5 K respectively. The values of
superconductivity parameters do not change in the re-
gion 0.2 ≤ C/Nb < 0.3. It may be noted that the results
obtained are very near to values published in works [26,
29].
It is known that electrophysical properties of super-
conducting films unambiguously are determined by
their structure [38-45]. Therefore, detail investigations
of Nb1-xCx coatings structure have been carried out for
the interpretation of their superconducting parameters.
The results of these investigations have discovered un-
usual behavior of both phase state and microstructure of
the Nb1-xCx coatings on carbon content. These results
can be described as follows.Examinations of the niobi-
um-carbon coatings in the region 0≤ C/Nb< 0.05 (0≤ C
< 5 at.%) by TEM and XRD revealed a polycrystalline
single phase b.c.c. structure having (211) and (111) pre-
ferred orientations. Figure 2 depicts the electron micro-
graphs of Nb1-xCx coatings with various carbon concen-
tration. No extra reflections in electron diffraction pat-
__________________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №4.
Серия: Физика радиационных повреждений и радиационное материаловедение (80), с.39-45.
40
tern are observed, indicating that a carbide phase does
not form under these conditions. The structure with no
well-defined carbide precipitate often is named as 'mot-
tled' structure [28]. As the carbon concentration increas-
es the weight of crystallographic planes with preferred
(111) orientation rises, an average size of blocks (<D>)
of grains decreases from (61±3) nm to (42±5) nm, mi-
crodeformation value of crystal lattice grows from
0.025% to 0.042%, and the lattice constant of Nb-ma-
trix varies in the interval a = (0.33002±2 − 0.33005±3)
nm.
[C]/[Nb] , composition ratio
T
, K
C
0,00
13
12
11
10
9
8
0,05 0,10 0,15 0,20 0,25 0,30
Fig. 1. Dependence of a superconducting transition
temperature of niobium-carbon coatings prepared at TS
= (550±10) K vs. composition ratio C/Nb. Vertical bars
show a width of superconducting transition temperature
∆TC. (•) - initial state of Nb1-xCx coatings; (o) - state of
Nb1-xCx coatings after thermal annealing at T = 1000 K
for t = 2 h
Elemental analysis showed the concentration of
gases impurities are 0.1 at.% N, 0.08 at.% O and
0.51at.% H in all coatings. The dependence of lattice
constant on concentration of metalloid impurity (cX in
at.%) can be written as
a(nm) = 0.33000×(1 + kX×cX),
where kX is a constant for each impurity: kO= 0.0006±2,
kH=0.00015±2 [5,46], kN=0.0008±2 [5,46,47] and
kC=0.00044 [48] − 0.0012±2 [5,28,46,47].
Estimation of the lattice constant of Nb-matrix with
account of given relation and concentrations of metal-
loid impurities allows to conclude that gases atoms can
be partially in solid solution, and the highest possible
carbon content in solid solution can not exceed 0.2
at.%. The latter does not contradict the experimental
results of works [28,46,49]. Therefore, carbon excess
can form very fine (≤ 1 nm) carbide precipitates (not
detectable by TEM) in the host matrix as well as at the
boundaries of blocks (grains). The latter case really
takes place in coatings so far as the density of blocks
boundaries increases in ~2 times with carbon concentra-
tion growth.
XRD examinations of the carbon-doped niobium coat-
ings prepared in the composition ratio region 0.05≤
C/Nb<0.2 (5≤C<17at. %) showed a heterophase mi-
cropolycrystalline structure which consists of Nb-ma-
trix and Nb2C precipitates. Fig. 3 shows a typical θ-2θ
scan for a niobium-carbon coating obtained at substrate
temperature below 600 K. It is necessary to note, that a
noticeable broadening of diffraction peaks of both phas-
es as well as an increased background have been ob-
served for Nb1-xCx samples with carbon concentration
9…15 at.%.
a
b
Fig. 2. A bright-field electron micrograph and corre-
sponding electron diffraction pattern of Nb1-xCx coat-
ings deposited onto substrate with temperature (550±
10) K. a - 0.53 at.% C; b - 3.54 at.% C
The precipitates have a hexagonal W2C-type struc-
ture with the lattice constants a= 0.31262±4 nm and c=
0.4968±2 nm which are very near to published values
[1,2,49]. The lattice constant of Nb matrix does not
change in this concentration region and equals to a =
0.33005±4 nm. Crystallographic planes (110) and (111)
are preferred orientation planes for Nb2C and Nb phases
respectively. Microdeformation value of Nb-matrix ris-
es from 0.05% to 0.3% as the carbon concentration rises
up to ~12 at.%. Further increase of carbon concentra-
tion leads to decrease of ε-value down to ~0.06%. Aver-
age size of blocks of Nb grains is <D> = (40±5) nm and
depends weakly on carbon contents in coatings.
__________________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №4.
Серия: Физика радиационных повреждений и радиационное материаловедение (80), с.39-45.
41
However, <D> for the Nb2C precipitates depends on
carbon concentration as follows: (36±3), (17±3) and (32
±3) nm for ranges 5 ≤ C < 9 at. %, 9 ≤ C ≤ 15 at. % and
15 < C < 17 at. % consequently. Layerwise analysis of
structure of Nb1-xCx coatings using oxidic replicas
method and electron diffraction has allowed to detail
and supplement XRD analysis data. The results of these
investigations have confirmed the formation of two
polycrystalline Nb and Nb2C phases in the region 5≤C<
9 at.% (see Fig. 4).
Fig. 3. XRD pattern from a Nb1-xCx (7.5 at.% C) coating
deposited onto substrate with temperature (550±10) K.
The major X-ray diffraction peaks are indexed to the
Nb and Nb2C phases
Furthermore, it was established that for this concen-
tration region a volume fraction of Nb2C phase increas-
es from ∼0.18 up to 0.23 with rising of the carbon con-
centration. TEM of oxidic replicas of Nb1-xCx (9≤C≤15
at. %) coatings has revealed the extended areas of a new
phase around Nb2C precipitates in Nb-matrix such as
that depicted in Fig. 5. The micrograph shows that area
width of the new phase increases as the size of Nb2C
precipitates decreases. Electron diffraction examina-
tions of this phase showed f.c.c. NaCl-type structure
with the lattice constant 0.445 nm. Moreover, in this
concentration region great deviation (~40%) of volume
fraction of the Nb2C phase from an equilibrium value
was found. The similar deviations were also revealed in
[29]. It may be noted that the formation of such struc-
ture occurs in the region of an eutectic composition C =
(12±2) at.% [1,2,5,49].
The structure of Nb1-xCx (17≤C<23 at.%) coatings is
qualitatively similar to niobium-carbon coatings with
the concentration C= 5…9 at.%. Volume fraction of
Nb2C phase in these coatings is close to a
thermodynamic equilibrium value at carbon contents
more than 18 at.%.
Let's discuss obtained results. It is know, that super-
conducting transition temperature of Nb2C phase is ∼9.1
K [4,44,45], and TC of niobium changes from ~5 to ~9.7
K and depends on purity of niobium matrix [4,38-41].
As shown in [4,42,43], increasing of dispersity of niobi-
um matrix leads to increase TC on 0.3…0.5 K, and for-
mation of high-dispersion metal-metalloid precipitates
in Nb-matrix
induces the increasing of ∆TC and JC. Then, on the
basis of these data and obtained experimental results it
is possible to conclude that TC ~ 9.5 K for Nb1-xCx coat-
ings in concentration regions C/Nb<0.05 and C/Nb >
0.16 corresponds to the superconducting transition tem-
perature of niobium matrix. High value ∆TC ~ 0.5 K can
be stipulated by strain of a matrix lattice as a result of
nucleating of Nb2C phase for C/Nb< 0.05 region and as
a result of the increasing of volume fraction of the sub-
carbide precipitates for C/Nb > 0.16 region.
Fig. 4. A bright-field electron micrograph of oxidic
replica from a Nb1-xCx (7.2 at.% C) coating deposited
onto substrate with temperature (550±10) K. Bright
formations are attributed to Nb2C precipitates and gray
field is a niobium matrix
In the region 0.11≤C/Nb≤0.175 (9≤C≤15 at.%), as it
is shown above, considerable growth of TC and ∆TC val-
ues are observed. High-dispersion precipitates with
f.c.c. structure (a = 0.445 nm) were detected in the
same region. It is known [1,2,49], there is only carbide
NbCx (0.72≤ x ≤ 1) with f.c.c. structure in Nb-C system.
For this phase superconducting temperature and lattice
constant increases (TC = 0.32…14 K and a = (0.4430…
0.44707) nm) as carbon concentration grows from ~42
to 50 at.% [1-4,44, 45, 49,50]. Then, obtained experi-
mental results allow to conclude, that founded high-dis-
persion f.c.c. phase is a nonequilibrium ‘NbCx’ phase.
The formation of this phase can explain decreasing of
volume fraction of Nb2C precipitates, on the one hand,
and increasing of microdeformation of Nb-matrix, on
the other hand. It is necessary to note, the formation of
metastable ‘NbCx’ phase was founded by authors [51]
in ‘low-carbon’ alloy obtained by high-velocity quench-
ing and this phase was indexed as tetragonal distortion
of the cubic NbCx structure. Moreover, the formation of
nonequilibrium phase with f.c.c. structure at the inter-
face of Nb-matrix and Nb2C precipitates is like the
polymorphous transformation of host matrix Nb(b.c.c.)
→ Nb(f.c.c.) which can be induced by high-dispersion
__________________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №4.
Серия: Физика радиационных повреждений и радиационное материаловедение (80), с.39-45.
42
metal-metalloid precipitates [22,24].
However, this process takes place when metal-met-
alloid precipitates have a f.c.c. structure [22]. In our
case, the Nb2C precipitates, as shown above, have a
hexagonal structure. Moreover, as shown in [22], the
system consisting of three phases Nb(b.c.c.) +
Nb(f.c.c.) + Nb2C(c.p.h.) cannot be realized because its
free volume energy is higher than the energy of
Nb(f.c.c.) + NbC(f.c.c.) system.
a
b
Fig. 5 A bright-field electron micrograph of an oxidic
replica from a Nb1-xCx (11.2 at.% C) deposited onto sub-
strate with temperature (550±10) K. Bright formations
are attributed to precipitates of a Nb2C phase, gray
field is a Nb-matrix and dark fields around precipitates
correspond to a nonequilibrium phasе(a).
Electron diffraction pattern of a nonequilibrium phase
with the f.c.c. NaCl-type structure (b)
The measurements data of critical current density as
well as the investigations results of both microstructures
and superconducting temperature of Nb1-xCx samples af-
ter high-temperature annealing are additional arguments
confirming 'NbCx' phase presence in coatings with con-
centration (9…15) at.% C. Temperature dependencies
of critical current density of Nb1-xCx coatings are pre-
sented in Fig. 6. As may be seen in Fig. 6, for niobium-
carbon coating with 'NbCx' phase there is a 'stair' on
JC(T) dependence which is allocated near superconduct-
ing temperature of niobium matrix. Such effect takes
place in heterophase systems which have superconduct-
ing phases with different values TC and JC [3,4].
Isothermal annealing of Nb1-xCx coatings leads to
change of their structural state and superconducting pa-
rameters. For example, aging of coatings with 1…5
at.% C at T= 1000 K for t= 0.3 h induces the decay of
solid solution and the formation of very fine (~2 nm)
precipitates visible through structure factor contrast.
The precipitates grow up to ~4 and ~15 nm for the an-
nealing time 0.5 and 2 h respectively. At the same time
thermal annealing of samples with C = 9…15 at.%
causes dissolution of 'NbCx' phase, growth of Nb2C pre-
cipitates (<D> = 45 nm for t = 1 h, <D> = 63 nm for t =
5 h) and increasing of their volume fraction. 'NbCx'
phase is disappearing completely after annealing for t =
1 h (see Fig. 7).
8,0 8,5 9,0 9,5 10,0 10,5 11,0 11,5 12,0
100
101
102
103
104
105
T , K
J C
,
A
/ c
m
2
Fig. 6. Dependencies of a critical current density of the
Nb1-xCx coatings on temperature. () - Nb1-xCx coating
with 11.2 at.% C at the initial state; (∆) - Nb1-xCx coat-
ing with 11.2 at.% C after thermal annealing at T =
1000 K for t = 1 h and (o) - Nb coating with the residu-
al carbon content 0.2 at.%
Fig. 7. A bright-field electron micrograph of an oxidic
replica from a Nb1-xCx (11.2 at.% C) coating which has
been annealed at T =1000 K for t = 1 h. Bright forma-
tions are attributed to precipitates of a Nb2C phase and
gray field is a Nb-matrix
As a result the superconducting temperature of
coatings is falling down to ~9.5 K (see Fig. 1) and the
__________________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №4.
Серия: Физика радиационных повреждений и радиационное материаловедение (80), с.39-45.
43
'stair' on JC(T) dependence is disappearing (see Fig. 6).
The detailed description of kinetics of diffusive decom-
position of Nb1-xCx (9…15 at.% C) coatings will be pre-
sented in the next report.
4. CONCLUSION
Results of this investigation can be summarized as
follows:
1. High-rate condensation of self-ion-atomic fluxes
of niobium and carbon onto substrates with TS = (500…
650) K forms polycrystalline single phase coatings with
b.c.c. structure when carbon concentration does not ex-
ceed 5 at.%. Isothermal annealing of samples at T =
1000 K for t < 1 h does not lead to formation of a well-
defined carbide phase.
2. The heterophase polycrystalline structure consist-
ing of Nb (b.c.c.) matrix and Nb2C (c.p.h.) precipitates
is formed in the intervals 5…8 at.% C and 16…23 at.%
C. Volume fraction of Nb2C phase in these concentra-
tion regions is close to a thermodynamic equilibrium
value.
3. The structure of Nb1-xCx (9 ≤ C ≤ 15 at.%) coat-
ings represents a quasi-ternary micropolycrystalline
composition consisting of Nb(b.c.c.), Nb2C(c.p.h.) and
'NbCx'(f.c.c.) phases. Metastable 'NbCx' phase is formed
at Nb and Nb2C phases interface.
4. Formation of 'NbCx' phase leads to increasing of
superconducting transition temperature of niobium-car-
bon coatings up to ~12 K and explains considerable de-
creased (~40%) of Nb2C volume fraction in comparison
with a thermodynamic equilibrium value. Thermal
annealing of these coatings at T = 1250 K for t ≥ 1 h
causes dissolution of 'NbCx' phase and growth of both
the volume fraction and the precipitates size of Nb2C
phase.
Authors would like to express their gratitude to Pro-
fessor A. Bakai and Professor V. Finkel for helpful dis-
cussions. They are also indebted to Dr. V. Bryk, Dr. O.
Borodin and Dr. V. Shulaev and Dr. A. Sokol (Kharkov
Polytechnical University, Ukraine) for carrying out
TEM analysis and interpretation of some of electron
micrographs. Authors would like to thank Dr. V. Kras-
norutskiy (STC «Nuclear Fuel Cycle», Ukraine), Dr. J.
Cannon IV (Department of Energy, U.S.A.) and Dr. M.
Souknov (Kharkov University of Electronics, Ukraine)
for technical and financial supporting in preparation of
this manuscript.
REFERENCES
1.E.K.Storms. The refractory carbides. New York and
London: Academic Press, 1967, 304 p.
2.G.V.Samsonov (ed.). Carbides and alloys on their
base. Kiev: «Naukova Dumka», 1976, 267 p.
3.T.Lunhman and D.Dew-Hughes. Metallurgy of super-
conducting materials. New York and London:
Academic Press, 1979, 245 p.
4.E.M.Savitskiy Superconducting materials.
Moscow:”Metallurgy”, 1976, 295 p.
5.G.S.Burhanova and Yu.V.Yefimova (ed.). Refractory
metals and alloys. Moscow: “Metallurgy”, 1986, 352 p.
6.J.A.Thornton. High rate thick film growth //Ann. Rev.
Mater. Sci. 1977, v.7, p 239-260.
7.G.K.Wolf, M.Barth, W.Ensinger, and M.Hans. Ion-
beam-assisted deposition for low temperature formation
of coatings //Vacuum. 1990, v.41(4-6), p.1308-1309.
8. B.O.Johanson, U.Heimerson, M.K.Hibbs and J.-
E.Sundgren. Reactively magnetron sputtered Hf-N
films. I. Composition and structure//J. Appl. Phys.
1985, v.58(8), p.3104-3111.
9.O.Burat, D.Bouchier, V.Stambouli and G.Gautherin.
Characterization and growth mechanisms of boron ni-
tride films synthesized by ion-beam-assisted deposition
//J. Appl. Phys. 1990, v. 68(6), p.2780-2790.
10.A.S.Bakai, S.N.Sleptsov, L.V.Bulatova,
L.V.Polyakov , and A.N.Sleptsov . The structural-phase
state of thick Cr-C coatings deposited by reactive atom-
ion sputtering //Ukrainian Journal of Physics. 1995,
v.40(8), p.832-836 (in Russian).
11.O.Knotek, A.Barimani, B.Bosserhoff, and F.Loffler
Structure and properties of magnetron-sputtered Ti-V-N
coatings //Thin Solid Films. 1990, v.193/194, p.557-
564.
12.J.-E.Sundgren. Ion-assisted film growth: modifica-
tion of structure and chemistry //Vacuum. 1990, v.41(4-
6), p.1347-1349.
13.A.Aubert, J.Danroc, A.Gaucher and TJ.Perrat Hard
chrome and molybdenum coatings produced by physi-
cal vapor deposition //Thin Sold Films. 1985, v.126(1-
2)., p.61-67.
14.G.Cholvy, J.L.Derep and M.Gantois Characteriza-
tion and wear resistance of coatings in the Cr-C-N
ternary system deposited by physical vapor deposition
//Thin Sold Films. 1985, v.126(1-2), p.51-60.
15.S.K.Sharma . and J.P.Morlevat Structure of reactive-
ly sputtered chromium-carbon films //Thin Sold Films.
1988, v.156(2), p.307-314.
16. V.F.Rybalko, A.N.Morozov., I.S.Martynov and
S.A.Karpov. Effects of irradiation with inert and reac-
tive gas ions on the Fe and Cr film structure//Radiat.
Eff. and Defects in Solids. 1998, v.145, p.107-114.
17.M.Naka, S.Hanada and I.Okamoto Structure
chromium-carbon films formed by CVD method //Proc.
of the 5th Intern. Conf. on Rapidly Quenched Metals.
Wursburg. 3-7 September 1984. Elsevier Sci. Publ.,
1985, p.361-364.
18.S.N.Sleptsov, L.V.Bulatova, Yu.I.Polyakov and
A.N.Sleptsov Low-energy ion bombardment during
Cr:C films deposition from vapor phase: Effects on mi-
crostructure and phase state //Abstr. of the 8th Intern.
Meet. on Radiation Processing. (Sect. 7). Beijing. 13-18
September 1992. Edited by Wu Jilan. Press. IMR Cen-
ter, p.5.
19.V.Nolfi Frank Jr. (ed.). Phase transformation during
irradiation. London and New York: Applied Science
Publishers, 1983.
20.V.N.Bykov, V.A.Trojan, ZG.Gdorovtseva and
V.S.Khaimovich Phase transformation in thin solid
films by ion bombardment //Phys. Stat. Sol. (a). 1975,
v.32, p.53-57.
21. V.F.Rybalko, A.N.Morozov, I.S.Martynov and
S.A.Karpov Effects of irradiation with inert and reac-
__________________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №4.
Серия: Физика радиационных повреждений и радиационное материаловедение (80), с.39-45.
44
tive gas ions on the Fe and Cr film structure //Radiat.
Eff. and Defects in Solids. 1998, v.145, p.107-114.
22.K.L.Chopra., M.R.ndlett and R.H.Duff Face-cen-
tered cubic modification in sputtered films of tantalum,
molybdenum, tungsten, rhenium, hafnium and zirconi-
um //Phil. Mag. 1967, v.16(140), p.261-273.
23.P.V.Pavlov, D.I.Tetelbaum, A.V.Pavlov and
E.I..Zorin Structural transformation under bombard-
ment of iron, nickel, molybdenum by argon, nitrogen
and carbon ions //Doklady Akademii Nauk SSSR. 1974,
v.217, p.330-335 (in Russian)
24.A.S.Bakai, G.G.Kvachantiradze Induced polymor-
phous transformation in metals//Voprosy Atomnoy Nau-
ki i Tekhniki. Ser.: Radiation Damage Physics and
Radiation Technology. 1987, Issue 2(40), p.42-52 (in
Russian).
25.J.M.Belli, F.FKomarov and V.S.Tishkov Chemical
combination formation in transitional metals by ion
bombardment // Phys. Stat. Sol. (a). 1978, v.45, p.343-
349.
26.S.N.Sleptsov, A.S.Bakai, I.G.Marchenko,
Yu.I.Polyakov and .A.N.Sleptsov Induced polymor-
phous transitions by low-energy ion bombardment dur-
ing Nb:C films deposition // Abstr. of the 8th Intern.
Meet. on Radiation Processing. (Sect. 7). Beijing. 13-18
September 1992. Edited by Wu Jilan. Press. IMR Cen-
ter. P. 9.
27.V.F.Zelensky, I.M.Neklydov, I.S.Martynov., A.N.-
Morozov, S.V.Pistryak and V.F.Rybalko On the nature
of ion bombardment-indused phase transformations in
films of transition metals// Radiat. Eff. and Defects in
Solids. 1990, v.115, p.31-43.
28.R.K.Viswanadham and C.A.Wert. Electron micro-
scopic study of precipitation in the system niobium-car-
bon// J. of the Less-Common Metals. 1976, v.48, p.135-
150.
29.A.S.Bakai, S.N.Sleptsov, A.N.Sleptsov and
M.A.Tikhonovskiy The ion-induced structural-phase
state of niobium-carbon condensates deposited from
ion-plasma fluxes// Ukrainian Journal of Physics. 1995,
v.40(8), p.827-831 (in Russian).
30.V.A.Belous, G.N.Kartmazov, V.S.Pavlov, V.V.Sa-
fonov and P.A.Markov. Ion-plasma methods for coat-
ings deposition. Ion-atomic sputtering method: Preprint
KhFTI. N 88-31, Moscow: TcNIIAtominform, 1988 (in
Russian).
31..S.N.Sleptsov, L.V.Bulatova, I.G.Marchenko,
A.N.Sleptsov and Yu.I.Polyakov. Structural state of
thick niobium coatings deposited from self-ion-atomic
fluxes // Voprosy Atomnoy Nauki i Tekhniki. Ser.:
Radiation Damage Physics and Radiation Technology.
1993, v.1(60), p.62-69 (in Russian).
32.I.V.Aleksenko, L.V.Bulatova, N.P.Dikiy , S.V.Zarya,
G.N.Kartmazov, T.V.Kostritsa, Yu.V.Lukirskiy., N.P.-
Matyash, P.V.Platonov, Yu.I.Plyakov, S.N.Sleptsov and
T.P.Chernyayeva. Parameters investigation of both mi-
cro- and substructure of thick coatings deposited from
high-density atomic and ion-atomic fluxes in vacuum //
Voprosy Atomnoy Nauki i Tekhniki. Ser.: Radiation
Damage Physics and Radiation Technology. 1987, IS-
SUE 1(2), p.73-82 (in Russian).
33.Yu. P.Antuf’ev, N.P.Dikiy and V.D.Zabolotniy. Us-
ing of the nuclear reactions for study of the chemical
composition of a material // Voprosy Atomnoy Nauki i
Tekhniki. Ser.: General Nuclear Physics. 1987, v.1(37),
p.61-64 (in Russian).
34.Yu.P.Antuf’ev, N.P.Dikiy, V.D.Zabolotniy, A.S.Litvi-
nenko and P.P.Matyash. The determination of the ele-
mental composition of a material and depth distribution
of impurity atoms using the momentary radiation of nu-
clear reactions // Voprosy Atomnoy Nauki i Tekhniki.
Ser.: Radiation Damage Physics and Radiation
Technology. 1990, ISSUE 3(54), p.100-105 (in
Russian).
35.V.Valvoda and J.Musil. X-ray analysis of strain in ti-
tanium nitride layers // Thin Solid Films. 1987, v.149, p.
49-60.
36.M.Barral, J.L.Lebrun., J.M.Sprauel and G.Maeder
X-ray macrostress determination on textured material //
Metallurgical Transactions. 1987, v.18(A), p.1229-
1238.
37.G.Maeder X-Ray diffraction and stress measurement
// Chemica Scripta. 1986, v.26(A), p. 23-31.
38.A.A.Sokol, G.V.Izyumskaya, Yu.I.Polyakov,
S.N.Sleptsov and V.M.Shulaev Application of the oxi-
dic replicas for electron-microscopy investigation of the
dispersed-strengthened composition coatings on the
base of niobium // Zavodskaya Laboratoriya. 1990,
v.11, p.76-77 (in Russian).
39.G.Heim and E.Kay Ion implantation during film
growth and its effect on the superconducting properties
of niobium // J. Appl. Phys. 1975, v.46(9), p.4006-4011.
40.A.F.Mayadas, R.B.Laibowitz and J.J.Cuomo Electri-
cal characteristic of rf-sputtered single-crystal niobium
films //J.Appl. Phys. 1972, v.43(2), p.1287-1289.
41.V.P.Belevskiy and I.V.Gusev The influence of ion
bombardment during deposition on both the structure
and electrical properties of niobium films // Voprosy
Atomnoy Nauki i Tekhniki. Ser.: Radiation Damage
Physics and Radiation Technology. 1987, v.1(39),
p.101-108 (in Russian).
42.D.W.Face, S.T.Ruggiero and D.E.Prober. Ion-beam
deposition of Nb and Ta refractory superconducting
films // J. Vac. Sci. Technol. (A). 1985, v.1(2), p.326-
330.
43.A.P.Dem’yanchuk, E.V.Kovalenko and N.V.S-
tul’chikova. The influence of structure of niobium films
on superconductig properties under electrical current //
Fizika Tverdogo Tela. 1982, v.24(8), p.2403-2406 (in
Russian).
44.A.Ya.Vinnikov, O.V.Zharikov and Ch.V.Kopetskiy
Dependence of the critical current from the size grain in
the polycrystalline niobium // Pisma v ZhETF. 1974,
v.19(1), p.7-9 (in Russian).
45.A.L.Giorgi, E.G.Szklars and E.K.Storms. Effect of
composition on the superconducting transition tempera-
ture of tantalum carbide and niobium carbide // Phys.
Rev. 1962,v.125(3), p.837-838.
46.G.F.Hardy and J.K.Hulm. The superconductivity of
some metal compound // Phys. Rev. 1954 ,v.93(5),
p.1004-1016.
47.G.V.Zaharova, I.A.Popov, L.V.Zhorova and
__________________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №4.
Серия: Физика радиационных повреждений и радиационное материаловедение (80), с.39-45.
45
B.V.Fedin. Niobium and its alloys. Moscow: “Metallur-
gy”, 1961, 369 p. (in Russian).
48.F.T.Sisco and E.Epremian (ed.). Columbium and
Tantalum. New York and London: John Wiley, 1963.
49. H.W.Kihg Bull. Alloy Phase Diagrams. 1981, v. 2,
p.402.
50.J.F.Smith, O.N.Carlson and R.R.De Avillez. The nio-
bium-carbon system // Journal of Nuclear Materials.
1987,v. 148, p.1-16.
51.E.K.Storms and N.H.Krikorian The variation of lat-
tice parameter with carbon content of niobium carbide
// J. Phys. Chem. 1959, v. 63(10), p.1747-1749.
52.M.I.Pochon, C.R.McKimsey, R.A.Perkins and W.D.-
Forgeng // Reactive Metals. Vol. 2. Edited by Clough
W.R., New York, Interscience Publishers, 1959, p.327.
__________________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №4.
Серия: Физика радиационных повреждений и радиационное материаловедение (80), с.39-45.
46
ION-INDUCED FORMATION OF MICROPOLYCRYSTALLINE
Nb1-xCx (0 x 0.3) THICK COATINGS WITH QUASI-TERNARY
PHASE STRUCTURE
2. EXPERIMENTAL DETAILS
3. RESULTS AND DISCUSSION
4. CONCLUSION
References
|