The new measuring procedure of nanosized films mechanical characteristics is proposed. The method
provides laying of an explored material film on a surface of getter which containing gas. A film is locally
deformed to bubbles formation by gassing from getter. Mechanical properties of nanofilm are calculated by
measuring the sizes and the shape of the undamaged and destroyed bubbles. Mechanical properties of iron
nanofilm with thickness 30 nanometers were determined by the method.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3517

Filatov, A.V.

Pogorelov, A.E.

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 1 No 3, 03PCSI15 (2pp) (2012) 
 
 
2304-1862/2012/1(3)03PCSI15 (2) 03PCSI15 -1  2012 Sumy State University 
Method for Characterization of Nano-Films Mechanical Properties 
 
Aleksander V. Filatov, Alexander E. Pogorelov 
 
G.V. Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36, Vernadsky ave., 03142 Kiev, Ukraine 
 
(Received 23 June 2012; revised manuscript received 27 June 2012; published online 13 August 2012) 
 
The new measuring procedure of nanosized films mechanical characteristics is proposed. The method 
provides laying of an explored material film on a surface of getter which containing gas. A film is locally 
deformed to bubbles formation by gassing from getter. Mechanical properties of nanofilm are calculated by 
measuring the sizes and the shape of the undamaged and destroyed bubbles. Mechanical properties of iron 
nanofilm with thickness 30 nanometers were determined by the method.  
 
Keywords: Nano-Film, Mechanical Properties, Iron, Strain, Getter. 
 
 PACS numbers: 87.15.La, 68.65. – k 
 
 
1. INTRODUCTION 
 
Increasing interest to nano-materials application 
demands knowledge of their mechanical properties. The 
particular interest to measuring of nano-films mechani-
cal properties is due to insufficient suitability of existing 
methods for their precise definition. So, for example, 
accuracy of widely used method of nano-indentation sig-
nificantly depends on substrate material and a thickness 
of an explored film [1]. It also does not allow to define 
tensile strength of a material as material test is made by 
hardness indentation. The purpose of the presented 
work was to get rid of the specified limitation. 
 
2. METHOD AND EXPERIMENT 
 
Procedure is based on betterment of an technique 
for definition of solid thin- and nano-films mechanical 
characteristics [2]. In a method the solid film is super-
imposed on a flat surface of solid getter that contains 
gas. Further, heating of getter results in a gassing. As 
a result there is the partial delamination of a film in 
the form of bubbles. During formation of bubbles there 
is an elastic-plastic deformation ε of a film material. 
Film mechanical properties are computed with use of 
geometrical parameters of bubbles at an elastic-plastic 
state and after removal of elastic strains. Elastic de-
formation removal carry out by gas diffusion through a 
film or as a result of bubbles fracture. Outgassing leads 
to elastic deformation removal. The film residual elon-
gation is conditioned only by a plastic deformation εp. 
Elastic deformation εe is calculated as a difference elas-
tic-plastic and the residual plastic deformation: εe = ε – 
εp. A stress in a film, strength and yield stress of a ma-
terial is calculated as multiplication of a Young's modu-
lus and value of a corresponding elastic strain. Use of a 
Young's modulus for these evaluations is correct be-
cause of insensibility of the given modulus to size ef-
fects [3]. A film state (a) according to the stress-strain 
diagramme (b) is schematically presented on Fig. 1. 
Investigations realized for an iron film nanosized 
thickness. Multilayer structures MgO (7nm)/Fe (30nm) 
was obtained by consecutive electron-beam evaporation 
on polycrystalline substrates SТ51 (based on Al2O3) in 
vacuum 10-4 torr [4]. In such conditions the higher con-
tent of impurities in films, in particular, nitrogen is 
provided. As a result of the forced gassing from getter 
there was a local delamination of explored film Fe and 
formation of numerous bubbles in places of a gas out-
put from getter (Fig. 2). 
 
 
a          b 
 
Fig. 1 – A film state (a) according to the stress-strain dia-
gramme (b): 1 - initial state, a point «0» on the diagramme; 2 - 
tension before a fracturing (a point «E»); 3 - state of a film 
after a relaxation of elastic stresses (a point «D»). 
 
 
Fig. 2 – A film of iron after deposition (a) and after gassing 
from MgO (b) 
 
As is obvious from Fig. 2 bubbles in different diameter 
are observed. Analyzing their shape it is possible to 
define values of elasto-plastic and elastic strains for 
different values of strain. It is possible to define all 
stress-strain diagramme for an investigated material. 
A material strain in bubbles was found from a relation 
of length of arc L of a segment of the strained film of a 
bubble to its chord l. In case of the spherical form of a 
bubbles in altitude h the arc length is defined as 
 
2 2
arctan 4
,where
180 sin(arctan ) 4
l lh
L
l h
,   
 
 
 
50 m 
30 m 
a b 
 A.V. FILATOV, A.E. POGORELOV PROC. NAP 1, 03PCSI15  (2012) 
 
 
03PCSI15 -2 
Table 1 – Mechanical properties of iron 
 
Quantity 
Bulk 
iron 
Iron 
nano-
film 
Whiskers 
of iron 
[5] 
Defectless 
crystal of 
iron [6] 
The limiting 
elastic ex-
tension, % 
0,15 5 5 8  
Strength  
(breaking 
stress), GPa 
0,2-
0,3 
10 13,5 11-18  
 
3. RESULTS AND DISCUSSION 
 
Computing result of mechanical properties of nano-film 
with thickness of 30 nanometers are presented in the 
Table 1. As mechanical properties of bulk materials can 
differ considerably from such for nanosized films due to 
the reduced defect concentration, results of calculations 
compared to mechanical properties of nano-materials, 
such as whiskers of iron [5]. 
As is obvious, the obtained film of iron has mechani-
cal properties, close to that for whiskers of iron [5] and 
for defectless nano-crystals of iron [6]. It is necessary to 
note that the film in bubbles is in planar stressed state. 
It should be take into consideration in the obtained data 
comparison to results of the uniaxial tension [5, 6]. 
 
4. CONCLUSIONS 
 
The technique of mechanical properties determina-
tion for the iron nano-films superimposed on flat getter 
MgO is developed and approved. The obtained results 
show high mechanical strength and elasticity of nano-
films, comparable to properties of defectless nano-
crystals of iron. It can be due to a low defect concentra-
tion of the obtained iron film. 
 
 
REFERENCES 
 
1. W.C. Oliver and G.M. Pharr. J. Mater. Res. 19, 3 (2004) 
2. Palatnik L. S., Ilinsky A.I. Sov. Phys. Uspekhi 95, 616 
(1968). 
3. H. Leidheiser and Billy W. Sloope. J. Appl. Phys. 41, 402 
(1970). 
4. A.V. Filatov, A.E. Pogorelov, Proceedings of 1-st Interna-
tional Conference Nanomaterials «NAP2011» Alushta, 
Crimea, Ukraine Sept. 27-30, 2011, Vol.2, Part I, p.222. 
5. G. Berezhkova, Whiskers (М: 1969). 
6. S. Kotrechko, O. Filatov, O. Ovsjannikov, Mat. Sci. Forum 
567, 65 (2007). 
 


English

Method for Characterization of Nano-Films Mechanical Properties

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 1 No 3, 03PCSI15 (2pp) (2012)   2304-1862/2012/1(3)03PCSI15 (2) 03PCSI15 -1  2012 Sumy State University Method for Characterization of Nano-Films Mechanical Properties  Aleksander V. Filatov, Alexander E. Pogorelov  G.V. Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36, Vernadsky ave., 03142 Kiev, Ukraine  (Received 23 June 2012; revised manuscript received 27 June 2012; published online 13 August 2012)  The new measuring procedure of nanosized films mechanical characteristics is proposed. The method provides laying of an explored material film on a surface of getter which containing gas. A film is locally deformed to bubbles formation by gassing from getter. Mechanical properties of nanofilm are calculated by measuring the sizes and the shape of the undamaged and destroyed bubbles. Mechanical properties of iron nanofilm with thickness 30 nanometers were determined by the method.   Keywords: Nano-Film, Mechanical Properties, Iron, Strain, Getter.   PACS numbers: 87.15.La, 68.65. – k   1. INTRODUCTION  Increasing interest to nano-materials application demands knowledge of their mechanical properties. The particular interest to measuring of nano-films mechani-cal properties is due to insufficient suitability of existing methods for their precise definition. So, for example, accuracy of widely used method of nano-indentation sig-nificantly depends on substrate material and a thickness of an explored film [1]. It also does not allow to define tensile strength of a material as material test is made by hardness indentation. The purpose of the presented work was to get rid of the specified limitation.  2. METHOD AND EXPERIMENT  Procedure is based on betterment of an technique for definition of solid thin- and nano-films mechanical characteristics [2]. In a method the solid film is super-imposed on a flat surface of solid getter that contains gas. Further, heating of getter results in a gassing. As a result there is the partial delamination of a film in the form of bubbles. During formation of bubbles there is an elastic-plastic deformation ε of a film material. Film mechanical properties are computed with use of geometrical parameters of bubbles at an elastic-plastic state and after removal of elastic strains. Elastic de-formation removal carry out by gas diffusion through a film or as a result of bubbles fracture. Outgassing leads to elastic deformation removal. The film residual elon-gation is conditioned only by a plastic deformation εp. Elastic deformation εe is calculated as a difference elas-tic-plastic and the residual plastic deformation: εe = ε – εp. A stress in a film, strength and yield stress of a ma-terial is calculated as multiplication of a Young's modu-lus and value of a corresponding elastic strain. Use of a Young's modulus for these evaluations is correct be-cause of insensibility of the given modulus to size ef-fects [3]. A film state (a) according to the stress-strain diagramme (b) is schematically presented on Fig. 1. Investigations realized for an iron film nanosized thickness. Multilayer structures MgO (7nm)/Fe (30nm) was obtained by consecutive electron-beam evaporation on polycrystalline substrates SТ51 (based on Al2O3) in vacuum 10-4 torr [4]. In such conditions the higher con-tent of impurities in films, in particular, nitrogen is provided. As a result of the forced gassing from getter there was a local delamination of explored film Fe and formation of numerous bubbles in places of a gas out-put from getter (Fig. 2).   a          b  Fig. 1 – A film state (a) according to the stress-strain dia-gramme (b): 1 - initial state, a point «0» on the diagramme; 2 - tension before a fracturing (a point «E»); 3 - state of a film after a relaxation of elastic stresses (a point «D»).   Fig. 2 – A film of iron after deposition (a) and after gassing from MgO (b)  As is obvious from Fig. 2 bubbles in different diameter are observed. Analyzing their shape it is possible to define values of elasto-plastic and elastic strains for different values of strain. It is possible to define all stress-strain diagramme for an investigated material. A material strain in bubbles was found from a relation of length of arc L of a segment of the strained film of a bubble to its chord l. In case of the spherical form of a bubbles in altitude h the arc length is defined as  2 2arctan 4,where180 sin(arctan ) 4l lhLl h,      50 m 30 m a b  A.V. FILATOV, A.E. POGORELOV PROC. NAP 1, 03PCSI15  (2012)   03PCSI15 -2 Table 1 – Mechanical properties of iron  Quantity Bulk iron Iron nano-film Whiskers of iron [5] Defectless crystal of iron [6] The limiting elastic ex-tension, % 0,15 5 5 8  Strength  (breaking stress), GPa 0,2-0,3 10 13,5 11-18   3. RESULTS AND DISCUSSION  Computing result of mechanical properties of nano-film with thickness of 30 nanometers are presented in the Table 1. As mechanical properties of bulk materials can differ considerably from such for nanosized films due to the reduced defect concentration, results of calculations compared to mechanical properties of nano-materials, such as whiskers of iron [5]. As is obvious, the obtained film of iron has mechani-cal properties, close to that for whiskers of iron [5] and for defectless nano-crystals of iron [6]. It is necessary to note that the film in bubbles is in planar stressed state. It should be take into consideration in the obtained data comparison to results of the uniaxial tension [5, 6].  4. CONCLUSIONS  The technique of mechanical properties determina-tion for the iron nano-films superimposed on flat getter MgO is developed and approved. The obtained results show high mechanical strength and elasticity of nano-films, comparable to properties of defectless nano-crystals of iron. It can be due to a low defect concentra-tion of the obtained iron film.   REFERENCES  1. W.C. Oliver and G.M. Pharr. J. Mater. Res. 19, 3 (2004) 2. Palatnik L. S., Ilinsky A.I. Sov. Phys. Uspekhi 95, 616 (1968). 3. H. Leidheiser and Billy W. Sloope. J. Appl. Phys. 41, 402 (1970). 4. A.V. Filatov, A.E. Pogorelov, Proceedings of 1-st Interna-tional Conference Nanomaterials «NAP2011» Alushta, Crimea, Ukraine Sept. 27-30, 2011, Vol.2, Part I, p.222. 5. G. Berezhkova, Whiskers (М: 1969). 6. S. Kotrechko, O. Filatov, O. Ovsjannikov, Mat. Sci. Forum 567, 65 (2007).  

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Method for Characterization of Nano-Films Mechanical Properties

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