Combustion synthesis in the reactive multilayer nanofoils.

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Combustion synthesis in the reactive multilayer
nanofoils.

• H.E.Grigoryan, A.S.Rogachev, I.Yu.Yagubova
• Institute of Structural Macrokinetics and
  materials science RAS, Chernogolovka, Russia

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The scheme of production of multilayer nano-foils
100-4000 layers 5-1000 nm thickness
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Microstructure of foils
? fracture, SEI b surface of the foil,
atomic scanning tunneling microscopy.
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Cross-section of the Ti/Al multilayer film
100 nm
TEM
SEM
1000 nm
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Surface of multilayer film Ti/Al
(Atomic Scanning Tunneling Microscopy)
1 micron
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Main features of the multilayer nanofilm structure

• Continuous layers can be formed with thickness
  from 4 to 1000 nm
• Column lamellar grains appear in all samples
• Multilayer systems possess very attractive
  structure for the study of mechanisms of chemical
  reactions in micro- and nano-heterogeneous systems

Layer boundary
Grain boundary
Close-packed atom planes
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The scheme of experiment
1- sample, 2 mica holder, 3 thin wire, 4
molybdenum heater, 5 steel junction, 6 power
supply, 7 - semiconductor relay, 8 - storage
battery, 9 pulsed-controled oscillator, 10 -
lighter, 11 thermocouple, 12 temperature
registration, 13 - window, 14 vacuum chamber,
15 high-speed video-recorder, 16
photodiode, 17 differential amplifier, 18
PC.
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Experimental setup
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Combustion of Ti/Al multilayer foil Steady mode
T0 200 0?
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Combustion of Ti/Al multilayer foil Non-steady
mode
T0 20 0?
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Combustion of Ti/3Al MLF Spinning combustion
T0 20 0?
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Evidence of oscillating combustion in MLNF Ti/3Al
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Instantaneous velocity for different combustion
modes
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The effect of initial temperature to velocity and
combustion mode
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Temperature profiles of steady and non-steady
combustion wave
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Dependence of combustion velocity on initial
temperature, for different foils and different
type of ignition
1-6 ignition by thin wire 7-11 ignition by
spark 12 literature data for TiAl powder
mixtures Composition TiAl 1 - 2200 layers -
9 nm 2 - 2200 layers - 14 nm 3 - 1350 layers
- 9 nm 4 - 1350 layers - 14 nm 5 - 300 layers
- 70 nm 6 and 10 - 4700 layers 6 nm, 7 - 300
layers 50 nm 8 - 775 layers - 20 nm, 9 - 1350
layers - 9 ??. Composition Ti3Al 11 - 300
layers 60 nm.
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Some features of SHS in the MLNF Ti/Al
Combustion velocity as a function of thickness of
the layers
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Quenched combustion wave in the Ti/3Al MNF
U
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In situ TEM study of heterogeneous reaction and
TiAl product formation
T 600 K
T 700 K
T 900 K
T 1100 K
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Detailed microstructure of reacting Ti/Al MNF
(in situ TEM)
T 1100 K
100 nm
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Laboratoire pour lUtilisation du Rayonnement
Electromagnetique
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Gasless combustion of multilayer nanofilm Ti/Al
(T0420 K)

TiAl(111)
Ti(002)
Ti3Al(?)
TiAl(202)
Al(220)
TiAl(220)
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Gasless combustion of multilayer nanofilm Ti/3Al
TiAl(111)
Ti(002)
TiAl(202)
TiAl(220)
Al(220)
TiAl3(?)
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Phase transformation in multilayer nanofoils
during combustion (part)
Ti/Al
Ti/3Al
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Budker Institute of Nuclear Physics(Novosibirsk
)
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Gasless combustion of multilayer nanofilm Ti/3Al
(time resolution 1ms)
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Scheme of TRSRD experiment
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Structural transformations in multilayer foil
Ti/Al during slow heating (T570 K)
I
II
III
TiAl(111)
Ti(002)
Al(220)
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Structural transformations in multilayer foil
Ti/Al during slow heating (T570 K) stage I,
time step 2 sec
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Structural transformations in multilayer foil
Ti/Al during slow heating (T570 K) stage II,
time step 8 sec
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Thank you for attention!
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Structural transformations in multilayer foil
Ti/Al during slow heating (T570 K) stage III,
time step 4 sec
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Conclusions

• Distribution of local instant velocieties shows
  that the instant value of the combustion
  velocity in multilayer foil never drop down to
  zero, as it frequently happens in powder mixres
• Different kind of combustion waves were observed
• Combustion temperatures for different modes was
  determined
• The mechanism of formation of final product
  phases, TiAl and TiAl3, in the reactive
  multilayer films includes several stages,
  starting from 550 K
• Time-Resolved Synchrotron Radiation Diffraction
  analysis combined with TEM and SEM can provide
  detailed information about reaction routes in
  micro-heterogeneous and nano-heterogeneous
  systems
• - The SHS process in the Ti-AL, Ti-3Al, Ni-Al
  multilayer foils shows an example of the
  quasi-homogeneous gasless comustion

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Structure transformations in multilayer nanofoil
Ti/Al during slow heating (T570 K)
I
II
III
TiAl(111)
Ti(002)
Al(220)
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Critical parameters(LURE)

• Wave-lenght 2,53 ? (4,9 KeV)
• monochromaticity 0,0004
• Intensity 1010 photon/sec
• diffracted area rectangle 0,1 ? 1,5 ??

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Critical parameters(INP)

• Wave-lenght 1,54 ? (4,9 KeV)
• monochromaticity 0,0004
• Intensity 1013 photon/sec
• diffracted area rectangle 1 ? 10 ??

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Coherency of atomic radii and crystal structures
Atom radius, A
Type of structure
Atomic number