Kinetics and Thermodynamics of Amorphous Silicide Formation in Metal/Amorphous-Silicon Multilayer Thin Films

1990 ◽  
Vol 187 ◽  
Author(s):  
C. V. Thompson ◽  
L. A. Clevenger ◽  
R. DeAvillez ◽  
E. Ma ◽  
H. Miura
Keyword(s):  
Amorphous Silicon ◽  
Multilayer Thin Films ◽  
Silicide Formation ◽  
Scanning Calorimetry ◽  
Crystalline Phases ◽  
X Ray ◽  
Calorimetric Measurements ◽  
Transmission Electron ◽  
Amorphous Si ◽  
Original Metal

AbstractFormation of intermetallic phases upon heating of films composed of alternating layers of metal and amorphous silicon has been studied using power-compensated differential scanning calorimetry, crosssectional transmission electron microscopy, and thin film x-ray diffractrometry. Results for Ni/amorphous-Si (Ni/a-Si), Ti/a-Si, V/a- Si, and Co/a-Si are reviewed. In the first three cases, an amorphous silicide is the first phase to form. Further heating leads to thickening of the amorphous silicide and eventually to formation and growth of layers of crystalline silicides. In the case of Co/a-Si multilayer films, a crystalline silicide (CoSi) appears to be the first phase to form. In these systems calorimetric measurements suggest that there are barriers to nucleation of the crystalline phases, even though the energy reduction that would accompany their formation from pure components is large. It is suggested that interdiffusion may precede the formation of new phases at the original metal/a-Si interfaces, resulting in a significant decrease in the driving force for nucleation of the crystalline phases.

Crystallization of Amorphous Si In Al/Si Multilayers

1991 ◽  
Vol 230 ◽  
Author(s):  
Toyohiko J. Konno ◽  
Robert Sinclair
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Layered Structure ◽  
Heat Of Reaction ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Amorphous Si

AbstractThe crystallization of amorphous Si in a Al/Si multilayer (with a modulation length of about 120Å) was investigated using transmission electron microscopy, differential scanning calorimetry and X-ray diffraction. Amorphous Si was found to crystallize at about 175 °C with the heat of reaction of 11±2(kJ/mol). Al grains grow prior to the nucleation of crystalline Si. The crystalline Si was found to nucleate within the grown Al layers. The incipient crystalline Si initially grows within the Al layer and then spreads through the amorphous Si and other Al layers. Because of extensive intermixing, the original layered structure is destroyed. The Al(111) texture is also enhanced.

The kinetics of indium/amorphous-selenium multilayer thin film reactions

1999 ◽  
Vol 14 (3) ◽  
pp. 771-779 ◽  
Author(s):  
K. Lu ◽  
M. L. Sui ◽  
J. H. Perepezko ◽  
B. Lanning
Keyword(s):  
Interface Reaction ◽  
Amorphous Selenium ◽  
Multilayer Thin Films ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Dimensional Growth ◽  
Kinetics Of ◽  
Modulation Wavelength

The reaction kinetics in vapor-deposited indium/amorphous-selenium (a-Se) multilayer thin films were studied using differential scanning calorimetry (DSC), x-ray diffraction (XRD), and transmission electron microscopy (TEM). A number of reactions were observed upon heating with characteristic temperatures which were found to be independent of the multilayer modulation wavelength. The initial interface reaction between In and a-Se is the formation of an In2Se phase. Kinetic analyses of the In2Se formation process combined with TEM observations indicated that interface reaction is characterized by the two-dimensional growth of pre-existing In2Se regions formed during deposition to impingement in the plane of the original In/a-Se interface. The change of the density of In2Se grains with temperature was analyzed in terms of the derived kinetic parameters, which is consistent with TEM observations and the heat release measurements.

Kinetics and Thermodynamics of Amorphous Silicide Formation in Nickel/Amorphous-Silicon Multilayer Thin Films

1989 ◽  
Vol 148 ◽  
Author(s):  
L.A. Clevenger ◽  
C.V. Thompson ◽  
R.R. de Avillez ◽  
K.N. Tu
Keyword(s):  
Thin Films ◽  
Kinetic Analysis ◽  
Amorphous Silicon ◽  
Nickel Silicide ◽  
Multilayer Thin Films ◽  
Silicide Formation ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Kinetic Barriers

ABSTRACTCross-sectional transmission and scanning transmission electron microscopy and thermodynamic and kinetic analysis have been used to characterize amorphous and crystalline nickel silicide formation in nickel/amorphous-silicon multilayer thin films. An amorphous-nickelsilicide layer was formed between the nickel and amorphous-silicon layers during deposition. Heating caused crystalline Ni2Si to form at the nickel/amorphous-nickel-silicide interface. The composition of the amorphous-siicide was determined to be approximately 1 Ni atom to 1 Si atom. Thermodynamic analysis indicates that amorphous-nickel-silicide could be in equilibrium with nickel and amorphous-silicon if there were kinetic barriers to the formation of the crystalline silicides. Kinetic analysis indicates that the “nucleation surface energies” of the crystalline silicides, other than Ni3Si, must be 1.6 to 3.0 times larger than that of amorphous-nickel-silicide.

scholarly journals Effects of Sintering Temperature on Densification, Microstructure and Mechanical Properties of Al-Based Alloy by High-Velocity Compaction

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 218
Author(s):  
Xianjie Yuan ◽  
Xuanhui Qu ◽  
Haiqing Yin ◽  
Zaiqiang Feng ◽  
Mingqi Tang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Velocity ◽  
Sintered Density ◽  
Sintering Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
High Velocity Compaction ◽  
Sintered Temperature

This present work investigates the effects of sintering temperature on densification, mechanical properties and microstructure of Al-based alloy pressed by high-velocity compaction. The green samples were heated under the flow of high pure (99.99 wt%) N2. The heating rate was 4 °C/min before 315 °C. For reducing the residual stress, the samples were isothermally held for one h. Then, the specimens were respectively heated at the rate of 10 °C/min to the temperature between 540 °C and 700 °C, held for one h, and then furnace-cooled to the room temperature. Results indicate that when the sintered temperature was 640 °C, both the sintered density and mechanical properties was optimum. Differential Scanning Calorimetry, X-ray diffraction of sintered samples, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, and Transmission Electron Microscope were used to analyse the microstructure and phases.

Direct Deposition Reactions Between Nickel and Silicon Substrates

1993 ◽  
Vol 311 ◽  
Author(s):  
Lin Zhang ◽  
Douglas G. Ivey
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silicon Substrates ◽  
Silicide Formation ◽  
Cross Sectional ◽  
Deposition Rates ◽  
Plan View ◽  
X Ray ◽  
Si Substrates ◽  
Transmission Electron

ABSTRACTSilicide formation through deposition of Ni onto hot Si substrates has been investigated. Ni was deposited onto <100> oriented Si wafers, which were heated up to 300°C, by e-beam evaporation under a vacuum of <2x10-6 Torr. The deposition rates were varied from 0.1 nm/s to 6 nm/s. The samples were then examined by both cross sectional and plan view transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy and electron diffraction. The experimental results are discussed in terms of a new kinetic model.

Characterization of the Phase Transformations in the Shape Memory Alloy Ni-36 at.% Al

1991 ◽  
Vol 246 ◽  
Author(s):  
J.A. Horton ◽  
E.P. George ◽  
C.J. Sparks ◽  
M.Y. Kao ◽  
O.B. Cavin ◽  
...  
Keyword(s):  
High Temperature ◽  
Shape Memory ◽  
Phase Transformations ◽  
Hot Extrusion ◽  
Exothermic Peak ◽  
Nickel Aluminum ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron

AbstractA survey by differential scanning calorimetry (DSC) and recovery during heating of indentations on a series of nickel-aluminum alloys showed that the Ni-36 at.% Al composition has the best potential for a recoverable shape memory effect at temperatures above 100°C. The phase transformations were studied by high temperature transmission electron microscopy (TEM) and by high temperature x-ray diffraction (HTXRD). Quenching from 1200°C resulted in a single phase, fully martensitic structure. The initial quenched-in martensites were found by both TEM and X-ray diffraction to consist of primarily a body centered tetragonal (bct) phase with some body centered orthorhombic (bco) phase present. On the first heating cycle, DSC showed an endothermic peak at 121°C and an exothermic peak at 289°C, and upon cooling a martensite exothermic peak at 115° C. Upon subsequent cycles the 289°C peak disappeared. High temperature X-ray diffraction, with a heating rate of 2°C/min, showed the expected transformation of bct phase to B2 between 100 and 200°C, however the bco phase remained intact. At 400 to 450°C the B2 phase transformed to Ni2Al and Ni5Al3. During TEM heating experiments a dislocation-free martensite transformed reversibly to B2 at temperatures less than 150°C. At higher temperatures (nearly 600°C) 1/3, 1/3, 1/3 reflections from an ω-like phase formed. Upon cooling, the 1/3, 1/3, 1/3 reflections disappeared and a more complicated martensite resulted. Boron additions suppressed intergranular fracture and, as expected, resulted in no ductility improvements. Boron additions and/or hot extrusion encouraged the formation of a superordered bct structure with 1/2, 1/2, 0 reflections.

Preparation and Property of Al87Ce3Ni8.5Mn1.5 Nanophase Amorphous Composites

2011 ◽  
Vol 412 ◽  
pp. 263-266
Author(s):  
Hong Wei Zhang ◽  
Li Li Zhang ◽  
Feng Rui Zhai ◽  
Jia Jin Tian ◽  
Can Bang Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Phase ◽  
Volume Fraction ◽  
Material Structure ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Different Temperatures

The higher mechanical strength of Al87Ce3Ni8.5Mn1.5 nanophase amorphous composites has been obtained with two methods. The first nanophase amorphous composites are directly produced by the single roller spin quenching technology. The method taken for the second nanophase amorphous composites is at first to obtain amorphous single-phase alloy, followed by annealed at different temperatures .The formative condition, the microstructure, the particle size, the volume fraction of α-Al phase and microhardness of nanophase amorphous composites etc have been investigated and compared by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The microstructure of composites produced by the second method is higher than the former, the fabricated material structure of the system is more uniform and the process is easier to control.

Microstructure Characterization of Si/C Multilayer Thin Films

2013 ◽  
Vol 743-744 ◽  
pp. 910-914
Author(s):  
Ting Han ◽  
Geng Rong Chang ◽  
Yun Jin Sun ◽  
Fei Ma ◽  
Ke Wei Xu
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Multilayer Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Post Annealing ◽  
Transmission Electron ◽  
Twin Defects ◽  
Modulation Ratio

Si/C multilayer thin films were prepared by magnetron sputtering and post-annealing in N2 atmosphere at 1100 for 1h. X-ray diffraction (XRD), Raman scattering and high-resolution transmission electron microscopy (HRTEM) were applied to study the microstructures of the thin films. For the case of Si/C modulation ratio smaller than 1,interlayer diffusion is evident, which promotes the formation of α-SiC during thermal annealing. If the modulation ratio is larger than 1, the Si sublayers are partially crystallized, and the thicker the Si sublayers are, the crystallinity increases. To be excited, brick-shaped nc-Si is directly observed by HRTEM. The brick-shaped nc-Si appears to be more regular near the Si (100) substrate but with twin defects. The results are instructive in the application of solar cells.

Hardness evolution of Al–Cr–N coatings under thermal load

2008 ◽  
Vol 23 (11) ◽  
pp. 2880-2885 ◽  
Author(s):  
Herbert Willmann ◽  
Paul H. Mayrhofer ◽  
Lars Hultman ◽  
Christian Mitterer
Keyword(s):  
Thermal Load ◽  
Structural Changes ◽  
Single Phase ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Al Content ◽  
Annealing Temperatures ◽  
Transmission Electron

Microstructure and hardness evolution of arc-evaporated single-phase cubic Al0.56Cr0.44N and Al0.68Cr0.32N coatings have been investigated after thermal treatment in Ar atmosphere. Based on a combination of differential scanning calorimetry and x-ray diffraction studies, we can conclude that Al0.56Cr0.44N undergoes only small structural changes without any decomposition for annealing temperatures Ta ⩽ 900 °C. Consequently, the hardness decreases only marginally from the as-deposited value of 30.0 ± 1.1 GPa to 29.4 ± 0.9 GPa with Ta increasing to 900 °C, respectively. The film with higher Al content (Al0.68Cr0.32N) exhibits formation of hexagonal (h) AlN at Ta ⩾ 700 °C, which occurs preferably at grain boundaries as identified by analytical transmission electron microscopy. Hence, the hardness increases from the as-deposited value of 30.1 ± 1.3 GPa to 31.6 ± 1.4 GPa with Ta = 725 °C. At higher temperatures, where the size and volume fraction of the h-AlN phase increases, the hardness decreases to 27.5 ± 1.0 GPa with Ta = 900 °C.

Nucleation and Growth of the First Phase in Sputter-Deposited Nb/Al Multilayer Thin Films

1995 ◽  
Vol 398 ◽  
Author(s):  
K. Barmak ◽  
S. Vivekanand ◽  
F. Ma ◽  
C. Michaelsen
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Nucleation And Growth ◽  
Grain Structure ◽  
Multilayer Thin Films ◽  
Product Phase ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Sputter Deposited

ABSTRACTThe formation of the first phase in the reaction of sputter-deposited Nb/Al multilayer thin films has been studied by power-compensated and heat-flux differential scanning calorimetry, x-ray diffraction and transmission electron microscopy. The modulation periods of the films are in the range of 10-500 nm. Both types of calorimetrie measurements, performed at a constant heating rate, show the presence of two peaks (A and B) for the formation of the single product phase, NbAl3. Isothermal calorimetrie scans show that peak A is associated with a nucleation and growth type transformation. The formation of NbAl3 is thus interpreted as a two-stage process of nucleation and lateral growth to coalescence (peak A) followed by normal growth until the consumption of one or both reactants (peak B). Transmission electron microscopy investigations of samples annealed into the first stage of NbAl3 formation show the presence of this phase at the Nb/Al interface and its preferential growth along the grain boundaries of the Al layer. The latter highlights the role of reactant phase grain structure in product phase formation.

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