Thermodynamic Analysis for the Solid-State Amorphization and Subsequent Crystallization of GaAs/Co

1991 ◽  
Vol 230 ◽  
Author(s):  
F.-Y. Shiau ◽  
S.-L. Chen ◽  
M. Loomans ◽  
Y. A. Chang
Keyword(s):  
Phase Diagram ◽  
Solid State ◽  
Liquid Phase ◽  
Gibbs Energy ◽  
Phase Equilibria ◽  
Amorphous Phase ◽  
Thermodynamic Analysis ◽  
Supercooled Liquid ◽  
State Amorphization

AbstractPhase equilibria along the CoGa-CoAs join were determined by DTA and metallography. On the basis of these data and the phase diagram of Co-Ga-As at 600 °C, thermodynamic values for the various phases along the GaAs-Co join were estimated. The Gibbs energy of the amorphous phase is approximated to be that of the supercooled liquid phase. These data were used to rationalize the amorphization process.

Solid state amorphization reactions in deformed Ni-Zr multilayered composites

1990 ◽  
Vol 5 (3) ◽  
pp. 488-497 ◽  
Author(s):  
G. C. Wong ◽  
W. L. Johnson ◽  
E. J. Cotts
Keyword(s):  
Thermal Stability ◽  
Solid State ◽  
Amorphous Phase ◽  
Equilibrium Phase ◽  
Solid State Reactions ◽  
Heat Of Mixing ◽  
Scanning Calorimetry ◽  
Multilayered Composites ◽  
State Amorphization ◽  
Thermal Stability Of

The mechanisms of metallic glass formation and competing crystallization processes in mechanically-deformed Ni-Zr multilayered composites have been investigated by means of differential scanning calorimetry and x-ray diffraction. Our investigation of the heat of formation of amorphous NixZr1−x alloys shows a large negative heat of mixing (on the order of 30 kJ/mole) for compositions near Zr55Ni45 with a compositional dependence qualitatively similar to that predicted by mean field theory. We find that the products of solid state reactions in composites of Ni and Zr can be better understood in terms of the equilibrium phase diagram and the thermal stability of liquid quenched metallic glasses. We have determined the composition of the growing amorphous phase at the Zr interface in these Ni-Zr diffusion couples to be 55 ± 4% Zr. We investigated the kinetics of solid state reactions competing with the solid state amorphization reaction and found the value of the activation energy of the initial crystallization and growth of the growing amorphous phase to be 2.0 ± 0.1 eV, establishing an upper limit on the thermal stability of the growing amorphous phase.

Calphad description of the Ge-Mn system

2014 ◽  
Vol 1642 ◽  
Author(s):  
Alexandre Berche ◽  
Jean-Claude Tédenac ◽  
Philippe Jund ◽  
Stéphane Gorsse
Keyword(s):  
Phase Diagram ◽  
Liquid Phase ◽  
Thermodynamic Properties ◽  
Gibbs Energy ◽  
Critical Review ◽  
Thermodynamic Description ◽  
Calphad Method ◽  
Review Of The Literature ◽  
Solid Phases

ABSTRACTThe germanium-manganese system has been experimentally studied but no Calphad description is available yet. After a critical review of the literature concerning the phase diagram and the thermodynamic properties, a thermodynamic description of the Gibbs energy of the phases is performed using the Calphad method. The liquid phase is described with an associated model and the variation to the stoichiometry of the solid phases is taken into account.

On the role of diffusion in phase selection during reactions at interfaces

1992 ◽  
Vol 7 (2) ◽  
pp. 367-373 ◽  
Author(s):  
C.V. Thompson
Keyword(s):  
Solid State ◽  
Thermodynamic Analysis ◽  
Phase Formation ◽  
Phase Selection ◽  
Transient Nucleation ◽  
State Amorphization

It is argued that interdiffusion must precede nucleation of new phases during reactions at interfaces between compositionally different phases. The relative rates at which elemental components diffuse in the reacting phases control the sequence in which phases can form, and can also strongly affect the relative nucleation rates of alloy products, especially in the transient nucleation regime. While detailed predictions of the relative nucleation rates require usually unavailable knowledge of the energies of the relevant interfaces, in some cases, knowledge of the relevant diffusivities, along with a thermodynamic analysis, can lead to predictions of likely phase formation sequences. These concepts are used to explain the association of diffusional asymmetry with systems that undergo solid state amorphization, and to specify semiquantitatively the degree of asymmetry required for solid state amorphization.

High resolution studies of the solid state amorphization reaction in the ZrCo system with the atom probe/field ion microscope

1994 ◽  
Vol 343 ◽  
Author(s):  
Susanne Schneider ◽  
Ralf Busch ◽  
Konrad Samwer
Keyword(s):  
Solid State ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Amorphous Phase ◽  
Rutherford Backscattering Spectrometry ◽  
Atom Probe ◽  
Nanometer Scale ◽  
Probe Field ◽  
Field Ion Microscope ◽  
State Amorphization

ABSTRACTThe atom probe/field ion microscope is introduced as a new powerful investigation device to study the early stages of the solid state amorphization reaction (SSAR). A bilayer of Zr and Co was condensed under UHV conditions on W wire tips and analyzed in a field ion microscope (FIM) combined with an atom probe (AP). The reaction of Co with Zr has been studied at room temperature. FIM pictures and AP analysis have shown that even at low temperatures an amorphous phase is formed at the Zr/Co interface and in the Zr grain boundaries. In these areas concentration profiles have been taken on a nanometer scale. Most likely, the extended solid solution of Co found in α- Zr grain boundaries causes the formation of the amorphous phase. Further, Rutherford backscattering spectrometry (RBS) suggests that even point defects and dislocations at the surface of an α- Zr single crystal are sufficient to initiate the SSAR between a polycrystalline Co layer vapour- deposited onto that single crystal.

Phase Diagram Relationships in the Ternary System Ti-Ai-V

1990 ◽  
Vol 213 ◽  
Author(s):  
Mohan Paruchuri ◽  
T.B. Massalski
Keyword(s):  
Phase Diagram ◽  
Isothermal Section ◽  
Solid State ◽  
Ternary System ◽  
Phase Equilibria ◽  
Liquidus Surface ◽  
Experimental Techniques

ABSTRACTLiquid-solid and solid state phase equilibria in the ternary system Ti-Al-V have been studied using a combination of several experimental techniques. A likely surface of primary seperation (i.e., the liquidus surface) is proposed in the form of the usual projection on the triangular base and the directions of the monovariant lines are defined. Four ternary invariant reactions have been identified in this system. Solid state equilibria have been determined at 900°C and are presented in the form of an isothermal section through the phase diagram. These are very similar to the relationships reported at 800°C by Hashimoto et al. [1].

Metastable phase equilibria and solid state amorphization

1988 ◽  
Vol 140 ◽  
pp. 287-297 ◽  
Author(s):  
J.H. Perepezko ◽  
Y.A. Chang ◽  
H.J. Fecht ◽  
M.X. Zhang
Keyword(s):  
Solid State ◽  
Phase Equilibria ◽  
Metastable Phase ◽  
State Amorphization

Amorphous-phase formation and initial reactions at Pt/GaAs interfaces

1991 ◽  
Vol 49 ◽  
pp. 858-859
Author(s):  
Dae-Hong Ko ◽  
Robert Sinclair
Keyword(s):  
Solid State ◽  
Amorphous Phase ◽  
Phase Formation ◽  
Compound Semiconductor ◽  
Metal Compound ◽  
Heat Of Mixing ◽  
Semiconductor Interface ◽  
Direct Demonstration ◽  
State Amorphization ◽  
Amorphous Phase Formation

It is now well known that many metals form a l-2nm amorphous interdiffused layer when deposited onto clean Si surface, which grows upon annealing in some systems but crystallizes into stable, or metastable, phases in others. Such behavior can be interpreted in terms of a solid-state amorphization, driven by a negative heat of mixing of the elements with the amorphous phase produced for kinetic reasons. Some metal/compound semiconductor systems also show the same reaction behavior. Though there have been some reports, using electron diffraction, on the amorphous phase formation at metal-compound semiconductor interface upon low temperature annealing, because the expected thickness might only be several atomic layers, it is clear that high resolution transmission electron microscopy (HRTEM) is the most powerful technique to study such a phase. This article reports on the amorphous phase formation and the initial stages of reaction occuring at Pt/GaAs interfaces upon annealing with HRTEM, and this is the most direct demonstration of solid state amorphization of a metal with a compound semiconductor.

scholarly journals Interdependence of stress and interdiffusion during solid-state amorphization in Ni–Hf

2000 ◽  
Vol 15 (2) ◽  
pp. 463-475 ◽  
Author(s):  
W. S. L. Boyer ◽  
M. Atzmon
Keyword(s):  
Solid State ◽  
Tensile Stress ◽  
Diffusion Couple ◽  
Amorphous Phase ◽  
Ion Irradiation ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Curvature Measurements ◽  
Stress Variations ◽  
State Amorphization

The evolution of stress in a Ni–Hf diffusion couple during solid-state amorphization reaction has been monitored by substrate curvature measurements and x-ray diffraction. The latter technique allowed an independent determination of the contribution of changes in stress-free lattice parameter to the stress in the crystalline layers. The results indicate that the amorphous phase forms under a large tensile stress, which relaxes as the reaction progresses. This stress in the amorphous phase is consistent with the volume change associated with the reaction. Stresses in the crystalline, elemental phases are considerably smaller and not affected by the reaction. Low-temperature Ni ion irradiation increases the tensile stress in the diffusion couple. The large observed stress variations are not accompanied by variations in the effective interdiffusion coefficient.

Solid-state phase equilibria in the Mg corner of the MgGdSm phase diagram

1996 ◽  
Vol 239 (2) ◽  
pp. 209-213 ◽  
Author(s):  
L.L. Rokhlin ◽  
N.I. Nikitina ◽  
T.V. Dobatkina
Keyword(s):  
Phase Diagram ◽  
Solid State ◽  
Phase Equilibria
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