Calculation of Gallium-Arsenic-Metal Phase Diagrams

1990 ◽  
Vol 204 ◽  
Author(s):  
James D. Scofield ◽  
J. E. Davison ◽  
S. R. Smith
Keyword(s):  
Free Energy ◽  
Phase Diagrams ◽  
Ternary Alloy ◽  
Regular Solution ◽  
Alloy System ◽  
Energy Functions ◽  
Solid Phases ◽  
Solution Parameters ◽  
Liquid And Solid Phases ◽  
Alloy Systems

ABSTRACTContact metallizations for space-based GaAs solar cells must survive at high temperatures for several minutes. Which metallizations will survive can be predicted by properly calculated phase diagrams instead of performing hundreds of reactions. A method for calculating the ternary temperature constitution phase diagrams Is briefly explained and the phase diagrams are calculated for two Ga-As-X alloy systems. The free energy functions of the liquid and solid phases are approximated by the regular solution theory. The phase diagrams of the three binary alloy systems which form the boundaries of the ternary alloy system are utilized to calculate the binary regular solution parameters. The free energy functions for the ternary liquid and solid phases are expressed In terms of the binary regular solution parameters. The temperature and composition of the liquidus and solidus boundaries for the ternary alloy systems are calculated from these free energy functions. Calculated results are presented for the Ga-As-Ag and the Ga-As-Ge systems.

Thermodynamics of Te80Ge20 − x Pbx glass-forming alloys

1988 ◽  
Vol 3 (3) ◽  
pp. 570-575 ◽  
Author(s):  
L. Battezzati ◽  
A. L. Greer
Keyword(s):  
Free Energy ◽  
Specific Heat ◽  
Glass Forming Ability ◽  
Undercooled Liquid ◽  
Scanning Calorimetry ◽  
Entropy Of Fusion ◽  
Glass Forming ◽  
Crystal Phases ◽  
Solid Phases ◽  
Liquid And Solid Phases

The specific heat of liquid and solid phases and the heats of crystallization and fusion have been measured by differential scanning calorimetry (DSC) for a series of Te80Ge20 − x Pbx alloys (0≤x≤20). The enthalpy, entropy, and free energy of the undercooled liquid are quantitatively assessed with reference to the crystal phases. The available formulas for computing the free energy of the liquid are compared, and their relative merits are discussed. The glass transition temperature is shown to depend strongly on the ratio of the average excess specific heat of the liquid to the entropy of fusion. An anomaly in the liquid specific heat, which is particularly important for Te80Ge20 and Te80Ge15Pb5, leads to very good glass forming ability for these alloys; this is demonstrated by preparing amorphous samples by means of fluxing.

Calculation of the Liquidus and Solidus Surface of Al Rich Corner of Al-Mg-Si Alloy System by ESTPHAD Method

2006 ◽  
Vol 508 ◽  
pp. 635-0
Author(s):  
János Farkas ◽  
András Roósz
Keyword(s):  
Phase Diagrams ◽  
Ternary Alloy ◽  
Liquidus Temperature ◽  
Partition Coefficients ◽  
Equilibrium Phase ◽  
Solidus Surface ◽  
Alloy System ◽  
Data File ◽  
Calphad Method ◽  
Ternary Alloy Systems

A simple but thermodinamically well-founded method is described for the recalculation of liquidus surfaces and partition coefficients of multicomponent equilibrium phase diagrams used a data file of the liquidus temperature and partition coefficients calculated by CALPHAD method. The applicability of the method is shown in case of Al-Mg-Si ternary alloy systems.

scholarly journals Phases and Phase Transitions in the First Few Layers of Methane, Argon and Krypton Adsorbed on Graphite

1992 ◽  
Vol 280 ◽  
Author(s):  
David Goodstein ◽  
P. Day ◽  
M. LaMadrid ◽  
M. Lysek
Keyword(s):  
Phase Transitions ◽  
Phase Diagrams ◽  
Capillary Condensation ◽  
Equilibrium Phase ◽  
Scanning Calorimetry ◽  
Liquid Phases ◽  
Thermodynamic Measurements ◽  
Solid Phases ◽  
Liquid And Solid Phases

ABSTRACTThe equilibrium phase diagrams of monolayers of many substances adsorbed on graphite have long been studied as examples of 2-dimensional (2D) matter. One typically observes 2D gas and liquid phases, and solid phases that may be commensurate or incommensurate with the substrate lattice. Many experimental techniques have been used, but thermodynamic measurements are generally the most useful for tracing out phase boundaries.Recent advances in technique have made it possible to use thermodynamic measurements to study the phase diagrams of the second and higher layers, up to the fifth or sixth. These advances include ultra high resolution scanning calorimetry, and a detailed understanding of the role of capillary condensation in corners and pores of the graphite foam substrate. We find a rich array of phases and phase transitions in multilayer methane, argon and krypton. The second and third layers typically have distinct 2D gas, liquid and solid phases evidenced by 2D triple points and critical points. We observe phase transitions between solid phases that are commensurate and incommensurate with the layer below. We also observe melting of the first layer at higher temperatures, even when one to five additional layers are adsorbed on top of it.In argon and krypton, but not in methane, a strange new phenomenon is observed at temperatures above the gas-liquid critical point of the nth layer for n> 3. Below that temperature, nthlayer gas coexists with a condensed nth layer. At some temperature above it, a new coexistence region is observed in which a partial nth layer coexists with a partial n + 1st layer. This behavior is thought to be evidence for a theoretically predicted phase transition of the bulk interface, called the preroughening transition.

Numerical Study of the Influence of Diffusion-Governed Growth Kinetics of Ternary Alloy on Macrosegregation

2014 ◽  
Vol 790-791 ◽  
pp. 85-90 ◽  
Author(s):  
Meng Huai Wu ◽  
Abdellah Kharicha ◽  
Andreas Ludwig
Keyword(s):  
Ternary Alloy ◽  
Growth Kinetics ◽  
Growth Kinetic ◽  
Numerical Study ◽  
Diffusion Kinetics ◽  
Initial Stage ◽  
Solid Phases ◽  
Kinetics Of ◽  
Liquid And Solid Phases

This article is to assess the modeling treatment of the growth kinetics (finite or infinite diffusion in liquid and solid phases) during solidification and its influence on the calculation of macrosegregation. A model of diffusion-governed growth kinetic for ternary alloy is developed and used for this assessment. Solidification of a 2D casting (50 x 50 mm2) of a ternary alloy (Fe-0.45 wt.% C-1.06 wt.%Mn) is considered. The result shows that finite diffusion in liquid, important for the initial stage of solidification, plays very important role in the formation of macrosegregation. Moreover, the role of the finite diffusion kinetics in the formation of macrosegregation shows differently in the two extreme cases of solidification structures (columnar or equiaxed).

Phase diagrams of ternary alloy systems at high pressure

1993 ◽  
Vol 196 (1-2) ◽  
pp. 229-234 ◽  
Author(s):  
Lizhu Song ◽  
Hua Yang ◽  
Ping Xiao ◽  
Muyu Zhao ◽  
Weiya Zhou ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Diagrams ◽  
Ternary Alloy ◽  
Ternary Alloy Systems ◽  
Alloy Systems

Inspection of free energy functions in gradient crystal plasticity

2013 ◽  
Vol 29 (6) ◽  
pp. 763-772 ◽  
Author(s):  
Samuel Forest ◽  
Nicolas Guéninchault
Keyword(s):  
Free Energy ◽  
Crystal Plasticity ◽  
Energy Functions

Complex investigation of the thermal and electrophysical properties of refractory oxides in the liquid and solid phases

1980 ◽  
Vol 38 (4) ◽  
pp. 333-337
Author(s):  
�. �. Shpil'rain ◽  
D. N. Kagan ◽  
L. S. Barkhatov ◽  
L. I. Zhmakin ◽  
V. V. Koroleva
Keyword(s):  
Electrophysical Properties ◽  
Complex Investigation ◽  
Refractory Oxides ◽  
Solid Phases ◽  
Liquid And Solid Phases
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