MODELING MESOSCALE DYNAMICS OF FORMATION OF δ′-PHASE IN Al-Li ALLOYS

1993 ◽  
Vol 07 (16) ◽  
pp. 1083-1094
Author(s):  
R.S. GOLDSTEIN ◽  
M.F. ZIMMER ◽  
Y. OONO
Keyword(s):  
Minimal Model ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
Phase System ◽  
Two Phase ◽  
Mesoscale Dynamics ◽  
Model Free ◽  
Model Study ◽  
Δ Phase ◽  
Ordered State

A mesoscale minimal model study of the α−δ′ two-phase system is presented. A minimal model free energy is introduced which reveals universal features of the ordering dynamics of the disordered into the L1 2 ordered state. Static phenomenological parameters of the minimal model are chosen to reproduce the equilibrium phase diagram, and dynamical ones are chosen to reproduce recent experimental scattering results by H. Chen’s group.

A Morphology of Diffusion Zone from Entropy Production Calculations

2014 ◽  
Vol 1 ◽  
pp. 31-45 ◽  
Author(s):  
M. Danielewski ◽  
B. Wierzba ◽  
K. Tkacz-Śmiech
Keyword(s):  
Diffusion Zone ◽  
Initial Conditions ◽  
Equilibrium Phase ◽  
Diffusion Path ◽  
Alloy Coating ◽  
Equilibrium Phase Diagram ◽  
Advanced Materials ◽  
Two Phase ◽  
Three Phase ◽  
Phase Layers

Interdiffusion plays a significant role in the formation and stability of metallic joints and coatings. It is also of critical importance in designing advanced materials. Because commercial alloys are usually multicomponent, the key target is prediction of a complex morphology of the diffusion zone which grows between the alloys, alloy-coating, etc. In a two-component system, the diffusion zone can be composed of single-phase layers of the intermetallic compounds and solid solutions. The evolution of the composition and thicknesses of such layers are fairly well understood and consistent with the phase diagrams. The situation is qualitatively different in multicomponent systems. For example, the diffusion zone in a ternary system can be composed of single-and two-phase sublayers. Their number and thicknesses depend on the initial conditions, i.e. composition, component diffusivities and geometry of the system. The usual way of presenting the sequence of the layers and their compositions is by drawingadiffusionpathwhich is, by definition,a mapping of thestationary concentrations onto the isothermal section of the equilibrium phase diagram. The diffusion path connects initial compositions of the diffusion couple and can go across the single-, two-and three-phase fields. It starts at the composition of one alloy and ends at the other. The possibility of mapping the concentration profiles onto the ternary isotherm has been postulated in one from the seventeen theorems by Kirkaldy and Brown [] for the diffusion path. The detailed presentation of all theorems was recently done by Morral []. Here we remind the reader only of the chosen ones (shown in italics).

scholarly journals A magnetic study of the two-phase iron-nickel alloys

1940 ◽  
Vol 175 (962) ◽  
pp. 331-344 ◽  
Keyword(s):  
Thermal Hysteresis ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
Two Phase ◽  
Saturation Intensity ◽  
Visual Evidence ◽  
Magnetic Investigation ◽  
Iron Nickel ◽  
Lower Temperature ◽  
Iron Nickel Alloys

The iron-rich alloys of iron and nickel resemble pure iron in that they undergo a phase change from body-centred cubic ( α ) structure to face-centred cubic ( γ ) structure on heating. On cooling the alloys, however, the return to the original state takes place at a much lower temperature, and on account of this thermal hysteresis the alloys are known as irreversible. A magnetic investigation of these alloys has been made by Peschard (1925), who measured the variation of the saturation intensity of the alloys with temperature. The change from the α to the γ lattice is accompanied by a decrease of the saturation intensity of the alloy, since the γ phase is non-magnetic at the temperature of the change. Curves showing the variation of intensity with temperature are very useful in the study of these alloys, since they give visual evidence of the irreversibility. The relation of the irreversible changes to the equilibrium phase diagram is not clearly understood. Recently, however, equilibrium diagrams of the iron-nickel system, determined by means of X-ray data, have been published by Bradley and Goldschmidt (1939) and Owen and Sully (1939).

scholarly journals Opportunities in Plutonium Metallurgical Research*

2006 ◽  
Vol 986 ◽  
Author(s):  
Adam J. Schwartz
Keyword(s):  
Materials Science ◽  
Phonon Dispersion ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
Phonon Dispersion Curves ◽  
The Past ◽  
Tremendous Progress ◽  
Δ Phase ◽  
Substantial Progress ◽  
Exciting Time

AbstractThis is an exciting time to be involved in plutonium metallurgical research. Over the past few years, there have been significant advances in our understanding of the fundamental materials science of this unusual metal, particularly in the areas of self-irradiation induced aging of Pu, the equilibrium phase diagram, the homogenization of δ-phase alloys, the crystallography and morphology of the α'-phase resulting from the isothermal martensitic phase transformation, and the phonon dispersion curves, among many others. In addition, tremendous progress has been made, both experimentally and theoretically, in our understanding of the condensed matter physics and chemistry of the actinides, particularly in the area of electronic structure. Although these communities have made substantial progress, many challenges still remain. This brief overview will address a number of important challenges that we face in fully comprehending the metallurgy of Pu with a specific focus on aging and phase transformations.

Can Amortization Bs Induced by Ion Mixing in Ag-Cu and Ag-Ni Systems?

1985 ◽  
Vol 54 ◽  
Author(s):  
B. X. Liu ◽  
L. J. Huang ◽  
J. Li ◽  
S. Ma
Keyword(s):  
Phase Diagram ◽  
Amorphous Phase ◽  
Equilibrium Phase ◽  
Structural Difference ◽  
Liquid Nitrogen Temperature ◽  
Equilibrium Phase Diagram ◽  
Heat Of Formation ◽  
Phase Region ◽  
Two Phase ◽  
Amorphous Phase Formation

ABSTRACTThe extended Structural Difference Rule for amorphous phase formation states that an amorphous phase can be obtained by ion mixing with an alloy with a composition lying in a two-phase region in the equilibrium phase diagram. This criterion has to respond to the challenge that no amorphous alloy has been formed in some early studied systems exhibiting a two-phase region character, e.g. Ag-Cu(typical eutec-tic),Ag-Ni(almost entirely immiscible),etc‥We performed ion mixing experiments for several systems at liquid nitrogen temperature using Xe ions with low current density. Amorphization was indeed observed in both Ag-Cu and Ag-Ni samples, as two halos were seen by TEM SAD immediately after adequate doses ion mixing. These not only support our two-pnase region rule, but also show the possibility of amorphization in a system(Ag-Ni) that has large positive heat of formation.

scholarly journals Thermal Decomposition of Olive-Mill Byproducts: A TG-FTIR Approach

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4123
Author(s):  
Małgorzata Wzorek ◽  
Robert Junga ◽  
Ersel Yilmaz ◽  
Bohdan Bozhenko
Keyword(s):  
Isoconversional Methods ◽  
Phase System ◽  
Heating Rates ◽  
Two Phase ◽  
Model Free ◽  
Three Phase ◽  
Different Types ◽  
Temperature Ranges ◽  
Ftir Technique ◽  
Olive Mill

In this study, the combustion of olive byproducts was investigated using the TG-FTIR technique. Different types of olive biomass were considered: twigs, leaves, olive-mill waste from the two-phase decanting method, and wastewater from the three-phase system. The reaction regions, ignition, and burnout temperatures at different heating rates were determined using TG/DTG analysis and the thermogravimetry results. Comprehensive combustion, ignition, burnout, and flammability indexes were also calculated. The highest combustion index values were obtained for waste from the three-phase system, followed by the two-phase decanting method, then with leaves and small twigs. The order of the index values indicated that the sample from the three-phase process ignited more quickly and yielded faster. The changes in activation energy calculated using different model-free isoconversional methods—Friedman, Ozawa–Flynn–Wall, and Kissinger–Akahira–Sunose—fell within the range of 130–140 kJ/kmol. FTIR analyses presented differences in the exhaust gas composition for specific combustion temperature ranges.

Calculation of the Mg-Gd-Y Alloy Equilibrium Phase Diagram and its Verification at 450°C

2013 ◽  
Vol 275-277 ◽  
pp. 1896-1903
Author(s):  
Yong Chun Guo ◽  
Ying Ming Sang ◽  
Jian Ping Li ◽  
Zhong Yang
Keyword(s):  
Phase Diagram ◽  
Phase Equilibrium ◽  
Diffusion Layer ◽  
Single Phase ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
Atomic Diffusion ◽  
Diffusion Couples ◽  
Equilibrium Calculation ◽  
Two Phase

The Mg-Gd alloy, Mg-Y alloy equilibrium phase diagram has been characterized using the multiple phase equilibrium calculation software (Pandat) and the magnesium alloy thermodynamic database. The Mg-Gd and Mg-Y diffusion couples were made by the rivet method. According to the local balance principle, these diffusion couples were processed using an equalization treatment at 450 °C, followed by EDS analysis with a scanning electron microscope. The results show that a concentration gradient resulting from atomic diffusion is apparent in the Mg-Y and Mg-Gd diffusion layer, showing that the diffusion layers belong to different phases. There are 5 two-phase regions and 2 single phase regions in the Mg-Gd diffusion layer and 4 two-phase regions and 2 single phase regions in the Mg-Y diffusion layer. These results are consistent with the data from the phase equilibrium calculation. This research can provide experimental support for the Mg-Gd-Y three element alloy phase diagram calculation.

Equilibrium phase behavior of aqueous two-phase system formed by triblock copolymer + sulfate salt + water at different temperatures

2018 ◽  
Vol 478 ◽  
pp. 145-152 ◽  
Author(s):  
Laryssa Fernanda da Silva Gonçalves ◽  
Nehander Carlos Mendes Felizberto ◽  
Keycianne da Cruz Silva ◽  
Aparecida Barbosa Mageste ◽  
Guilherme Dias Rodrigues ◽  
...  
Keyword(s):  
Phase Behavior ◽  
Triblock Copolymer ◽  
Salt Water ◽  
Equilibrium Phase ◽  
Phase System ◽  
Sulfate Salt ◽  
Two Phase ◽  
Aqueous Two Phase System ◽  
Different Temperatures

On the Problem of “Two-Phase” Activated Sludge

1991 ◽  
Vol 24 (7) ◽  
pp. 59-64 ◽  
Author(s):  
R. W. Szetela
Keyword(s):  
Activated Sludge ◽  
Single Phase ◽  
Phase System ◽  
Two Phase ◽  
Wastewater Treatment Process ◽  
Sludge Stabilization ◽  
Technological Advantage ◽  
In Series ◽  
State Models ◽  
Activated Sludge Systems

Steady-state models are presented to describe the wastewater treatment process in two activated sludge systems. One of these makes use of a single complete-mix reactor; the other one involves two complete-mix reactors arranged in series. The in-series system is equivalent to what is known as the “two-phase” activated sludge, a concept which is now being launched throughout Poland in conjunction with the PROMLECZ technology under implementation. Analysis of the mathematical models has revealed the following: (1) treatment efficiency, excess sludge production, energy consumption, and the degree of sludge stabilization are identical in the two systems; (2) there exists a technological equivalence of “two-phase” sludge with “single-phase” sludge; (3) the “two-phase” system has no technological advantage over the “single-phase” system.

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