scholarly journals Metastable phases and macroheterogeneous composites

2021 ◽  
Vol 29 (1) ◽  
pp. 65-68
Author(s):  
O. V. Sukhova
Keyword(s):  
Phase Diagram ◽  
Composite Materials ◽  
Abrasive Wear ◽  
Metastable Phase ◽  
Interfacial Reactions ◽  
Metastable Phases ◽  
Metastable Phase Diagram ◽  
Rapid Dissolution ◽  
Strong Adhesion ◽  
Stable And Metastable Phases

The way to control the interfacial reactions that processes during infiltration of macroheterogeneous composite materials is suggested. The idea is to combine the stable and metastable phases in the filler’s structure which dissolves at a different rate in the molten binder. To prove this approach, the structure and gas-abrasive wear of macroheterogeneous composite materials with Cu–20Ni–20Mn binder reinforced by Fe–(9.0–10.0)B–(0.01-0.2)C filler (in wt. %) cooled at 10–20 K/s or 103–104 K/s are studied. It is shown that the wear resistance of the investigated composite materials can be enhanced by accelerating interfacial reactions between the filler and the molten binder. Therefore, the composite materials produced from a rapidly cooled Fe–B–C filler show a higher resistance to gas-abrasive wear due to formation of Fe–Fe2(B,C) metastable eutectics in its structure. This eutectics crystallizes under metastable phase diagram due to the suppression of stable Fe2(B,C) phase formation and saturation of the rest of liquid by iron in the filler cooled at 103–104 K/s. As a result of rapid dissolution of the eutectics in the molten binder during infiltration, the strong adhesion at the interfaces of the composite materials is achieved which prevents the filler from spalling out under the impacts of abrasive.

scholarly journals Machine Learning the Metastable Phase Diagram of Materials

2021 ◽  
Author(s):  
Srilok Sriniva ◽  
Rohit Batra ◽  
Duan Luo ◽  
Troy Loeffler ◽  
Sukriti Manna ◽  
...  
Keyword(s):  
Machine Learning ◽  
Phase Diagram ◽  
Free Energy ◽  
Phase Diagrams ◽  
First Principles ◽  
Metastable Phase ◽  
Free Energy Calculations ◽  
Metastable Phases ◽  
Metastable Phase Diagram ◽  
Far From Equilibrium

Abstract A central feature of materials synthesis is the concept of phase diagrams. Phase diagrams are an invaluable tool for material synthesis and provide information on the phases of the material at any given thermodynamic condition (i.e., state variables such as pressure, temperature and composition). Conventional phase diagram generation involves experimentation to provide an initial estimate of the set of thermodynamically accessible phases and their boundaries, followed by use of phenomenological models to interpolate between the available experimental data points and extrapolate to experimentally inaccessible regions. Such an approach, combined with high throughput first-principles calculations and data-mining techniques, has led to exhaustive thermodynamic databases (e.g. compatible with the CALPHAD method), albeit focused on the reduced set of phases observed at distinct thermodynamic equilibria. In contrast, materials during their synthesis, operation, or processing, may not reach their thermodynamic equilibrium state but, instead, remain trapped in a local (metastable) free energy minimum, that may exhibit desirable properties. A phase diagram that maps these metastable phases and their thermodynamic behavior is highly desirable but currently lacking, due to the vast configurational landscape. Here, we introduce an automated workflow that integrates first-principles physics and atomistic simulations with machine learning (ML), and high-performance computing to allow rapid exploration of the metastable phases of a given elemental composition and construct "metastable" phase diagrams for materials far-from-equilibrium. Using carbon, a prototypical system with a vast number of metastable phases without parent in equilibrium, we demonstrate automated metastable phase diagram construction to map hundreds of metastable states ranging from near equilibrium to those far-from-equilibrium (400 meV/atom). Moreover, we incorporate the free energy calculations into a neural-network-based learning of the equations of state that allows for efficient construction of metastable phase diagrams. We use the metastable phase diagram and identify domains of relative stability and synthesizability of metastable materials. High temperature high pressure experiments using a diamond anvil cell on graphite sample coupled with high-resolution transmission electron microscopy (HRTEM) confirm our metastable phase predictions. The workflow presented here is general and broadly applicable to single and multi-component systems.

Formation of LuFe2O4 phase from an undercooled LuFeO3 melt in reduced oxygen partial pressure

2008 ◽  
Vol 23 (11) ◽  
pp. 2996-3005 ◽  
Author(s):  
M.S. Vijaya Kumar ◽  
Kazuhiko Kuribayashi ◽  
Koichi Kitazono
Keyword(s):  
Phase Diagram ◽  
Phase Equilibrium ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Metastable Phase ◽  
Bulk Sample ◽  
Metastable Phases ◽  
Ambient Atmosphere ◽  
Metastable Phase Diagram ◽  
Iron Ion

The formation of metastable phases from an undercooled LuFeO3 melt was investigated under reduced Po2 since the iron ion has the tendency to change its valence state from Fe3+ to Fe2+ in an ambient atmosphere with low Po2. The nucleation and the post-recalescence temperatures of the phases were decreased with decreasing process Po2. Phase equilibrium was established in the Lu–Fe–O system at 1473 K by varying the oxygen partial pressure from 105 to 10−1 Pa. A possible ternary metastable phase diagram depending on the oxygen composition in the bulk sample was also constructed. The formation of the LuFe2O4 phase where the Fe3+ and Fe2+ ratio is 1:1 clearly indicated that the formation of metastable phases is related to the presence of Fe2+ ions. Thermogravimetric analysis revealed that the increase in sample mass with decreasing process Po2, down to 10−1 Pa, is relatively dependent on the amount of Fe2+ ions.

Metastable Phase Diagram of Nanocrystalline ZrO2−Sc2O3 Solid Solutions

2009 ◽  
Vol 113 (43) ◽  
pp. 18661-18666 ◽  
Author(s):  
Paula M. Abdala ◽  
Aldo F. Craievich ◽  
Marcia C. A. Fantini ◽  
Marcia L. A. Temperini ◽  
Diego G. Lamas
Keyword(s):  
Phase Diagram ◽  
Solid Solutions ◽  
Metastable Phase ◽  
Metastable Phase Diagram

Stable and Metastable Phase Diagram of the Two-Component System (CH3)3CCl−(CH3)CCl3:  An Example of Crossed Isodimorphism

2001 ◽  
Vol 105 (42) ◽  
pp. 10326-10334 ◽  
Author(s):  
Luis C. Pardo ◽  
María Barrio ◽  
Josep Ll. Tamarit ◽  
Philippe Negrier ◽  
David O. López ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Metastable Phase ◽  
Metastable Phase Diagram ◽  
Two Component System ◽  
Component System ◽  
Two Component

Towards a True Fe-Ni Phase Diagram

1982 ◽  
Vol 21 ◽  
Author(s):  
P L. Rossiter ◽  
R. A Jago
Keyword(s):  
Phase Diagram ◽  
Phase Equilibrium ◽  
Phase Field ◽  
Metastable Phase ◽  
Equilibrium Diagram ◽  
Metastable Phase Diagram ◽  
Iron Meteorites ◽  
Slow Cooling ◽  
Ni Alloys ◽  
True Equilibrium

ABSTRACTA modification to the existing Fe-Ni phase equilibrium diagram is proposed that takes account of the low-temperature ordering reaction to FeNi. It is shown that true equilibrium is never attained during slow cooling of Fe-Ni alloys, even for iron meteorites (which cool extremely slowly). In all real cases, a metastable phase diagram applies, in which the depressed γ/α+γ solvus produces a more extensive γ+ FeNi phase field than for the equilibrium case. This enlarged phase field is used to explain the decomposition of supersaturated Fe-Ni to γ+ FeNi, which is observed only in iron meteorites.

Metastable phase diagram of the PbSn system

1986 ◽  
Vol 78 (2) ◽  
pp. 157-162 ◽  
Author(s):  
K. Mori ◽  
K.N. Ishihara ◽  
P.H. Shinghu
Keyword(s):  
Phase Diagram ◽  
Metastable Phase ◽  
Metastable Phase Diagram
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