Data-Driven Prediction of Grain Boundary Segregation and Disordering in High-Entropy Alloys in a 5D Space

2022 ◽  
Author(s):  
Chongze Hu ◽  
Jian Luo
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Microstructural Evolution ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Data Driven ◽  
High Entropy Alloys ◽  
Materials Properties ◽  
High Entropy ◽  
Fundamental Understanding

Grain boundaries (GBs) can critically influence the microstructural evolution and various materials properties. However, a fundamental understanding of GBs in high-entropy alloys (HEAs) is lacking because of the complex couplings...

Grain boundary segregation in metals

1992 ◽  
Vol 50 (2) ◽  
pp. 1204-1205
Author(s):  
C.L. Briant
Keyword(s):  
Fracture Surface ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Material Properties ◽  
Electron Spectroscopy ◽  
High Vacuum ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Local Concentration ◽  
The One

Grain boundary segregation is the process by which solute elements in a material diffuse to the grain boundaries, become trapped there, and increase their local concentration at the boundary over that in the bulk. As a result of this process this local concentration of the segregant at the grain boundary can be many orders of magnitude greater than the bulk concentration of the segregant. The importance of this problem lies in the fact that grain boundary segregation can affect many material properties such as fracture, corrosion, and grain growth.One of the best ways to study grain boundary segregation is with Auger electron spectroscopy. This spectroscopy is an extremely surface sensitive technique. When it is used to study grain boundary segregation the sample must first be fractured intergranularly in the high vacuum spectrometer. This fracture surface is then the one that is analyzed. The development of scanning Auger spectrometers have allowed researchers to first image the fracture surface that is created and then to perform analyses on individual grain boundaries.

Atomic Scale Characterisation of Electrodeposited Nanocrystalline Ni-P Alloys

1999 ◽  
Vol 581 ◽  
Author(s):  
Matthias Abraham ◽  
Mattias Thuvandert ◽  
Helen M. Lane ◽  
Alfred Cerezo ◽  
George D.W. Smith
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Three Dimensional ◽  
Boundary Segregation ◽  
Atom Probe ◽  
Atomic Scale ◽  
Grain Boundary Segregation ◽  
P Concentration

ABSTRACTNanocrystalline Ni-P alloys produced by electrodeposition have been characterised by three-dimensional atom probe (3DAP) analysis. In the as-deposited materials, there are indications of some variation in P concentration between grains and segregation to grain boundaries. After heat treatment however, strong grain boundary segregation and the formation of Ni3P precipitates have been observed.

Fracture Modes in Ll2 Compounds

1988 ◽  
Vol 133 ◽  
Author(s):  
C. L. Briant ◽  
A. I. Taub
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Intermetallic Compounds ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Fracture Modes ◽  
Beneficial Effects ◽  
Boron Segregation ◽  
Total Composition ◽  
Carbon Additions

ABSTRACTThis paper reports a study of grain boundary segregation and fracture modes in Ll2 intermetallic compounds. Data obtained on Ni3A1, Ni3Si, Ni3Ga, Ni3Ge, and Pt3Ga will be presented. It will be shown that the amount of boron segregation and its ability to improve cohesion depends on the total composition of the compound. The beneficial effects of boron can be counteracted by the presence of borides on the grain boundaries. Carbon additions also produce some improvement in ductility in Ni3Si.

Grain-Boundary Segregation and Phase-Separation Mechanism in Yttria-Stabilized Tetragonal Zirconia Polycrystal

2011 ◽  
Vol 484 ◽  
pp. 82-88
Author(s):  
Koji Matsui ◽  
Hidehiro Yoshida ◽  
Yuichi Ikuhara
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Cubic Phase ◽  
Phase Boundaries ◽  
Transmission Electron ◽  
Sintering Condition

Microstructure development during sintering in 3 mol% Y2O3-stabilized tetragonal ZrO2 polycrystal (Y-TZP) was systematically investigated in two sintering conditions: (a) 1100-1650°C for 2 h and (b) 1300°C for 0-50 h. In the sintering condition (a), the density and grain size in Y-TZP increased with the increasing sintering temperature. Scanning transmission electron microscopy (STEM) and nanoprobe X-ray energy dispersive spectroscopy (EDS) measurements revealed that the Y3+ ion distribution was nearly homogeneous up to 1300°C, i.e., most of grains were the tetragonal phase, but cubic-phase regions with high Y3+ ion concentration were clearly formed in grain interiors adjacent to the grain boundaries at 1500°C. High-resolution transmission electron microscopy (HRTEM) and nanoprobe EDS measurements revealed that no amorphous or second phase is present along the grain-boundary faces, and Y3+ ions segregated not only along the tetragonal-tetragonal phase boundaries but also along tetragonal-cubic phase boundaries over a width below about 10 nm, respectively. These results indicate that the cubic-phase regions are formed from the grain boundaries and/or the multiple junctions in which Y3+ ions segregated. We termed this process a “grain boundary segregation-induced phase transformation (GBSIPT)” mechanism. In the sintering condition (b), the density was low and the grain-growth rate was much slow. In the specimen sintered at 1300°C for 50 h, the cubic-phase regions were clearly formed in the grain interiors adjacent to the grain boundaries. This behavior shows that the cubic-phase regions were formed without grain growth, which can be explained by the GBSIPT model.

Structure And Composition Of Grain Boundaries In SrTiO3

1999 ◽  
Vol 5 (S2) ◽  
pp. 94-95
Author(s):  
O. Kienzle ◽  
F. Ernst ◽  
Manfred Rühle
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Point Defects ◽  
Coincidence Site Lattice ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Boundary Structure ◽  
Dopant Atoms ◽  
Charged Point ◽  
Atomistic Structure

The electrical properties of SrTiO3 (strontium titanate) ceramics are strongly influenced or even dictated by grain boundary segregation of charged point defects, such as dopant atoms, impurities, vacancies, or self-interstitials. The atomistic structure of the grain boundaries, their energy, and the segregation of point defects mutually depend on each other. Grain boundary segregation of charged point defects induces the formation of space charge layers in the adjoining crystals. In order to investigate the relation between grain boundary structure and composition, grain boundaries in Fedoped SrTiO3 bicrystals and in SrTiO3 ceramics were studied by HRTEM and by AEM with subnanometer resolution.Quantitative HRTEM served to investigate the atomistic structure of Σ=3, (111) grain boundaries in Fe-doped SrTiO3 bicrystals with a doping level of Fe/Ti= 0.04at% (Fig. 1). Analysis of the translation state revealed that the Σ=3, (111) grain boundary has an excess volume: normal to the boundary plane, the spacing between the two crystals exceeds what one would expect from a coincidence site lattice model by (0.06 ±0.01 )nm.

Monte Carlo Simulation of Solute-Atom Segregation at Grain Boundaries In Single-Phase Binary Face-Centered Cubic Alloys

1998 ◽  
Vol 4 (S2) ◽  
pp. 764-765
Author(s):  
David N. Seidman ◽  
John D. Rittner ◽  
Dmitry Udler
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Solute Atom ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Diffusional Creep ◽  
Boundary Structure ◽  
Temper Brittleness ◽  
Face Centered Cubic ◽  
Boundary Properties

Solute-atom segregation to grain boundaries has been of interest since the 1930's when it was realized that some steels were susceptible to failure by intergranular fracture when certain impurities were present. Segregation of impurities or intentionally added alloying elements at grain boundaries can greatly affect various grain boundary properties, which in turn affect numerous macroscopic properties. Materials phenomena that have been linked to grain boundary segregation include temper brittleness, fatigue strength, adhesion, precipitation, diffusional creep, intergranular corrosion, and grain boundary diffusivity. Although grain boundary segregation has been extensively studied for many years, the effects of different grain boundary structures on segregation was generally not considered. It has been established both experimentally and theoretically that the level of segregation varies from grain boundary to grain boundary in the same alloy, but there is little direct information on how grain boundary structure influences segregation.

Grain Boundary Segregation-Induced Phase Transformation and Grain Growth in Y2O3-Stabilized ZrO2 Polycrystals

2014 ◽  
Vol 616 ◽  
pp. 8-13
Author(s):  
Koji Matsui ◽  
Hidehiro Yoshida ◽  
Yuichi Ikuhara
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Boundary Segregation ◽  
Growth Behavior ◽  
Grain Boundary Segregation ◽  
Transmission Electron ◽  
Grain Growth Behavior

We systematically investigated the phase transformation and grain-growth behaviors during sintering in 2 and 3 mol% Y2O3-stabilized tetragonal ZrO2 (2Y and 3Y) and 8 mol% Y2O3-stabilized cubic ZrO2 polycrystals (8Y). In particular, grain-boundary segregation and grain-interior distribution of Y3+ ions were examined by high-resolution transmission electron microscopy (HRTEM)- and scanning transmission electron microscopy (STEM)-nanoprobe X-ray energy dispersive spectroscopy (EDS) techniques. Above 1200°C, grain growth during sintering in 8Y was much faster than that in 2Y and 3Y. In the grain boundaries in these specimens, amorphous layers did not present; however, Y3+ ions segregated at the grain boundaries over a width of about 10 nm. The amount of segregated Y3+ ions in 8Y was significantly less than in 2Y and 3Y. This indicates that the amount of segregated Y3+ ions is related to grain growth behavior; i.e., an increase in segregated Y3+ ions retards grain growth. Therefore, grain-growth behavior during sintering can be reasonably explained by the solute-drag mechanism of Y3+ ions segregating along the grain boundary. In 2Y and 3Y, the cubic-phase regions were formed in grain interiors adjacent to the grain boundaries and/or the multiple junctions in which Y3+ ions segregated, which can be explained by a grain boundary segregation-induced phase transformation (GBSIPT) mechanism.

Effect of Isothermal Holding Temperature on NGS Kinetics of Phosphorus and Temper Embrittlement

2007 ◽  
Vol 348-349 ◽  
pp. 549-552
Author(s):  
Jun Wang ◽  
Qing Fen Li ◽  
Er Bao Liu
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Isothermal Holding ◽  
Boundary Segregation ◽  
Temper Embrittlement ◽  
Solution Treatment ◽  
Grain Boundary Segregation ◽  
Solution Temperature ◽  
Kinetics Of ◽  
Holding Temperature

When failure occurs in material, it is often occurs by fracture along some grain boundaries and often by the micro-segregation of embrittling impurity to the grain boundaries. In the present work, the non-equilibrium grain-boundary segregation (NGS) kinetics of phosphorus and the temper embrittlement at the same solution treatment and different isothermal holding temperature in steel 2.25Cr1Mo are studied. The NGS kinetics curves of phosphorus at the same solution temperature （1050 oC ）and different isothermal holding temperature (540 oC and 600 oC) are given. Experimental results provide a direct evidence of NGS kinetic model and show that the grain boundary segregation concentrations of phosphorus for specimen isothermal holding at 540 oC are higher than those at 600 oC. The peak values of AES patterns of solute atoms for specimen isothermal holding at 540 oC are also higher than those at 600 oC. It is therefore concluded that the lower the isothermal holding temperature, the higher the segregation concentration of phosphorus at the grain-boundaries, and also the higher the degree of embrittlement.

Segregation and Phase Transitions in Grain Boundaries

2019 ◽  
Vol 22 ◽  
pp. 160-169
Author(s):  
Boris Bokstein ◽  
Alexey Rodin ◽  
Aleksei Itckovich ◽  
Leonid Klinger
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Computer Modeling ◽  
Boundary Segregation ◽  
Short Description ◽  
Grain Boundary Segregation ◽  
Atomic Interactions

The paper is devoted to some properties of grain boundaries: Segregation and concentration phase transitions – two important consequences of atomic interactions in grain boundaries. Except of a short description the Gibbs method of surface excesses and grain boundary segregation isotherms with the limited number of segregation sites in grain boundary, the paper concentrates on the effects of complexes formation, including thermodynamic and computer modeling, and concentration phase transition in the grain boundaries in systems with restricted solubility and intermediate compounds.

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