The Precipitation of Nickel and Copper at Grain Boundaries in Silicon

1990 ◽  
Vol 209 ◽  
Author(s):  
H. J. Möller ◽  
U. Jendrich ◽  
L. Huang ◽  
A. Foitzik
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Cooling Rate ◽  
Point Defects ◽  
Polycrystalline Silicon ◽  
Three Dimensional ◽  
Surface Source ◽  
Native Point Defects ◽  
Micrometer Size

ABSTRACTThe precipitation of copper and nickel at grain boundaries in cast polycrystalline silicon is investigated. The metals are diffused into the specimens from a surface source between 800 – 1000 °C and the precipitation after cooling is studied by TEM. Copper precipitates in form of colonies containing hundreds of particles with a size between 5–6 nm. In the grain boundary they nucleate preferentially at dislocations and steps. The distribution and size of the precipitates depend on the cooling rate after the diffusion. Nickel forms only few large (micrometer size) plate-like or three dimensional precipitates at and near grain boundaries. The main features of the results and the differences between the two elements are explained under the assumption that the precipitation requires the transport of native point defects.

Precipitation of Copper and Cobalt at Grain Boundaries in Silicon

1989 ◽  
Vol 163 ◽  
Author(s):  
U. Jendrich ◽  
H. J. Möller
Keyword(s):  
Particle Size ◽  
Mössbauer Spectroscopy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Cooling Rate ◽  
Polycrystalline Silicon ◽  
Mossbauer Spectroscopy ◽  
Low Energy ◽  
Surface Source ◽  
Mößbauer Spectroscopy

AbstractThe precipitation of copper and (radioactive) cobalt at low energy grain boundaries in polycrystalline silicon and bicrystals is investigated. The metals are diffused in from a surface source between 800 - 1000 °C and the precipitation after cooling down is studied by TEM (for Cu) and Mößbauer spectroscopy (for Co). The precipitates are metal suicides. For copper it is shown that they appear in form of colonies containing hundreds of precipitates with a particle size between 5-60 nm. In the grain boundary they nucleate preferentially at dislocations and steps. The distribution and size of the precipitates depend on the cooling rate after the diffusion. In the vicinity of the grain boundary the volume is depleted from the impurities.

TEM and HREM Investigation of The Precipitation of Cobalt and Nickel In Polycrystalline Silicon

1991 ◽  
Vol 238 ◽  
Author(s):  
H. J. Möller ◽  
Juyong Chung ◽  
Lan Huang
Keyword(s):  
Grain Boundaries ◽  
Lattice Mismatch ◽  
Large Angle ◽  
Three Dimensional ◽  
Cobalt Disilicide ◽  
Surface Source ◽  
High Resolution Tem ◽  
Nickel Disilicide ◽  
Micrometer Size ◽  
Cobalt And Nickel

ABSTRACTThe precipitation behavior of cobalt and nickel at grain boundaries in multicrystalline silicon is investigated. The metals are diffused into the specimens from a surface source between 800 -1000 °C and the precipitation after cooling is studied by conventional and high resolution TEM. Cobalt and nickel disilicide precipitates nucleate both in the bulk and at grain boundaries. They form few large (micrometer size) plate-like or three-dimensional precipitates depending on the cooling rate. Cobalt disilicide with a slightly larger lattice mismatch has a higher tendency to nucleate at large angle grain boundaries. Both suicides nucleate preferentially at coherent twin boundaries forming a few atomic layers thick platelet parallel to the {111} twin plane. HREM and image simulations are performed to analyze the Si / MS12 / twin interface structure (M = Co, Ni).

Grain Boundary-Dependent Selection Criteria for Nucleation of Gamma-Massive Grains in TiAl-Based Alloys

2010 ◽  
Vol 654-656 ◽  
pp. 2338-2341 ◽  
Author(s):  
A. Sankaran ◽  
Emmanuel Bouzy ◽  
Matthew R. Barnett ◽  
Alain Hazotte
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Selection Criteria ◽  
Three Dimensional ◽  
Massive Transformation ◽  
Three Dimensions ◽  
Variant Selection ◽  
Electron Backscattered Diffraction ◽  
Resolution Electron ◽  
Nucleation Mechanisms

Rapid cooling of TiAl-based alloy from α phase (disordered hexagonal, A3) generates  phase (ordered tetragonal, L1o) grains through massive transformation nucleating mostly over the α/α grain boundaries. This current work deals with the identification and the validation of different nucleation mechanisms during  massive transformation in TiAl-based alloys. Special attention has been given to the variant selection criteria for the nucleation of the massive structures along different types of α/α grain boundaries. The  massive domains formed along the grain boundaries were analysed using high resolution electron backscattered diffraction (EBSD). Statistical studies were made on different nucleation sites and different mechanisms are proposed. Two–dimensional studies of the nucleation mechanism suggest that the minimization of the interfacial energy could be the predominant criteria during the grain boundary nucleation. In order to verify this nucleation criterion in three-dimensions, serial sections were made and EBSD maps were taken and analysed in each section. The variant selection observed during the nucleation and the growth of the  massive grains is further discussed after getting a broader view under three-dimensional investigations.

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.

Effect of Grain Boundary Characteristics on Lattice Orientations

2007 ◽  
Vol 26-28 ◽  
pp. 1003-1006 ◽  
Author(s):  
Jae Hyung Cho
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Three Dimensional ◽  
Microstructural Characterization ◽  
Grain Boundary Character Distribution ◽  
Average Scheme ◽  
Plane Normal ◽  
Grain Boundary Characteristics ◽  
Correlation Parameters ◽  
Boundary Characteristics

Grain boundary characteristics are defined by five parameter, grain boundary plane normal and misorientation angle/axis between two adjacent grains. The influence of the grain boundary character distribution on lattice evolution during deformation was investigated using three-dimensional crystal plasticity finite element method (CPFEM). Various combinations of grain boundaries were modeled systematically. In analyzing the numerical microstructural characterization obtained by the simulation, orientation average scheme and correlation parameters between misorientation and its special distribution are used. Inter- and intra-grain structures were investigated using the spatial distribution of lattice orientation. Main emphasis was placed on misorientation distributions around grain boundaries, where grain interaction mainly occurred.

Advantages of MIS Processing on Passivated Polycrystalline Silicon

1981 ◽  
Vol 5 ◽  
Author(s):  
G. Rajeswaran ◽  
M. Thayer ◽  
V. J. Rao ◽  
W. A. Anderson
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Polycrystalline Silicon ◽  
Hydrogen Plasma ◽  
Mis Structures

ABSTRACTWacker polycrystalline silicon shows enhanced grain boundary activity after a high temperature (950° C) anneal. It is possible to passivate this effect in a hydrogen plasma. The low temperature (600° C) processing of MIS technology does not activate grain boundaries or deteriorate a passivated specimen. Activated grain boundaries with MIS structures can be used to assess the character of recombination currents. It is concluded that MIS processing is advantageous for passivated polycrystalline silicon.

Influence of Grain Boundary Mobility on Microstructure Evolution during Recrystallisation

2012 ◽  
Vol 715-716 ◽  
pp. 191-196
Author(s):  
Myrjam Winning ◽  
Dierk Raabe
Keyword(s):  
Grain Boundary ◽  
Cellular Automaton ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Microstructure Evolution ◽  
Texture Evolution ◽  
Three Dimensional ◽  
Boundary Mobility ◽  
Metallic Materials ◽  
Grain Boundary Mobility

The paper introduces first investigations on how low angle grain boundaries can influence the recrystallisation behaviour of crystalline metallic materials. For this purpose a three-dimensional cellular automaton model was used. The approach in this study is to allow even low angle grain boundaries to move during recrystallisation. The effect of this non-zero mobility of low angle grain boundaries will be analysed for the recrystallisation of deformed Al single crystals with Cube orientation. It will be shown that low angle grain boundaries indeed influence the kinetics as well as the texture evolution of metallic materials during recrystallisation.

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.

Room Temperature Tensile Ductility in Powder Processed B2 FeAi Alloys

1986 ◽  
Vol 81 ◽  
Author(s):  
M. A. Crimp ◽  
K. M. Vedula ◽  
D. J. Gaydosh
Keyword(s):  
Fracture Surface ◽  
Yield Strength ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Cooling Rate ◽  
Yield Stress ◽  
Room Temperature ◽  
Tensile Ductility ◽  
Strengthening Mechanism ◽  
General Yielding

AbstractIt has been shown that it is possible to obtain significant room temperature tensile ductility in FeAl alloys using iron-rich deviations from stoichiometry. A comparison of the room temperature tensile and compressive behaviors of Fe−50at% Al and Fe−40at% Al shows that FeAl is brittle at higher Al contents because it fractures along grain boundaries before general yielding. Lower aluminium contents reduce the yield stress substantially and hence some ductility is observed before fracture.Addition of boron results in measurable improvements in ductility of Fe−40at% Al and is accompanied by an increase in transgranular tearing on the fracture surface, suggesting a grain boundary strengthening mechanism.Increasing the cooling rate following annealing at 1273 K results in a large increase in the yield strength and a corresponding decrease in ductility.

Behavior of Basal Plane Dislocations and Low Angle Grain Boundary Formation in Hexagonal Silicon Carbide

2007 ◽  
Vol 556-557 ◽  
pp. 231-234 ◽  
Author(s):  
Yi Chen ◽  
Govindhan Dhanaraj ◽  
William M. Vetter ◽  
Rong Hui Ma ◽  
Michael Dudley
Keyword(s):  
Silicon Carbide ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Basal Plane ◽  
Opposite Sign ◽  
Three Dimensional ◽  
Cross Slip ◽  
X Ray ◽  
Tilt Boundaries ◽  
Edge Dislocations

The interactions between basal plane dislocations (BPDs) and threading screw and edge dislocations (TSDs and TEDs) in hexagonal SiC have been studied using synchrotron white beam x-ray topography (SWBXT). TSDs are shown to strongly interact with advancing basal plane dislocations (BPDs) while TEDs do not. A BPD can cut through an individual TED without the formation of jogs or kinks. The BPDs were observed to be pinned by TSDs creating trailing dislocation dipoles. If these dipoles are in screw orientation segments can cross-slip and annihilate also potentially leaving isolated trailing loops. The three-dimensional (3D) distribution of BPDs can lead to aggregation of opposite sign edge segments leading to the creation of low angle grain boundaries (LAGBs) characterized by pure basal plane tilt of magnitude determined by the net difference in densities of the opposite sign dislocations. Similar aggregation can also occur against pre-existing prismatic tilt boundaries made up of TED walls with the net difference in densities of the opposite sign dislocations contributing some basal plane tilt character to the LAGB.

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