Improving the Reliability of EBSD-Based Texture Analysis by a New Large Area Mapping Technique

2011 ◽  
Vol 702-703 ◽  
pp. 566-569
Author(s):  
Kemal Davut ◽  
Stefan Zaefferer
Keyword(s):  
Grain Size ◽  
Mapping Technique ◽  
Small Step ◽  
Large Area ◽  
Step Size ◽  
Average Grain Size ◽  
Very Large Datasets ◽  
Ebsd Technique ◽  
Xrd Techniques ◽  
Statistical Representativeness

The relevance of EBSD-based investigations for statements on the macroscopic or mesoscopic behavior of materials is critically relying on the statistical representativeness of the data. Particularly, the statistical reliability of the EBSD-based results (e.g. texture, phase fraction or grain size) remains an open question since the areas observed by the EBSD technique are quite small compared to XRD techniques. It has already been shown that covering larger areas and probing more grains with the help of large step sizes is beneficial in terms of representativeness [1]. On the other hand, small step sizes are beneficial in terms of grain reconstruction and data clean-up. However, step sizes significantly smaller than the average grain size of the material lead to either covered areas or number of probed grains being too small to be representative or to very large datasets and correspondingly long measurement times. In this contribution, the benefits of a new mapping technique [1] that joins the advantages of large and small step size measurements will be demonstrated. The representativeness of the EBSD datasets obtained by classical and this new mapping techniques were compared by calculating the pole figure symmetries of a TRIP steel. The results show that the proposed mapping technique significantly improves the reliability and representativeness of EBSD-based texture measurements.

Self-Diffusion as A Limiting Factor of a-SiGe Crystallization

1997 ◽  
Vol 469 ◽  
Author(s):  
F. Edelman ◽  
T. Raz ◽  
Y. Komem ◽  
P. Werner ◽  
W. Beyer ◽  
...  
Keyword(s):  
Grain Size ◽  
Nanocrystalline Structure ◽  
Limiting Factor ◽  
In Situ Tem ◽  
Large Area ◽  
Self Diffusion ◽  
Glass Substrates ◽  
Vacancy Generation ◽  
Nonequilibrium Vacancy ◽  
Average Grain Size

ABSTRACTHighly doped (∼1018 to 1021cm−3) polycrystalline Si1-xGex films, crystallized from amorphous (a) state at relative low temperatures, are prospective materials in a variety of applications, such as liquid-crystal displays, solar cells and integrated thermoelectric sensors on large-area glass substrates. Since the nature of the grains in the crystallized film defines properties such as carrier mobility, the nucleation and growth process of the a-SiGe films is of fundamental interest. We have studied the crystallization of undoped and highly doped (B or Ga) amorphous SiGe films. The films were deposited by RFCVD or molecular beam on oxidized (001)Si and for TEM study on cleaved NaCl. The incubation time and grain growth rate were studied by means of in situ TEM using a heating stage. The crystallization process in undoped SiGe followed Avrami relationship. An average grain size between 0.1 and 2μm was observed. However, the highly p-doped (with B or Ga) SiGe films crystallized to a stable nanocrystalline structure (grain size <10nm). The process of the a-SiGe crystallization is explained on the basis of self-diffusion. During the first stage, the nucleation of crystals is accompanied with nonequilibrium vacancy generation at the amorphous/crystalline interface. During the second stage, the growth of crystals takes place by vacancy outdiffusion which is hindered by B and Ga interaction with vacancies.

scholarly journals Grain Size-Related Strengthening and Softening of a Precompressed and Heat-Treated Mg–Zn–Ca Alloy

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 351 ◽  
Author(s):  
Patrik Dobroň ◽  
Daria Drozdenko ◽  
Klaudia Horváth Fekete ◽  
Juraj Olejňák ◽  
Jan Bohlen
Keyword(s):  
Grain Size ◽  
Thermal Treatment ◽  
Electron Backscatter Diffraction ◽  
Deformation Behaviour ◽  
Strengthening Effect ◽  
Average Grain Size ◽  
Ebsd Technique ◽  
Size Interval ◽  
Evolution Of Microstructure ◽  
The Impact

The impact of precompression, thermal treatment and its combination on the deformation behaviour of an extruded Mg–Zn–Ca (ZX10) alloy was studied with respect to a varied average grain size. The Hall–Petch plot was used to highlight the impact in a wide grain size interval. The initial texture of the wrought alloy was characterized by X-ray diffraction. Moreover, the evolution of microstructure and texture was provided by the electron backscatter diffraction (EBSD) technique. The obtained results indicate the strong contribution of deformation-thermal treatment on the resulting deformation behaviour. Particularly, after precompression and heat treatment, higher strengthening effect was observed in the reversed tensile loaded compared to compressed samples without any change in the Hall–Petch slope throughout the grain size interval. Unlike this strengthening effect, a reversed tension–compression yield asymmetry with higher strength values in compression has been obtained.

scholarly journals Microstructure and Texture Evolution of Aluminum in the Al-Nb/Ti/Ni Composite Fabricated by the ARB Process

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Nan Ye ◽  
Xueping Ren
Keyword(s):  
Electron Microscopy ◽  
Grain Size ◽  
Texture Evolution ◽  
Shear Bands ◽  
Rolling Texture ◽  
Shear Texture ◽  
Electron Backscattered Diffraction ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Ebsd Technique

The Al-Nb/Ti/Ni composite was fabricated from pure Al, Ni, Ti, and Nb sheets by the ARB technology. The microstructure evolution was observed by scanning electron microscopy, x-ray diffraction, and transmission electron microscopy. The evolution was evaluated by the electron backscattered diffraction (EBSD) technique. A couple of results we obtained showed that the microstructure of Al changed from equiaxed grains to a lamellar structure, and the grain size in the ND decreased gradually. Finally, the average grain size in the ND was 0.31 μm. Additionally, the fraction of HAGBs increased after the third pass, resulting from the dynamic recovery and the shear bands. The texture evolution was tested by electron backscattered diffraction. After the fourth pass, the Al exhibited a combination texture of rolling texture and shear texture. The rolling texture components were composed of Copper{112}<111>, Dillamore{4 4 11}<11 11 8>, S{123}<634>, and Brass{011}<211>, and the shear texture components were Rotated Cube {001}<110> and {111}//ND. The microhardness of Ni, Ti, Nb, and Al was improved in the ARB process and finally reached 226.4, 246.3, 187.2, and 44.2 HV, respectively.

Laser Crystallized Polysilicon Thin Films and Applications

1995 ◽  
Vol 403 ◽  
Author(s):  
J. B. Boyce ◽  
P. Mei ◽  
D. K. Fork ◽  
G. B. Anderson ◽  
R. I. Johnson
Keyword(s):  
Grain Size ◽  
Amorphous Silicon ◽  
Grain Growth ◽  
Excimer Laser ◽  
Laser Fluence ◽  
Polycrystalline Silicon ◽  
Grain Structure ◽  
Large Area ◽  
Materials Properties ◽  
Average Grain Size

AbstractPulsed excimer-laser crystallization of amorphous silicon on non-crystalline substrates is an important processing technique for large-area polycrystalline silicon films and devices. Interest stems, in large part, from proposals to use polycrystalline silicon on glass in large-area electronic applications, such as flat-panel active matrix displays and two-dimensional imaging systems. The polycrystalline silicon is envisioned to increase the functionality and reduce costs over the current circuits that use amorphous silicon. Also, it is found that laser-crystallized polycrystalline silicon exhibits some interesting materials properties, such as a sharp peak in the average grain size with large lateral grain growth as a function of excimer laser energy density. The average grain size increases with increasing laser fluence and peaks on the order of several microns or two orders of magnitude larger than the film thickness. The grain size then decreases with further increases in laser fluence. This peak in grain size is accompanied by a similar peak in the Hall electron mobility. This is a significant relationship for devices since the grain structure has a substantial influence on electrical properties. But to the detriment of device parameters, this large lateral grain growth occurs over a very arrow range of laser fluences and is accompanied by a corresponding peak in the surface roughness of the films. These relationships between laser processing conditions, materials properties, and device parameters force a compromise between large grain size for high mobility and homogeneity of material for uniformity of device characteristics. A window does exist in process parameter space where good-quality devices with uniform characteristics have been obtained. In addition, these attributes have been achieved under conditions that yield good polycrystalline silicon and good amorphous silicon devices on the same wafer within a mm of one another, allowing for hybrid polycrystalline and amorphous silicon circuits.

(001)-Textured Laser-Crystallized Silicon thin Films on Glass Substrates

2001 ◽  
Vol 685 ◽  
Author(s):  
M. Nerding ◽  
S. Christiansen ◽  
G. Esser ◽  
U. Urmoneit ◽  
A. Otto ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Amorphous Silicon ◽  
Continuous Wave ◽  
Defect Density ◽  
Large Area ◽  
Glass Substrates ◽  
Surface Normal ◽  
Average Grain Size ◽  
Polycrystalline Silicon Films

AbstractWe investigate the microstructure of polycrystalline silicon films (grain size, texture and grain boundary population) on glass substrates. These films are produced from amorphous silicon precursor layers by scanning the raw beam of a continuous wave Ar+- ion laser operated at a wavelength of 514 nm over the amorphous silicon thereby crystallizing it. The materials applicability for devices in large area electronics strongly depends on the orientation of the surface normal, the average grain size and the defect density and population. Transmission electron microscopy together with electron back-scattering diffraction analysis of the crystallized layers reveal grain widths of about 10μm and grain lengths of several 10 μm. Under certain procesing conditions a preferred (001)-surface normal orientation (texture) forms. The grain boundary population is dominated in the textured films by coincidence boundaries, essentially twin boundaries of first and second order as well as Σ=5 boundaries.

Surface Modification and its Influence on the Microstructure and Creep Resistance of Nickel Based Superalloy René 77 / Modyfikacja Powierzchniowa Oraz Jej Wpływ Na Mikrostrukture I Wytrzymałosc Na Pełzanie Odlewów Z Nadstopu Niklu Ren´E 77

2013 ◽  
Vol 58 (1) ◽  
pp. 95-98 ◽  
Author(s):  
M. Zielinska ◽  
J. Sieniawski
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Surface Modification ◽  
Turbine Blades ◽  
Processing Parameters ◽  
Grain Structure ◽  
Creep Tests ◽  
Cobalt Aluminate ◽  
Nickel Based Superalloy ◽  
Average Grain Size

Superalloy René 77 is very wide used for turbine blades, turbine disks of aircraft engines which work up to 1050°C. These elements are generally produced by the investment casting method. Turbine blades produced by conventional precision casting methods have coarse and inhomogeneous grain structure. Such a material often does not fulfil basic requirements, which concern mechanical properties for the stuff used in aeronautical engineering. The incorporation of controlled grain size improved mechanical properties. This control of grain size in the casting operation was accomplished by the control of processing parameters such as casting temperature, mould preheating temperature, and the use of grain nucleates in the face of the mould. For nickel and cobalt based superalloys, it was found that cobalt aluminate (CoAl2O4) has the best nucleating effect. The objective of this work was to determine the influence of the inoculant’s content (cobalt aluminate) in the surface layer of the ceramic mould on the microstructure and mechanical properties at high temperature of nickel based superalloy René 77. For this purpose, the ceramic moulds were made with different concentration of cobalt aluminate in the primary slurry was from 0 to 10% mass. in zirconium flour. Stepped and cylindrical samples were casted for microstructure and mechanical examinations. The average grain size of the matrix ( phase), was determined on the stepped samples. The influence of surface modification on the grain size of up to section thickness was considered. The microstructure investigations with the use of light microscopy and scanning electron microscopy (SEM) enable to examine the influence of the surface modification on the morphology of ’ phase and carbides precipitations. Verification of the influence of CoAl2O4 on the mechanical properties of castings were investigated on the basis of results obtained form creep tests.

scholarly journals ODS EUROFER Steel Strengthened by Y-(Ce, Hf, La, Sc, and Zr) Complex Oxides

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1148 ◽  
Author(s):  
Roman Husák ◽  
Hynek Hadraba ◽  
Zdeněk Chlup ◽  
Milan Heczko ◽  
Tomáš Kruml ◽  
...  
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Complex Oxides ◽  
Oxide Dispersion Strengthened ◽  
Interparticle Spacing ◽  
Oxide Dispersion ◽  
Strengthening Effect ◽  
Dispersion Strengthening ◽  
Doping Element ◽  
Average Grain Size

Oxide dispersion-strengthened (ODS) materials contain homogeneous dispersions of temperature-stable nano-oxides serving as obstacles for dislocations and further pinning of grain boundaries. The strategy for dispersion strengthening based on complex oxides (Y-Hf, -Zr, -Ce, -La) was developed in order to refine oxide dispersion to enhance the dispersion strengthening effect. In this work, the strengthening of EUROFER steel by complex oxides based on Y and elements of the IIIB group (lanthanum, scandium) and IVB group (cerium, hafnium, zirconium) was explored. Interparticle spacing as a dispersoid characteristic appeared to be an important factor in controlling the dispersion strengthening contribution to the yield strength of ODS EUROFER steels. The dispersoid size and average grain size of ODS EUROFER steel were altered in the ranges of 5–13 nm and 0.6–1.7 µm, respectively. Using this strategy, the yield strength of the prepared alloys varied between 550 MPa and 950 MPa depending on the doping element.

Sign in / Sign up

Export Citation Format

Share Document