A Grain Boundary Engineering Approach to Promote Special Boundaries in a Pb-base Alloy

2002 ◽  
Vol 730 ◽  
Author(s):  
D.S. Lee ◽  
H.S. Ryoo ◽  
S.K. Hwang
Keyword(s):  
Grain Boundary ◽  
Thermomechanical Processing ◽  
Base Alloy ◽  
Coincidence Site Lattice ◽  
Grain Boundary Engineering ◽  
Site Lattice ◽  
Special Boundaries ◽  
Engineering Approach ◽  
Electrochemical Evaluation ◽  
Battery Application

AbstractA grain boundary engineering approach was employed to improve the microstructure of a commercial Pb-base alloy for better performance in automobile battery application. Through a combination of cold working, recrystallization and subsequent thermomechanical-processing, it was possible to increase the fraction of the low ∑ coincidence site lattice boundaries up to 91% in addition to the substantial grain refinement. A preliminary electrochemical evaluation indicated a better corrosion resistance in the experimental material laden with the special boundaries. The high frequency of the coincidence site lattice boundaries in the specimens was interpreted in terms of the '∑3 regeneration' model proposed in previous works.

Grain Boundary Engineering of ECAPed OFHC Copper

2016 ◽  
Vol 879 ◽  
pp. 2192-2197
Author(s):  
Wen Feng ◽  
Jun Hui Zhang ◽  
Sen Yang
Keyword(s):  
Grain Boundary ◽  
Equal Channel Angular Pressing ◽  
Coincidence Site Lattice ◽  
Electron Back Scatter Diffraction ◽  
Ofhc Copper ◽  
Grain Boundary Engineering ◽  
Site Lattice ◽  
Angular Pressing ◽  
Grain Boundary Character ◽  
High Fraction

Grain boundary character distributions (GBCD) of OFHC copper equal-channel angular pressing (ECAP) deformed and then annealed were analyzed by electron back scatter diffraction (EBSD). The experimental results showed that a combination of ECAP deformation and annealing treatments could significantly increase the fraction of low-Σ coincidence site lattice (CSL) boundaries (Σ≤29) and effectively interrupt the connectivity of random boundaries network in OFHC copper. An increase of low-Σ CSL boundaries from 45.27 to 71.06% was observed in as-received material after one pass ECAP strain followed by annealing at 350 °C for 48 h. The connectivity of random boundaries network was interrupted by high fraction of low-Σ CSL boundaries.

Micromechanisms Involved in Grain Boundary Engineering

2005 ◽  
Vol 495-497 ◽  
pp. 1225-1230
Author(s):  
Andre Luiz Pinto ◽  
Carlos Sergio da Costa Viana ◽  
Luiz Henrique de Almeida
Keyword(s):  
Grain Boundary ◽  
Electron Backscatter Diffraction ◽  
Boundary Migration ◽  
Coincidence Site Lattice ◽  
Inconel 625 ◽  
Grain Boundary Engineering ◽  
Inconel 600 ◽  
Special Boundaries ◽  
Deformation Step ◽  
Backscatter Diffraction

Grain boundary engineering has been applied to different materials in order to increase properties particularly sensitive to intergranular phenomena. This work analyses the micromechanisms that allow the control of the amount of special boundaries which respect coincidence site lattice theory. α-brass, a lead alloy, Inconel 625 and Inconel 600 were submitted to different thermomechanical treatments and were analyzed via electron backscatter diffraction in order to characterize their grain boundaries. The occurrence of thin twins in some crystal directions during the deformation step seems to determine the results obtained as well as strain induced boundary migration.

Grain Boundary Engineering: Progress and Challenges

2007 ◽  
Vol 539-543 ◽  
pp. 3389-3394 ◽  
Author(s):  
Wei Guo Wang
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Electron Backscatter Diffraction ◽  
Coincidence Site Lattice ◽  
Grain Boundary Character Distribution ◽  
Grain Boundary Engineering ◽  
Special Boundaries ◽  
Grain Boundary Character ◽  
Proposed Model ◽  
Backscatter Diffraction

The progress of grain boundary engineering (GBE) is overviewed and the challenges for further investigations emphasized. It points out that, the electron backscatter diffraction (EBSD) reconstruction of grain boundaries, which gives the information of connectivity interruption of general high angle boundaries (HABs), is more significant than purely pursuing high frequency of so-called special boundaries. The criterion for the optimization of grain boundary character distribution (GBCD) needs to be established. The energy spectrum and the degradation susceptibility of grain boundaries of various characters including HABs and low Σ（Σ≤29） coincidence site lattice (CSL) needs to be studied and ascertained. And finally, the newly proposed model of non-coherent Σ3 interactions for GBCD optimization are discussed.

Clustering of coincident site lattice boundaries in polycrystals

1988 ◽  
Vol 46 ◽  
pp. 630-631
Author(s):  
Valerie fendle ◽  
Brian Ralph
Keyword(s):  
Electron Microscope ◽  
Grain Boundary ◽  
Thermomechanical Processing ◽  
Austenitic Stainless Steels ◽  
Coincident Site Lattice ◽  
Thin Foil ◽  
Texture Measurement ◽  
Bulk Specimen ◽  
Site Lattice ◽  
Special Boundaries

The distribution of coincident site lattice (CSL) and other geometrically special boundaries have been analysed in the form of “grain misorientation texture” (GMT) plots for several systems (pure nickel, a number of austenitic stainless steels and a complex superalloy, 1-5). Several heat treatment conditions have been investigated for each system. Principally, electron back scattering (EBS) in a scanning electron microscope has been used to collect the “microtexture” (i.e. grain specific) data which combines the considerable advantages of bulk specimen texture analysis, grain environment specification with semi-automatic operation. These data are currently being supplemented with thin foil transmission electron microscope (TEM) analyses which permit more detailed investigation of the grain boundary parameters (especially grain boundary planes).Conventional texture measurement shave akey role in assessing the overall changes which occur during thermomechanical processing. However, the very detailed orientation measurements give only a statistical picture and this means that neither the geometry of individual boundaries (the GMT) nor ary tendency for clustering of particular texture types or boundary types may be detected.

Evolution of Microstructure in Pure Nickel during Processing for Grain Boundary Engineering

2013 ◽  
Vol 753 ◽  
pp. 97-100 ◽  
Author(s):  
Brian Lin ◽  
Gregory S. Rohrer ◽  
Anthony D. Rollett ◽  
Yuan Jin ◽  
Nathalie Bozzolo ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Thermomechanical Processing ◽  
Electron Backscatter Diffraction ◽  
Experimental Studies ◽  
Recrystallization Process ◽  
Grain Boundary Engineering ◽  
Triple Junctions ◽  
Special Boundaries ◽  
Before And After ◽  
Over Time

Grain boundary engineered (GBE) materials have improved properties that are associated with the high fraction special Σ3n boundaries in the microstructure, where n = 1,2,3. Previous experimental studies with high purity nickel before and after thermomechanical processing have shown that the fraction of Σ3 boundaries increased by at least factor of two [1]. Electron backscatter diffraction (EBSD) is used to characterize the evolution of these special boundaries throughout the recrystallization process of a 25% cold rolled sample annealed at 490°C. The fractions of the Σ3 boundaries and coherent twins have been measured over time revealing a steadily increasing behavior over the entire microstructure. However partitioning to only include recrystallized regions reveals a different behavior in the Σ3 boundaries as fractions, which increase rapidly at first and then stagnate over time. Additional triple junction characterization was performed to monitor the evolution of triple junctions containing special boundaries.

Fracture Strengths of Individual Grain Boundaries in Ni3Ai Using a Miniaturized Disk Bend Test

1991 ◽  
Vol 238 ◽  
Author(s):  
Douglas E. Meyers ◽  
Alan J. Ardell
Keyword(s):  
Plastic Deformation ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Coincident Site Lattice ◽  
Bend Test ◽  
High Angle ◽  
Load Drop ◽  
Site Lattice ◽  
Special Boundaries

ABSTRACTThe results of our initial efforts at measuring the fracture strengths of grain boundaries In Ni3Al using a miniaturized disk-bend test are presented. The samples tested were 3 mm in diameter and between 150 and 300 μm thick. An Ingot of directlonally-solidlfled, boron-free Ni3Al containing 24% Al was annealed between 1300 and 1350 °C to induce grain growth, producing many grain boundaries In excess of 1.5 mm in length. Specimens were cut from these In such a way that one long grain boundary was located near a diameter of the specimen. The relative orientations of the grains on either side of the boundary were determined from electron channeling patterns. Low-angle boundaries are so strong they do not fracture; Instead the samples deform In a completely ductile manner. High-angle boundaries always fracture, but only after considerable plastic deformation of the two grains flanking them. Fracture is Indicated by a load drop in the load vs. displacement curves. A method involving extrapolation of the elastic portion of these curves to the displacement at fracture is used to estimate the fracture stresses. This procedure yields consistent values of the fracture strengths of high-angle boundaries. The measured stresses are large (∼2 to 3 GPa), but considerably smaller than those required for the fracture of special boundaries, as predicted by computer simulations. No correlation was found between the fracture stresses or loads and the geometry of the high-angle boundaries, many of which are close to, but deviate from, coincident site lattice orientations.

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