Variant Selection in Fcc-to-Bcc Precipitation at Grain Boundaries in Ni-43Cr Alloy

Variant selection of bcc-Cr at the grain boundaries in a supersaturated fcc matrix was studied using a Ni-43Cr alloy. The preferentially selected variant was examined as a function of the grain boundary misorientation, the tilt angle between the {111}fcc plane and the grain boundary plane, and the orientation relationships with respect to both of the adjacent matrix grains.

Download Full-text

Statics and Dynamics of Grain Boundaries in Ni3Al

MRS Proceedings ◽

10.1557/proc-133-137 ◽

1988 ◽

Vol 133 ◽

Author(s):

Diana Farkas

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Cluster Variation Method ◽

Boundary Region ◽

Boundary Plane ◽

Variation Method ◽

Boundary Misorientation ◽

Grain Boundary Plane ◽

Alloy Properties ◽

Experimental Findings

ABSTRACTVarious modeling techniques have been used to study the structure of grain boundaries in ordered compounds, particularly Ni3Al. The techniques include computer simulation, group theoretical analysis and the cluster variation method for high temperature effects. A multiplicity of possible grain boundary structures was analyzed for different misorientations and grain boundary plane location. 1The influence of several alloy properties like atomic size differences and deviation from stochiometry on the occurrence of these different structures is analyzed. The implications of these results for grain boundary misorientation distribution, grain boundary plane location and faceting behavior are discussed and compared to experimental findings. The possibility of orderdisorder transitions in the grain boundary region is also discussed.

Download Full-text

Application of Microtexture Measurements in the SEM to Grain Boundary Parameters

Textures and Microstructures ◽

10.1155/tsm.20.231 ◽

1993 ◽

Vol 20 (1-4) ◽

pp. 231-242 ◽

Cited By ~ 6

Author(s):

Valerie Randle

Keyword(s):

Data Collection ◽

Grain Boundary ◽

Electron Back Scatter Diffraction ◽

Boundary Plane ◽

Geometrical Parameters ◽

Interface Plane ◽

Boundary Misorientation ◽

Grain Boundary Plane ◽

Grain Boundary Misorientation ◽

Plane Scheme

This paper discusses how microtexture data, i.e. individual orientations which are measured on a grain and environmentally specific basis, are applied to grain boundary geometrical parameters. Three main areas are addressed: the “interface-plane” scheme for specifying the five degress of freedom of a boundary, comparisons of experimental techniques for data collection, and representation of grain boundary misorientations in Rodrigues-Frank space. Particular attention is paid to electron back-scatter diffraction as a method of probing grain boundary misorientation and the crystallographic orientation of the grain boundary plane.

Download Full-text

Measurement of solute segregation to grain boundaries in the AEM: A review

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100105096 ◽

1988 ◽

Vol 46 ◽

pp. 606-607

Author(s):

D. B. Williams ◽

A. D. Romig

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Boundary Migration ◽

Grain Boundary Migration ◽

Boundary Misorientation ◽

Collector Plate ◽

Segregation Process ◽

Grain Boundary Misorientation ◽

Structure Boundary ◽

Equilibrium Segregation

The segregation of solute or imparity elements to grain boundaries can occur by three well-defined processes. The first is Gibbsian segregation in which an element of minimal matrix solubility confines itself to a monolayer at the grain boundary. Classical examples include Bi in Cu and S or P in Fe. The second process involves the depletion of excess matrix solute by volume diffusion to the boundary. In the boundary, the solute atoms diffuse rapidly to precipitates, causing them to grow by the ‘collector-plate mechanism.’ Such grain boundary diffusion is thought to initiate “Diffusion-Induced Grain Boundary Migration,” (DIGM). This process has been proposed as the origin of eutectoid transformations or discontinuous grain boundary reactions. The third segregation process is non-equilibrium segregation which result in a solute build-up around the boundary because of solute-vacancy interactions.All of these segregation phenomena usually occur on a sub-micron scale and are often affected by the nature of the grain boundary (misorientation, defect structure, boundary plane).

Download Full-text

The effect of the grain boundary plane on transport properties of grain boundaries in YBa2Cu3O6+x

Physica C Superconductivity ◽

10.1016/s0921-4534(02)01973-1 ◽

2003 ◽

Vol 384 (3) ◽

pp. 377-382

Author(s):

Michael B. Field ◽

Dean J. Miller

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Transport Properties ◽

Boundary Plane ◽

Grain Boundary Plane

Download Full-text

Precipitation on grain boundaries in Al-Mg-Si alloys: The role of grain boundary misorientation

Scripta Materialia ◽

10.1016/j.scriptamat.2021.114494 ◽

2022 ◽

pp. 114494

Author(s):

Zhijun Zhang ◽

N.C. Parson ◽

W.J. Poole

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Boundary Misorientation ◽

Grain Boundary Misorientation

Download Full-text

The role of grain boundary plane orientation on intergranular corrosion of symmetric and asymmetric [110] tilt grain boundaries in directionally solidified pure copper

Scripta Materialia ◽

10.1016/j.scriptamat.2004.03.016 ◽

2004 ◽

Vol 50 (12) ◽

pp. 1417-1421 ◽

Cited By ~ 32

Author(s):

H. Miyamoto ◽

K. Ikeuchi ◽

T. Mimaki

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Intergranular Corrosion ◽

Pure Copper ◽

Boundary Plane ◽

Directionally Solidified ◽

Plane Orientation ◽

Grain Boundary Plane

Download Full-text

Variant selection of grain boundary α by special prior β grain boundaries in titanium alloys

Acta Materialia ◽

10.1016/j.actamat.2014.05.003 ◽

2014 ◽

Vol 75 ◽

pp. 156-166 ◽

Cited By ~ 73

Author(s):

R. Shi ◽

V. Dixit ◽

H.L. Fraser ◽

Y. Wang

Keyword(s):

Grain Boundary ◽

Titanium Alloys ◽

Grain Boundaries ◽

Variant Selection ◽

Selection Of

Download Full-text

Characterization of Zinalco Alloy Superplastically Deformed Using Orientation Imaging Microscopy

MRS Proceedings ◽

10.1557/proc-1242-s4-41 ◽

2009 ◽

Vol 1242 ◽

Cited By ~ 1

Author(s):

Ramos A. Mitsuo ◽

Martínez F. Elizabeth ◽

Negrete S. Jesús ◽

Torres-Villaseñor G.

Keyword(s):

Grain Size ◽

Grain Boundary ◽

Grain Boundaries ◽

Superplastic Deformation ◽

Orientation Imaging Microscopy ◽

Grain Boundary Sliding ◽

Boundary Misorientation ◽

Average Grain Size ◽

Grain Boundary Misorientation ◽

Misorientation Angles

ABSTRACTZinalco alloy (Zn-21mass%Al-2mass%Cu) specimens were deformed superplastically with a strain rate (ε) of 1×10-3 s-1 at homologous temperature (TH) of 0.68 (5 ). It was observed neck formation that indicate nonhomegeneus deformation. Grain size and grain boundaries misorientation changes, due superplastic deformation, were characterized by Orientation Imagining Microscopy (OIM) technique. It was studied three regions in deformed specimens and the results were compared with the results for a specimen without deformation. Average grain size of 1 mm was observed in non-deformed specimen and a fraction of 82% for grain boundary misorientation angles with a grain boundaries angles between 15° and 55° was found. For deformed specimen, the fraction of angles between 15° and 55° was decreced to average value of 75% and fractions of low angle (<5°) and high angle (>55°) misorientations were 10% and 15% respectively. The grain size and high fraction of grain boundary misorientation angles between 15° and 55° observed in the alloy without deformation, are favorable for grain rotation and grain boundary sliding (GBS) procces. The changes observed in the fraction of favorable grain boundary angles during superplastic deformation, shown that the superplastic capacity of Zinalco was reduced with the deformation.

Download Full-text

The structure of a near Σ=27 tilt grain boundary in Ge

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121478 ◽

1992 ◽

Vol 50 (1) ◽

pp. 214-215

Author(s):

Stuart McKernan ◽

C. Barry Carter

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Structural Unit ◽

Perfect Crystal ◽

Boundary Plane ◽

Boundary Structure ◽

Structural Units ◽

Grain Boundary Plane ◽

Grain Boundary Structure ◽

Complex Structural

The modeling of tilt grain boundaries in terms of repeating structural units of varying separation is now a well established concept. High-resolution electron microscope (HREM) images of different tilt grain boundaries in many materials display a qualitative similarity of atomic configurations of the grain boundary structure. These boundaries are frequently described in terms of characteristic structural units, which may be separated from each other by regions of ‘perfect’ crystal (as, for example, in low-angle grain boundaries), or may be contiguous, forming ordered arrays of the structural units along the boundary. In general there will be a different arrangement of the structural units or an arrangement of different structural units, according to the precise geometry of the particular grain boundary. The structure of some special grain boundaries has been examined and these are found to exist in several different configurations, depending on the orientation of the grain boundary plane among other parameters. Symmetry-related symmetric tilt grain boundaries and asymmetric tilt grain boundaries with one grain having a prominent, low-index facet, are commonly observed, low-energy configurations. Structural multiplicity of these configurations along the same grain boundary has been observed in some systems. Defects in the perfect ordering of the structural units may be caused by deviations of the grain boundary plane away from the perfect tilt orientation. Deviations of grain boundary structure away from the exact orientation will also produce defects in the repeating structural unit configuration. These deviations may have a regular and well-defined structure, producing a more complex structural unit.

Download Full-text