Growth of Grain Boundary Precipitates as a Function of Misorientation in an Al-5 WT% Cu Alloy

1993 ◽  
Vol 319 ◽  
Author(s):  
M. A. Cantrell ◽  
G. J. Shiflet

AbstractThe size evolution of θ phase (CuAl2) precipitates as a function of time was used to study the growth of grain boundary precipitates in an Al-5 wt % Cu alloy. The kinetics were: modeled using the Brailsford and Aaron treatment of the collector plate mechanism. It was found, for a given time, that the size varied in a reproducible manner as a function of misorientation between the grains. Precipitate size was found to vary from 5 x 10-6 cm to 5 x 10-5 cm, while misorientation varied from 20 to 50 degrees for a given heat treatment period. Grain boundary misorientation was determined to be the most important factor influencing precipitate size for a given grain boundary. The grain boundary plane orientation plays a secondary role in the growth of precipitates. From these data, the relationship between grain boundary misorientation and grain boundary diffusion has been determined.

Author(s):  
D. B. Williams ◽  
A. D. Romig

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).


2005 ◽  
Vol 475-479 ◽  
pp. 305-308 ◽  
Author(s):  
Yoshitaka Adachi ◽  
Fu Xing Yin ◽  
Kazunari Hakata ◽  
Kaneaki Tsuzaki

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.


1993 ◽  
Vol 20 (1-4) ◽  
pp. 231-242 ◽  
Author(s):  
Valerie Randle

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.


Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5715
Author(s):  
Jun Ding ◽  
Sheng-Lai Zhang ◽  
Quan Tong ◽  
Lu-Sheng Wang ◽  
Xia Huang ◽  
...  

The effects of grain boundary misorientation angle (θ) on mechanical properties and the mechanism of plastic deformation of the Ni/Ni3Al interface under tensile loading were investigated using molecular dynamics simulations. The results show that the space lattice arrangement at the interface is dependent on grain boundary misorientations, while the interfacial energy is dependent on the arrangement. The interfacial energy varies in a W pattern as the grain boundary misorientation increases from 0° to 90°. Specifically, the interfacial energy first decreases and then increases in both segments of 0–60° and 60–90°. The yield strength, elastic modulus, and mean flow stress decrease as the interfacial energy increases. The mechanism of plastic deformation varies as the grain boundary misorientation angle (θ) increases from 0° to 90°. When θ = 0°, the microscopic plastic deformation mechanisms of the Ni and Ni3Al layers are both dominated by stacking faults induced by Shockley dislocations. When θ = 30°, 60°, and 80°, the mechanisms of plastic deformation of the Ni and Ni3Al layers are the decomposition of stacking faults into twin grain boundaries caused by extended dislocations and the proliferation of stacking faults, respectively. When θ = 90°, the mechanisms of plastic deformation of both the Ni and Ni3Al layers are dominated by twinning area growth resulting from extended dislocations.


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