scholarly journals Energetic driving force for preferential binding of self-interstitial atoms to Fe grain boundaries over vacancies

2011 ◽  
Vol 64 (9) ◽  
pp. 908-911 ◽  
Author(s):  
M.A. Tschopp ◽  
M.F. Horstemeyer ◽  
F. Gao ◽  
X. Sun ◽  
M. Khaleel
Keyword(s):  
Grain Boundaries ◽  
Driving Force ◽  
Interstitial Atoms ◽  
Preferential Binding

The nucleation of cavities at grain boundaries

1987 ◽  
Vol 45 ◽  
pp. 288-291
Author(s):  
P. J. Goodhew
Keyword(s):  
Surface Tension ◽  
Surface Energy ◽  
Grain Boundaries ◽  
Radiation Damage ◽  
Impurity Concentration ◽  
Driving Force ◽  
Nucleation And Growth ◽  
Phase Boundaries ◽  
Cavity Nucleation ◽  
Spherical Bubble

Cavity nucleation and growth at grain and phase boundaries is of concern because it can lead to failure during creep and can lead to embrittlement as a result of radiation damage. Two major types of cavity are usually distinguished: The term bubble is applied to a cavity which contains gas at a pressure which is at least sufficient to support the surface tension (2g/r for a spherical bubble of radius r and surface energy g). The term void is generally applied to any cavity which contains less gas than this, but is not necessarily empty of gas. A void would therefore tend to shrink in the absence of any imposed driving force for growth, whereas a bubble would be stable or would tend to grow. It is widely considered that cavity nucleation always requires the presence of one or more gas atoms. However since it is extremely difficult to prepare experimental materials with a gas impurity concentration lower than their eventual cavity concentration there is little to be gained by debating this point.

Binding energy of self-interstitial atoms to grain boundaries: An experimental approach

2016 ◽  
Vol 183 ◽  
pp. 139-142 ◽  
Author(s):  
E.V. Sadanov ◽  
O.V. Dudka ◽  
V.A. Ksenofontov ◽  
T.I. Mazilova ◽  
I.V. Starchenko ◽  
...  
Keyword(s):  
Binding Energy ◽  
Grain Boundaries ◽  
Experimental Approach ◽  
Interstitial Atoms

Recovery and recrystallization of the deformed, orderable alloy (Co78Fe22)3V

1991 ◽  
Vol 6 (1) ◽  
pp. 57-70 ◽  
Author(s):  
R.W. Cahn ◽  
M. Takeyama ◽  
J.A. Horton ◽  
C.T. Liu
Keyword(s):  
Electron Microscopy ◽  
Critical Temperature ◽  
Grain Boundaries ◽  
Tensile Testing ◽  
Driving Force ◽  
Age Hardening ◽  
Annealing Temperatures ◽  
Domain Boundaries ◽  
Antiphase Domains ◽  
Annealing Method

An alloy of composition (Co78Fe22)3V, which orders to an L12 superlattice below a critical temperature (Tc) of 910 °C, was rolled to 25–50% reduction in the initially ordered condition and annealed at various temperatures above and below Tc and examined by hardness, tensile testing, optical and electron microscopy and dilatometry, in order to study the progress of recovery and recrystallization. Recrystallization was severely retarded on annealing below Tc; close to Tc, recrystallization was ≈ 300 × slower in the ordered than the disordered range. Although recrystallization started promptly, predominantly at grain boundaries, very rapid recovery-softening of the unrecrystallized regions progressively reduced the driving force for recrystallization and slowed it down drastically. However, at 770°and 500 °C, recovery-softening was replaced by some recovery-hardening (i.e., strain-age hardening). Above Tc, recrystallization was complete in a few seconds and a special annealing method was needed to measure such times accurately. Dilatometric measurements showed that most of the order destroyed by rolling was restored long before recrystallization began, but the restoration was never complete unless the alloy was heated up through Tc and then slow cooled. Electron microscopy showed no sign of any antiphase domains in recrystallized grains except for a few isolated domain boundaries on annealing at 770 °C. A model is proposed to rationalize the incidence of recovery-softening or strain-age hardening at different annealing temperatures.

scholarly journals Evaluation of Mechanical Properties of Σ5(210)/[001] Tilt Grain Boundary with Self-Interstitial Atoms by Molecular Dynamics Simulation

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Liang Zhang ◽  
Cheng Lu ◽  
Linqing Pei ◽  
Xing Zhao ◽  
Jie Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Shear Deformation ◽  
Uniaxial Tension ◽  
Dynamics Simulation ◽  
Interstitial Atoms ◽  
Radiation Induced ◽  
Induced Defects

Grain boundary (GB) can serve as an efficient sink for radiation-induced defects, and therefore nanocrystalline materials containing a large fraction of grain boundaries have been shown to have improved radiation resistance compared with their polycrystalline counterparts. However, the mechanical properties of grain boundaries containing radiation-induced defects such as interstitials and vacancies are not well understood. In this study, we carried out molecular dynamics simulations with embedded-atom method (EAM) potential to investigate the interaction of Σ5(210)/[001] symmetric tilt GB in Cu with various amounts of self-interstitial atoms. The mechanical properties of the grain boundary were evaluated using a bicrystal model by applying shear deformation and uniaxial tension. Simulation results showed that GB migration and GB sliding were observed under shear deformation depending on the number of interstitial atoms that segregated on the boundary plane. Under uniaxial tension, the grain boundary became a weak place after absorbing self-interstitial atoms where dislocations and cracks were prone to nucleate.

Driving force for pure step movement at grain boundaries with vacancy supersaturation

1992 ◽  
Vol 26 (12) ◽  
pp. 1799-1802
Author(s):  
A.V. Katsman ◽  
L. Levin ◽  
M.V. Karpovskyi
Keyword(s):  
Grain Boundaries ◽  
Driving Force ◽  
Step Movement

Inhibition of Grain Coarsening in Nanocrystalline Fe-C Alloys by Interaction between Carbon and Grain Boundaries

2014 ◽  
Vol 904 ◽  
pp. 184-188
Author(s):  
Yu Zeng Chen ◽  
A. Herz ◽  
Christine Borchers ◽  
X.H. Shi ◽  
X.Y. Ma ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Ball Milling ◽  
Grain Growth ◽  
Driving Force ◽  
Grain Coarsening ◽  
Iron Powders

Nanocrystalline Fe-1.77at.%C and Fe-3.27at.%C alloys prepared by ball milling iron powders and graphite powders are annealed below 573K where the precipitation of Fe3C does not occur. Upon annealing, a significant grain coarsening is observed in Fe-1.77at.%C alloy, whereas the grain coarsening is inhibited in Fe-3.27at.%C alloy. Within the framework of thermodynamic theories, the inhibition of grain coarsening in nanocrystalline Fe-C alloys is discussed. It is demonstrated that the inhibition of grain coarsening in the nanocrystalline Fe-C alloys can be ascribed to a vanished driving force for grain growth which is caused by the interaction between carbon and the grain boundaries of nanograins.

Magnetically Driven Selective Grain Growth in Locally Deformed Zn Single Crystals

2004 ◽  
Vol 467-470 ◽  
pp. 763-770 ◽  
Author(s):  
P.J. Konijnenberg ◽  
Dmitri A. Molodov ◽  
Günter Gottstein
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Grain Growth ◽  
Driving Force ◽  
Grain Orientation ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Single Temperature ◽  
Individual Grains

In magnetically anisotropic materials a driving force for grain boundary migration can be induced by an external magnetic ¯eld. It is experimentally shown that annealing of locally deformed Zn single crystals in a suitably directed high magnetic ¯eld results in a growth of new individual grains. Velocities of some solitary moving grain boundaries were measured and their absolute mobilities were estimated at a single temperature. Results are discussed in terms of preferential grain orientation and boundary character.

The Surface Morphology of Titanium Nitride / Copper Bilayers Annealed at High Temperatures

1993 ◽  
Vol 318 ◽  
Author(s):  
Antonio C. Berti ◽  
Shyam P. Murarka ◽  
Laura E. Brooke
Keyword(s):  
Grain Boundary ◽  
Surface Morphology ◽  
Titanium Nitride ◽  
Grain Boundaries ◽  
Driving Force ◽  
Annealing Temperature ◽  
Boundary Energy ◽  
Strong Dependence ◽  
Copper Film ◽  
Copper Films

ABSTRACTBilayers of 40 nm titanium nitride and 500 nm copper were sputter deposited on oxidized silicon substrates. The films were annealed for one hour at temperatures from 400° C to 800° C in either vacuum or Ar/H2, ambients. Neither x-ray diffraction or Rutherford backscattering spectrometry indicated any interaction between the titanium nitride and copper films. While no differences in surface morphology were detected at annealing temperatures of less than 500° C, above this temperature a strong dependence on annealing ambient was found. In the vacuum annealed samples, surface grooves formed at the grain boundaries of the copper film. These grooves became progressively larger as the annealing temperature was increased, eventually leading to void formation. Only small grain boundary grooves were present in the Ar/H2, annealed films regardless of annealing temperature. The driving force for the formation of the grooves is believed to be a difference between the grain boundary and surface energies in the copper films. It is speculated that in Ar/H2 anneals this driving force is reduced because hydrogen segregates to the copper grain boundaries and lowers the grain boundary energy.The formation of grooves was found to retard copper grain growth and texturing. Resistivity of the copper film was also found to increase if the void density was sufficiently high.

Faceting and Migration of Low Angle Tilt Grain Boundaries in Pure Aluminum

2007 ◽  
Vol 558-559 ◽  
pp. 903-908
Author(s):  
Dirk M. Kirch ◽  
Bing Bing Zhao ◽  
Dmitri A. Molodov ◽  
Günter Gottstein
Keyword(s):  
Grain Boundaries ◽  
Driving Force ◽  
Rotation Angle ◽  
Boundary Energy ◽  
Pure Aluminum ◽  
Boundary Surface ◽  
Structural Behavior ◽  
Grain Boundary Energy ◽  
And Migration

The kinetic and structural behavior of symmetrical <100> tilt grain boundaries with rotation angles 8.4°, 12.0°, 14.3° and 16.0° were investigated in-situ in a hot stage SEM in the temperature range between 380°C and 640°C. The results revealed that depending on the rotation angle the boundary either remained straight, became faceted or curved under the driving force provided by the boundary surface tension during high temperature annealing. The transition “facetedcurved boundary” was also found to depend on temperature. The observed behavior is attributed to the anisotropy of grain boundary energy with respect to boundary inclination.

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