First-Principles Calculations of Stacking Faults and Grain Boundaries in Metals

1990 ◽  
Vol 213 ◽  
Author(s):  
K. Hampel ◽  
D.D. Vvedensky ◽  
S. Crampin
Keyword(s):  
Magnetic Properties ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
First Principles ◽  
Stacking Faults ◽  
First Principles Calculations ◽  
Comprehensive Description ◽  
Planar Defects ◽  
Detailed Understanding ◽  
Defect Energies

ABSTRACTA detailed understanding of planar defects plays an important role in the search for a comprehensive description of the mechanical behaviour of metals and alloys. We present calculations for isolated stacking faults and grain boundaries using the layer Korringa-Kohn-Rostoker method including an assessment of the force theorem, which has already proven itself in evaluating defect energies for elemental close-packed metals. These ab initio total energy calculations will be supplemented by a study of the changes in bonding and local magnetic properties near a symmetric Σ5 (310) grain boundary in Fe

Properties of Iron Atoms at Grain Boundaries in Fe and Fe72Al28

1998 ◽  
Vol 527 ◽  
Author(s):  
O. Schneeweiss ◽  
I. Turek ◽  
J. Čermák ◽  
P. Lejček
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Single Crystals ◽  
First Principles ◽  
Magnetic Moments ◽  
Emission Mössbauer Spectroscopy ◽  
First Principles Calculations ◽  
Hyperfine Parameters ◽  
Impurity Atoms ◽  
Atomic Spacing

ABSTRACTLocation of diffused 57Co atoms in single crystals, bicrystals and polycrystals of pure iron and Fe72Al28alloy were investigated by means of emission Mössbauer spectroscopy. To interpret the results, first principles calculations of iron atom magnetic moments and hyper-fine field were carried out. From comparison of M6ssbauer spectra of single crystals with those of bicrystals and polycrystals, an information about grain boundary positions occupied by diffusing atoms is obtained. It is shown that about 5% of the diffusing atoms at the {112} grain boundary of iron are located at the positions either having impurity atoms in the nearest neighbourhood or characterized by larger atomic spacing in comparison with the bulk. In the Fe72Al28 a dominating portion of diffusing atoms have different surrounding than in grain volume. An enrichment of grain boundaries by aluminum could explain their hyperfine parameters.

scholarly journals The Electronic Structure of Grain Boundaries in NB

1990 ◽  
Vol 209 ◽  
Author(s):  
Erik C. Sowa ◽  
A. Gonis ◽  
X. -G. Zhang
Keyword(s):  
Electronic Structure ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Multiple Scattering ◽  
First Principles ◽  
Scattering Theory ◽  
Real Space ◽  
First Principles Calculations ◽  
Densities Of States ◽  
Local Densities

ABSTRACTWe present first-principles calculations of the electronic structure of Nb grain boundaries. These are the first such calculations for a bcc metal using the real-space multiple-scattering theory (RSMST). Local densities of states near a Σ5 twist grain boundary are compared to those for bulk Nb.

The formation of H bubbles at small-angle tilt grain boundaries in W films

2016 ◽  
Vol 18 (48) ◽  
pp. 33103-33108 ◽  
Author(s):  
Zhihai He ◽  
H. Y. He ◽  
R. Ding ◽  
B. C. Pan ◽  
J. L. Chen
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Small Angle ◽  
First Principles ◽  
First Principles Calculations ◽  
Tilt Grain Boundary

The accumulation of H at the small-angle tilt grain boundary (GB) in the W(001) surface is investigated, on the basis of the first-principles calculations.

First-Principles Studies on Grain Boundary Energies of [110] Tilt Grain Boundaries in Aluminum

2007 ◽  
Vol 561-565 ◽  
pp. 1837-1840 ◽  
Author(s):  
Y. Inoue ◽  
Tokuteru Uesugi ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Atomic Structure ◽  
First Principles ◽  
Boundary Structure ◽  
First Principles Calculations ◽  
Atomic Structures ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Tilt Grain Boundary

The grain boundary structure and its energy are necessary for the fundamental understanding of the physical properties of materials. In aluminum, three distinct atomic structures of a Σ9(221)[110] tilt grain boundary have been reported in previous studies using atomistic simulations and a high-resolution transmission electron microscopy (HRTEM). In this work, we studied the atomic structure and energy of the Σ9 tilt grain boundary in aluminum using first-principles calculations. A comparison of the grain boundary energies among the three distinct Σ9 tilt grain boundaries determined through first-principles calculations allowed us to identify the most stable atomic structure of Σ9 tilt grain boundary in aluminum.

First-principles calculations of the local magnetic properties of face-centred cubic disordered Fe-Pd alloys

1993 ◽  
Vol 5 (30) ◽  
pp. 5343-5352 ◽  
Author(s):  
Cai-Jian Wang ◽  
Luo He-Lie ◽  
Zeng Zhi ◽  
Zheng-Qing-Qi
Keyword(s):  
Magnetic Properties ◽  
First Principles ◽  
First Principles Calculations

scholarly journals First Principles Calculations of Defects in Unstable Crystals: Austenitic Iron

2011 ◽  
Vol 1363 ◽  
Author(s):  
G.J. Ackland ◽  
T.P.C. Klaver ◽  
D.J. Hepburn
Keyword(s):  
Point Defects ◽  
First Principles ◽  
Defect Formation ◽  
Single Layer ◽  
Temperature Limit ◽  
Reference State ◽  
First Principles Calculations ◽  
General Picture ◽  
Bcc Iron ◽  
Defect Energies

ABSTRACTFirst principles calculations have given a new insight into the energies of point defects in many different materials, information which cannot be readily obtained from experiment. Most such calculations are done at zero Kelvin, with the assumption that finite temperature effects on defect energies and barriers are small. In some materials, however, the stable crystal structure of interest is mechanically unstable at 0K. In such cases, alternate approaches are needed. Here we present results of first principles calculations of austenitic iron using the VASP code. We determine an appropriate reference state for collinear magnetism to be the antiferromagnetic (001) double-layer (AFM-d) which is both stable and lower in energy than other possible models for the low temperature limit of paramagnetic fcc iron. Another plausible reference state is the antiferromagnetic (001) single layer (AFM-1). We then consider the energetics of dissolving typical alloying impurities (Ni, Cr) in the materials, and their interaction with point defects typical of the irradiated environment. We show that the calculated defect formation energies have fairly high dependence on the reference state chosen: in some cases this is due to instability of the reference state, a problem which does not seem to apply to AFM-d and AFM-1. Furthermore, there is a correlation between local free volume magnetism and energetics. Despite this, a general picture emerge that point defects in austenitic iron have geometries similar to those in simpler, non-magnetic, thermodynamically stable FCC metals. The defect energies are similar to those in BCC iron. The effect of substitutional Ni and Cr on defect properties is weak, rarely more than tenths of eV, so it is unlikely that small amounts of Ni and Cr will have a significant effect on the radiation damage in austenitic iron at high temperatures.

First principles calculations of optical and magnetic properties of SrFe 2 O 4 compound under pressure

2014 ◽  
Vol 378 (35) ◽  
pp. 2644-2650 ◽  
Author(s):  
Zohre Javdani ◽  
Hojat Allah Badehian ◽  
Hamdollah Salehi ◽  
Peiman Amiri
Keyword(s):  
Magnetic Properties ◽  
First Principles ◽  
First Principles Calculations ◽  
Optical And Magnetic Properties
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