scholarly journals Deformation and Fracture Behavior of Tial

1990 ◽  
Vol 186 ◽  
Author(s):  
C. L. Fu ◽  
M. H. Yoo
Keyword(s):  
Flow Stress ◽  
Total Energy ◽  
Elastic Constants ◽  
First Principles ◽  
Fracture Behavior ◽  
Anomalous Temperature Dependence ◽  
Anomalous Temperature ◽  
Deformation And Fracture ◽  
Low Energies ◽  
Elastic Shear

AbstractFirst-principles total-energy calculations of the elastic constants, shear fault energies, and cleavage energies of TiAl are presented. We find a large elastic shear anisotropy along the [011] direction, and high APB energies due to the strong cohesion between Ti and Al layers. Shear faults of SISF, SESF, and twin boundary are predicted to be prevalent due to their low energies. The anomalous temperature dependence of flow stress is explained by the cross-slip pinning and fault dragging mechanisms. The intrinsic brittleness of TiAl is discussed in terms of the low mobility of 1/2[110] dislocations.

Anomalous temperature dependence of flow stress in a Fe3Al alloy

2000 ◽  
Vol 42 (3) ◽  
pp. 271-276 ◽  
Author(s):  
Jin-Hwa Song ◽  
Tae Kwon Ha ◽  
Young Won Chang
Keyword(s):  
Flow Stress ◽  
Temperature Dependence ◽  
Anomalous Temperature Dependence ◽  
Anomalous Temperature ◽  
Fe3al Alloy

scholarly journals Anomalous Temperature Dependence of NQR Frequencies

1990 ◽  
Vol 45 (3-4) ◽  
pp. 449-458
Author(s):  
R. J. C. Brown
Keyword(s):  
Heat Capacity ◽  
Temperature Dependence ◽  
Elastic Constants ◽  
Pressure Dependence ◽  
Anomalous Temperature Dependence ◽  
Anomalous Temperature ◽  
Reorientational Motion ◽  
Successes And Failures

Abstract The anomalous temperature dependence of NQR frequencies which is often observed in crystals in which there is reorientational motion of ions or molecules is considered. Two theories of the phenomena, the jump rotation theory and the pseudo-spin theory, are described, and their successes and failures are discussed. The importance of considering other properties such as pressure dependence of NQR, heat capacity, and elastic constants is emphasized, and it is shown that neither theory is entirely satisfactory at present.

High-Pressure Third-Order Elastic Constants of MgO Single Crystal: First-Principles Investigation

2019 ◽  
Vol 74 (5) ◽  
pp. 447-456
Author(s):  
Jianbing Gu ◽  
Chenju Wang ◽  
Bin Sun ◽  
Weiwei Zhang ◽  
Dandan Liu
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
Total Energy ◽  
Elastic Constants ◽  
First Principles ◽  
Predictive Ability ◽  
Theoretical Method ◽  
Third Order ◽  
Third Order Elastic Constants ◽  
First Time

AbstractHigh-pressure third-order elastic constants of materials have rarely been investigated experimentally and theoretically to date, so the predictive ability of the method of the volume-conserving, homogeneous deformations based on the first-principles total-energy calculations is tested for the first time in this work. Using this approach, the high-pressure third-order elastic constants ${C_{111}}-3{C_{112}}+2{C_{123}}$, ${C_{111}}/2+3{C_{112}}+{C_{123}}$, ${C_{144}}-{C_{155}}$, and C456 of the MgO single crystal are obtained successfully. Meanwhile, the reliability of this method is also verified by comparing the calculated structural properties and high-pressure second-order elastic constants of the MgO single crystal with the available experimental results and other theoretical predications. Results not only indicate the accuracy of our calculations but also reveal the feasibility of the present theoretical method. It is hoped that the present theoretical method and predictions on the high-pressure third-order elastic constants of the MgO single crystal would serve as a valuable guidance or reference for further related investigations.

First-Principles Calculations of the Elastic Properties of the Nickel-Based L12 Intermetallics

1995 ◽  
Vol 408 ◽  
Author(s):  
D. Iotova ◽  
N. Kioussis ◽  
S. P. Lim ◽  
S. Sun ◽  
R. Wu
Keyword(s):  
Electronic Structure ◽  
Total Energy ◽  
Ab Initio ◽  
Elastic Properties ◽  
Elastic Constants ◽  
First Principles ◽  
Anisotropy Factor ◽  
Full Potential ◽  
First Principles Calculations ◽  
Linear Muffin Tin Orbital

AbstractThe elastic constants of the L12-type ordered nickel-based intermetallics Ni3X (X = Mn, Al, Ga, Si, Ge), have been calculated by means of ab initio total-energy electronic structurecalculations based on the full-potential linear-muffin-tin-orbital (FLMTO) method. Theorigins in the electronic structure of the variation of the elastic constants, bulk and shearmoduli are investigated across the series, and the effects of the anisotropy of bonding chargedensity on the shear anisotropy factor and the degree of ductility is discussed.

Tight-Binding Hamiltonians for Carbon and Silicon

1997 ◽  
Vol 491 ◽  
Author(s):  
D. A. Papaconstantopoulos ◽  
M. J. Mehl ◽  
S. C. Erwin ◽  
M. R. Pederson
Keyword(s):  
Band Structure ◽  
Total Energy ◽  
Elastic Constants ◽  
First Principles ◽  
Equations Of State ◽  
Tight Binding ◽  
First Principles Calculations ◽  
Energy Bands ◽  
Tight Binding Method ◽  
Correct Energy

ABSTRACTWe demonstrate that our tight-binding method - which is based on fitting the energy bands and the total energy of first-principles calculations as a function of volume - can be easily extended to accurately describe carbon and silicon. We present equations of state that give the correct energy ordering between structures. We also show that quantities that were not fitted, such as elastic constants and the band structure of C60, can be reliably obtained from our scheme.

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