Compressive creep of dense Bi2Sr1.7CaCu2Ox

1992 ◽  
Vol 7 (9) ◽  
pp. 2360-2364 ◽  
Author(s):  
J.L. Routbort ◽  
K.C. Goretta ◽  
D.J. Miller ◽  
D.B. Kazelas ◽  
C. Clauss ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Activation Energy ◽  
Transmission Electron Microscopy ◽  
Steady State ◽  
Steady State Creep ◽  
Steady State Creep Rate ◽  
Lower Stress ◽  
Dislocation Glide ◽  
Transmission Electron ◽  
Partial Pressures

Dense polycrystalline Bi2Sr1.7CaCu2Ox (2212) was deformed from 780–835 °C in oxygen partial pressures, Po2, of 103 to 2 × 104 Pa. Results could be divided into two stress regimes: one at lower stress in which the steady-state creep rate, ∊, was proportional to stress, γ, having an activation energy of 990 ± 190 kJ/mole and being independent of PO2, and another at higher stress in which ∊ was proportional to σn, with n ≍ 5–6. Transmission electron microscopy supported the interpretation that in the lower-stress viscous regime, creep was controlled by diffusion, whereas dislocation glide and microcracking were responsible for strain accommodation at higher stresses.

Plastic deformation in icosahedral Al–Pd–Mn alloys

1994 ◽  
Vol 9 (2) ◽  
pp. 343-347 ◽  
Author(s):  
J.E. Shield ◽  
M.J. Kramer ◽  
R.W. McCallum
Keyword(s):  
Electron Microscopy ◽  
Activation Energy ◽  
Transmission Electron Microscopy ◽  
Stress Exponent ◽  
Microstructural Analysis ◽  
High Temperature Creep ◽  
Deformation Characteristics ◽  
Cast Sample ◽  
Dislocation Glide ◽  
Transmission Electron

The deformation characteristics of icosahedral Al70Pd21.5Mn8.5 have been investigated by high temperature creep experiments, and the resultant microstructures have been examined by transmission electron microscopy (TEM). From 730 to 780 °C, microstructural analysis revealed that the deformation is controlled by dislocation glide, with an activation energy of 210 ± 30 kJ/mole and a stress exponent of 1.2 ± 0.2. From 780 to 810 °C, microstructures were characteristic of deformation controlled by dislocation glide and climb. The activation energy and stress exponent were determined to be 1700 ± 80 kJ/mole and 2.9 ± 0.3, respectively. Hardness measurements also reflected an increase in dislocation density, as the hardness of the deformed samples was approximately 10% higher than the as-cast sample.

Plastic deformation in an Al–Cu–Fe icosahedral alloy

1993 ◽  
Vol 8 (6) ◽  
pp. 1199-1202 ◽  
Author(s):  
J.E. Shield ◽  
M.J. Kramer ◽  
R.W. McCallum
Keyword(s):  
Electron Microscopy ◽  
Activation Energy ◽  
Transmission Electron Microscopy ◽  
Plastic Deformation ◽  
Steady State ◽  
Quasi Steady State ◽  
High Temperature Creep ◽  
Steady State Regime ◽  
Transmission Electron ◽  
State Regime

Al—Cu—Fe quasicrystalline alloys have been deformed by high-temperature creep between 680 and 740 °C. Deformations greater than 30% were achieved without cracking. Analysis of the data in the quasi-steady state regime reveals power law behavior with a stress exponent of 2.5. The activation energy for deformation was determined to be 640 ± 20 kJ/mole in the temperature region investigated. Transmission electron microscopy revealed lamellar defects which appear similar to twins.

Compressive creep of YBa2Cu3Ox

1990 ◽  
Vol 5 (12) ◽  
pp. 2766-2770 ◽  
Author(s):  
K. C. Goretta ◽  
J. L. Routbort ◽  
A. C. Biondo ◽  
Y. Gao ◽  
A. R. de Arellano-López ◽  
...  
Keyword(s):  
Activation Energy ◽  
Grain Size ◽  
Steady State ◽  
Creep Rate ◽  
Steady State Creep ◽  
Steady State Creep Rate ◽  
Partial Pressures ◽  
Average Grain Size ◽  
Diffusional Flow ◽  
State Stress

YBa2Cu3Ox was deformed from 850 to 980 °C in oxygen partial pressures of 103 to 105 Pa. Steady-state creep rate, ̇, for P(O2) from 104 to 105 Pa could be expressed as ̇ = Aσ1.0 (GS)−2.8±0.6 exp −(970 ± 130 kJ/mole)/RT, where A is a constant, σ the steady-state stress, GS the average grain size, and R and T have their usual meanings, For P(O2) from 103 to 3 ⊠ 103 Pa, the activation energy decreased to about 650 kJ/mole and for a given temperature creep kinetics were much faster. The data and microscopic observations indicated that creep occurred by diffusional flow. Comparisons with diffusion data for YBa2Cu3Ox suggested that Y or Ba may be rate-controlling diffusing species.

CoSi2 Precipitate Coarsening During Formation of Buried Epitaxial Cosi2 Layers By Ion Beam Synthesis

1990 ◽  
Vol 201 ◽  
Author(s):  
R. Jebasinski ◽  
S. Mantl ◽  
K. Radermacher ◽  
P. Fichtner ◽  
W. Jăger ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Activation Energy ◽  
Transmission Electron Microscopy ◽  
Cross Section ◽  
Microstructural Evolution ◽  
Annealing Temperature ◽  
Ion Beam ◽  
Precipitate Coarsening ◽  
Annealing Temperatures ◽  
Transmission Electron

AbstractThe coarsening of CoSi2 precipitates and the microstructural evolution of (111) Si implanted with 200 keV Co+ ions at 350°C and fluences of 1×1016cm−2 and 6×1016cm−2 were investigated as a function of depth, annealing temperature and annealing time using Rutherford Backscattering Spectroscopy (RBS) and Transmission Electron Microscopy (TEM). After annealing cross-section TEM micrographs show a layered array of platelet-shaped precipitates with preferred facets on {111} planes. The fraction of Co-atoms, that were redistributed during the different annealing temperatures and times, has been used to determine an activation energy for the precipitate coarsening. By applying the Meechan-Brinkman and the change-of-slope methods, we obtained activation energies in the range of 3.2 – 3.6 eV.

Evaluation of the Interface Structure During Stranski-Krastanov Growth of GE(SI) on Si (001)

1991 ◽  
Vol 238 ◽  
Author(s):  
M. Albrecht ◽  
H. P. Strunk ◽  
P. O. Hansson ◽  
E. Bauser
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Liquid Phase ◽  
Liquid Phase Epitaxy ◽  
Interface Structure ◽  
Misfit Dislocations ◽  
Heteroepitaxial Growth ◽  
Dislocation Glide ◽  
Transmission Electron ◽  
Half Loop

ABSTRACTThe initial stages of heteroepitaxial growth of Ge0.85 Si0.15 on Si(001) grown from Bi solution (liquid phase epitaxy) are studid by transmission electron microscopy. Stranski-Krastanov growth is observed to take place. After growth of a pseudomorphic Ge0.85 Si0.15 layer of 4 monolayer thickness, islands form and grow pseudomorphically up to a thickness of 30 nm. Then first misfit dislocations form. The formation process of these dislocations is analyzed and discussed in terms of half loop nucleation at the surface and dislocation glide. Evidence for glide on (110) planes is put forward.

Effect of Off-Stoichiometry on the Creep Behavior of Binary and Ternary Ni3Al

1990 ◽  
Vol 213 ◽  
Author(s):  
Tohru Hayashi ◽  
Tetsumori Shinoda ◽  
Yoshinao Mishima ◽  
Tomoo Suzuki
Keyword(s):  
Activation Energy ◽  
Steady State ◽  
Power Law ◽  
Creep Behavior ◽  
Creep Resistance ◽  
Steady State Creep ◽  
Steady State Creep Rate ◽  
Creep Equation ◽  
Ternary Element ◽  
Ternary Additions

ABSTRACTCompressive creep behavior is investigated In polycrystalline Ni3Al intermetallic compounds in which the focus is put on the effect of offstoichiometry and ternary additions of Ti, Ta, V and Co on the creep resistance of the compounds. In all cases, the steady-state creep rate has the power-law type dependence on the applied stress. The stress exponent thereby obtained leads us to regard the creep behavior of the compound to be of the Class I type. It is shown that the creep resistance Increases with increasing Ni concentration on both sides of the stoichiometric Ni3Al composition and a discontinuity exists in the variation at stoichiometry. The gap at the discontinuity becomes clearer by the addition of ternary element in most cases as compared to the binary Ni3Al. Although the exact reason for the phenomenon is not clearly understood at present, it is shown that it could be interpreted by the concentration dependence of activation energy in the power-law type creep equation.

In-situ transmission electron microscopy of partial-dislocation glide in 4H-SiC under electron radiation

2012 ◽  
Vol 101 (4) ◽  
pp. 042102 ◽  
Author(s):  
Yutaka Ohno ◽  
Ichiro Yonenaga ◽  
Kotaro Miyao ◽  
Koji Maeda ◽  
Hidekazu Tsuchida
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Partial Dislocation ◽  
Electron Radiation ◽  
Dislocation Glide ◽  
Transmission Electron
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