HIGH TEMPERATURE INTERNAL FRICTION AND DISLOCATION MOTION IN POLY AND SINGLE CRYSTALS OF F.C.C. METALS

1981 ◽  
Vol 42 (C5) ◽  
pp. C5-439-C5-444 ◽  
Author(s):  
A. Rivière ◽  
J. P. Amirault ◽  
J. Woirgard
Keyword(s):  
High Temperature ◽  
Internal Friction ◽  
Single Crystals ◽  
Dislocation Motion

High Temperature Creep Behavior of Single Crystal Gammpraime and Gamm Laloys

1988 ◽  
Vol 133 ◽  
Author(s):  
M. V. Nathal ◽  
J. O. Diaz ◽  
R. V. Miner
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Single Crystals ◽  
Creep Behavior ◽  
Dislocation Motion ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
High Temperature Creep ◽  
Two Phase ◽  
Temperature Creep

ABSTRACTThe creep behavior of single crystals of γ′ and γ alloys were investigated and compared to the response of two phase superalloys tested previously. High temperature deformation in the γ alloys was characteristic of a climb controlled mechanism, whereas the γ′ based materials exhibited glide controlled creep behavior. The superalloys were much more creep resistant than their constituent phases, which indicates the importance of the γ-γ′ interface as a barrier for dislocation motion during creep.

High‐Temperature Kilocycle Internal Friction in Al2O3 Single Crystals

1961 ◽  
Vol 32 (12) ◽  
pp. 2573-2579 ◽  
Author(s):  
R. J. Huber ◽  
G. S. Baker ◽  
P. Gibbs
Keyword(s):  
High Temperature ◽  
Internal Friction ◽  
Single Crystals

Internal Friction in Plastically Deformed High-Purity NiAl Single Crystals

1998 ◽  
Vol 552 ◽  
Author(s):  
M. Hirscher ◽  
D. Schaible
Keyword(s):  
Internal Friction ◽  
Single Crystals ◽  
High Purity ◽  
Formation Enthalpy ◽  
Dislocation Motion ◽  
Zone Melting ◽  
Interstitial Impurity ◽  
Impurity Atoms ◽  
Kink Pair ◽  
Friction Measurements

ABSTRACTHigh-purity stoichiometric NiAl single crystals have been prepared by crucible-free inductive zone melting and afterwards well annealed at temperatures below 1200 K. Internal friction measurements of torsionally deformed single crystals show two relaxation maxima at 500 and 800 K which anneal during the measurement. The first maximum can be assigned to the dislocation motion by kinkpair formation and the annealing to pinning of these dislocations by interstitial impurity atoms. The second maximum is attributed to the Snoek-Köster relaxation of dislocations in the presence of mobile interstitial impurity atoms and the annealing to the pinning of dislocations by vacancies. The kink-pair formation enthalpy in NiAl was estimated.

High-Temperature Internal Friction Peak in Al–0.008 wt% Sn Single Crystals

1990 ◽  
Vol 121 (2) ◽  
pp. 475-481 ◽  
Author(s):  
G. Y. Tian ◽  
J. Z. Lu ◽  
S. P. Wu ◽  
L. D. Zhang
Keyword(s):  
High Temperature ◽  
Internal Friction ◽  
Single Crystals ◽  
Internal Friction Peak

High-Temperature Mechanical Relaxations in Metals and Metallic Alloys

2006 ◽  
Vol 115 ◽  
pp. 87-98
Author(s):  
Andre Rivière
Keyword(s):  
High Temperature ◽  
Internal Friction ◽  
Single Crystals ◽  
Strain Amplitude ◽  
Cold Work ◽  
Metallic Alloys ◽  
Continuous Heating ◽  
Dislocation Network ◽  
Relaxation Phenomena ◽  
Mechanical Spectroscopy

In spite of numerous works, the relaxation phenomena observed at high temperature (between room temperature and the melting temperature TM) are still under discussion. Because relaxation peaks were observed in single crystals, it is generally considered that the basis of the relaxation mechanism is linked to the dislocation network. The main difficulty for high temperature damping measurements is the great sensitivity of internal friction with several experimental parameters: the heating/cooling rate, maximal applied strain amplitude, sample purity, thermomechanical history of the sample, microstructure, etc. This sensitivity can explain the large scatter in experimental results published by various authors. Moreover, internal friction (IF) measurements performed during continuous heating or cooling and using an apparatus working at a quasi-static frequency, do not allow to completely describe the relaxation phenomena. On the contrary, isothermal mechanical spectroscopy (measurements of internal friction in a large frequency, temperature and maximal strain amplitude ranges) improves the experiments or evidences new relaxation effects. This is illustrated in this paper for various examples: slightly cold worked single crystals, polycrystals after a large cold work and recrystallization, non thermally activated peaks observed in metallic alloys, and relaxation peaks at very high temperature (above 0.9 TM).

scholarly journals Inelastic Behaviour of Ice Ih Single Crystals in the Low-Frequency Range Due to Dislocations

1978 ◽  
Vol 21 (85) ◽  
pp. 375-384 ◽  
Author(s):  
René Vassoille ◽  
Christian Maï ◽  
Joseph Perez
Keyword(s):  
High Temperature ◽  
Internal Friction ◽  
Single Crystals ◽  
Empirical Relation ◽  
Low Frequency ◽  
Frequency Range ◽  
High Temperature Range ◽  
Temperature Range ◽  
Inelastic Behaviour ◽  
Torsional Pendulum

Abstract The inelastic behaviour of ice Ih single crystals has been investigated by an inverted torsional pendulum in the low-frequency range. Three features are distinguished: (i) a relaxation peak previously observed by several authors in the higher-frequency range, (ii) an internal friction increasing with temperature in the high-temperature range (230–273 K), (iii) within this high-temperature range, internal friction becomes amplitude dependent, and this dependence becomes greater the greater the temperature. In this case, the internal friction has been interpreted in terms of movements of dislocations. Hence, the experimental results are interpreted with a model of internal friction based on an empirical relation for the velocity of dislocations. This model of internal friction is in fair agreement with experimental data . It is possible then to get an estimate of dislocation density. Hence it is shown that internal friction experiments can be useful in the study of the plastic behaviour of ice single crystals.

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