Journal ArticleDOI
On high creep activation energies for dispersion strengthened metals
R. W. Lund,W. D. Nlx +1 more
TLDR
In this paper, the contribution of the temperature dependent elastic modulus to the apparent activation energy can be very large and the modulus correction is particularly important at high temperatures and for materials with high stress exponents.Abstract:
Creep studies on dispersion strengthened metals have often resulted in inexplicably high creep activation energies and high stress exponents. An analysis is presented which shows that the contribution of the temperature dependent elastic modulus to the apparent activation energy can be very large. Two cases are examined in which the difference between the apparent activation energy and the activation energy of self diffusion is almost entirely accounted for by the contribution of the temperature dependent elastic modulus. The modulus correction is particularly important at high temperatures and for materials with high stress exponents.read more
Citations
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High temperature creep of Ni-20Cr-2ThO2 single crystals
R.W. Lund,William D. Nix +1 more
TL;DR: The high temperature creep properties of single crystals of Ni-20Cr-2ThO 2 have been investigated in the temperature range 650-1300°C in this article, where single crystal tensile specimens were cut from plates having a large elongated grain structure and constant stress vacuum creep tests were conducted at various stresses and temperatures.
Journal ArticleDOI
Creep behavior of discontinuous SiCAl composites
TL;DR: A review of creep data of discontinuous SiCAl composites (whisker and particulate) shows that the creep behavior of these composites exhibits two main characteristics: (a) the stress dependence of the steady state (or minimum) creep rate, as described by the value of the stress exponent, is high and variable; and (b) the temperature dependence, measured by the creep activation energy, is much larger than that for self-diffusion in aluminum.
Journal ArticleDOI
An examination of the constitutive equation for elevated temperature plasticity
TL;DR: The constitutive relation that links the stress-strain rate-grain size-temperature relation (Mukherjee-Bird-Dorn, MBD correlation) was presented in 1968/1969 to describe the elevated temperature crystalline plasticity has held up well during the intervening quarter of a century.
Journal ArticleDOI
Apparent and effective creep parameters in single crystals of a nickel base superalloy—II. Secondary creep
C Carry,J. L. Strudel +1 more
TL;DR: In this article, the authors derived an effective activation energy of about 60 kcal/mole and an effective stress exponent of the order of 1 for nickel base superalloys under various temperature and applied stress conditions.
Journal ArticleDOI
High temperature creep of silicon carbide particulate reinforced aluminum
TL;DR: In this paper, the effect of stress on the creep properties of 30 vol.% silicon carbide particulate reinforced 6061 aluminum (SiC p -6061 Al), produced by powder metallurgy, has been studied in the temperature range of 618-678 K. The experimental data, which extend over seven orders of magnitude of strain rate, show that the creep curve exhibits a very short steady-state stage; that the stress exponent, n, is high (n > 7.4) and increases with decreasing the applied stress; and that the apparent activation energy for creep
References
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Journal ArticleDOI
Mechanical behavior of crystalline solids at elevated temperature
Oleg D. Sherby,Peter M. Burke +1 more
TL;DR: In this paper, the mechanical behavior of crystalline solids at elevated temperatures is discussed, including the creep properties of metals, solid solutions and two phase alloys, and the properties of two-phase alloys.
Journal ArticleDOI
Steady‐State Creep through Dislocation Climb
TL;DR: In this article, a dislocation climb creep model is considered which does not require the production of immobile dislocations, and the creep equation that results from the analysis is creep rate = Aσ3sinh(Bσ1.5/kT)exp(−Q/kTs), where A and B are constants, σ is the stress, Q is the activation energy of creep and kT has its usual meaning.
Journal ArticleDOI
A model for steady state creep based on the motion of jogged screw dislocations
C.R Barrett,William D. Nix +1 more
TL;DR: In this article, a theory of steady state creep is presented which is based on the diffusion controlled motion of jogged screw dislocations, where the chemical forces on the jogs are balanced by the force on the dislocation due to the applied stress.
Journal ArticleDOI
Factors affecting the high temperature strength of polcyrystalline solids
TL;DR: In this article, the authors compared Weertman's theory of creep based on dislocation climb best describes the experimental data for creep of pure metals at high stresses, and the Nabarro-Herring theory based on atomic diffusion appears applicable at low stresses.
Journal ArticleDOI
The role of grain size and shape in strengthening of dispersion hardened nickel alloys
B.A Wilcox,A.H. Clauer +1 more
TL;DR: In this article, the influence of microstructure on room temperature and elevated temperature strength was investigated and it was found that substructure refinement was a much more potent means of strengthening at room temperature than was dispersion hardening.
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