Journal ArticleDOI
Creep strengthening in a discontinuous SiC-Al composite
TLDR
In this article, the authors compared the creep behavior of 30 vol pct SiC-6061 Al and that of its matrix alloy, 6061 Al, and found that the creep rates of the composite are more than one order of magnitude slower than those of the alloy, and the activation energy for creep in the composite is higher than that in the alloy.Abstract:
High-temperature strengthening mechanisms in discontinuous metal matrix composites were examined by performing a close comparison between the creep behavior of 30 vol pct SiC-6061 Al and that of its matrix alloy, 6061 Al. Both materials were prepared by powder metallurgy techniques. The experimental data show that the creep behavior of the composite is similar to that of the alloy in regard to the high apparent stress exponent and its variation with the applied stress and the strong temperature dependence of creep rate. By contrast, the data reveal that there are two main differences in creep behavior between the composite and the alloy: the creep rates of the composite are more than one order of magnitude slower than those of the alloy, and the activation energy for creep in the composite is higher than that in the alloy. Analysis of the experimental data indicates that these similarities and differences in creep behavior can be explained in terms of two independent strengthening processes that are related to (a) the existence of a temperature-dependent threshold stress for creep, τ0, in both materials and (b) the occurrence of temperature dependent load transfer from the creeping matrix (6061 Al) to the reinforcement (SiC). This finding is illustrated by two results. First, the high apparent activation energies for creep in the composite are corrected to a value near the true activation energy for creep in the unreinforced alloy (160 kJ/mole) by considering the temperature dependence of the shear modulus, the threshold stress, and the load transfer. Second, the normalized creep data of the composite fall very close to those of the alloy when the contribution of load transfer to composite strengthening is incorporated in a creep power law in which the applied stress is replaced by the effective stress, the stress exponent,n, equals 5, and the true activation energy for creep in the composite,Q
c
, is equal to that in the alloy.read more
Citations
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Book
Deformation of Earth Materials: An Introduction to the Rheology of Solid Earth
TL;DR: In this article, a comprehensive, unified treatment of the materials science of deformation as applied to solid Earth geophysics and geology is presented in a systematic way covering elastic, anelastic and viscous deformation.
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Rheology of synthetic anorthite‐diopside aggregates: Implications for ductile shear zones
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TL;DR: In this paper, the authors investigated the high-temperature creep strength of fine-grained anorthite-diopside rocks at temperatures ranging from 1323 K to 1523 K and at 300 MPa confining pressure in a Paterson-type gas-medium deformation apparatus.
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Microstructural characteristics and thermal stability of ultrafine grained 6061 Al alloy fabricated by accumulative roll bonding process
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High-temperature mechanical properties of AlSi10Mg specimens fabricated by additive manufacturing using selective laser melting technologies (AM-SLM)
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Journal ArticleDOI
Characterization of a powder metallurgy SiC/Cu–Al composite
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References
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Journal ArticleDOI
Dislocation generation due to differences between the coefficients of thermal expansion
R.J. Arsenault,N. Shi +1 more
TL;DR: In this paper, a simple model based on prismatic punching was developed to account for the relative dislocation density due to the differential thermal contraction, and an in situ transmission electron microscopy investigation was undertaken of dislocation generation at the inclusions due to thermal contraction.
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V.C. Nardone,K.M. Prewo +1 more
TL;DR: In this article, a modified shear lag theory was used to rationalize why the proportional limit of the composite is similar to that of the matrix and why the strength of the SiCw/6061Al is anisotropic.
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
Particle reinforcement of ductile matrices against plastic flow and creep
TL;DR: In this paper, the role of non-deforming particles in reinforcing ductile matrix materials against plastic flow and creep is investigated within the framework of continuum plasticity theory using cell models to implement most of the calculations.
Journal ArticleDOI
The transition from dislocation climb to viscous glide in creep of solid solution alloys
TL;DR: In this article, it was shown that the deformation criterion for viscous glide is given by Bσ 2 k 2 (1 − v γ Gb 3 > T 2 e 2 cb 6 where B ∼ 8 × 1012, σ is the applied stress, k is Boltzmann's constant, v is Poisson's ratio, γ is the stacking fault energy, G is the shear modulus, b is the Burgers vector, T is the absolute temperature, e is the solute-solvent size difference, and c is the concentration