Abstract
The composite model which has been created by Mughrabi, and developed by several other researchers, is analyzed with respect to high-temperature creep of Al and an Al– Mg alloy. Data for structural parameters such as local and global internal stresses, and dislocation densities have been obtained from X-ray line profile analyses and stress dip tests. Based on the composite model, quantitative relations have been derived which convert the internal stresses gained from X-ray profile analysis into those obtained from stress dip tests. This allowed for a detailed check of the composite model and its formalism describing local and global external and internal stresses, and local and global dislocation densities, during creep at high temperatures. While the local and global internal stresses show an excellent coincidence, the dislocation densities and subboundary volume fractions derived from experiment and modelling show certain deviations; however, these can be related to simplifications of equations used which are not part of the composite model.
The investigation was performed within the frame of a joint Austrian – Czech project granted by the Austrian Institute for East and South Europe. Partial support of the Grant Agency of the Czech Academy of Science within grants A2041202 and A2041203 is gratefully acknowledged. M.Z. and E.S. are grateful to the Austrian Science Fund (FWF) which provided finances under project P 17095 N02.
References
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Appendix
In the following, a procedure is described for the modeling of local stresses which starts from the principles of composite models [7, 8] for high temperature steady state creep.
In steady state, the overall nonelastic strain rate is given by the sum of contributions from motion of free dislocations,
In pure aluminum, the velocity of dislocations in subgrain interiors is expressed by Eq. (6b). The strain rate due to migration of subgrain boundaries can also be described by the Orowan equation
The velocity of subgrain boundary migration is written as
where vm0 is a temperature dependent pre-exponential term.
The calculation starts for given external conditions, i. e. temperature and applied stress (523 K, 20 MPa and 673 K, 2.5 MPa). For a chosen applied stress, the value of local stress σw and of volume fraction fw as derived from X-ray measurements are taken (cf. Table 1). The values of microstructural quantities w, ρc and s are calculated by means of the above Eqs. (8), (24) and (25). Then the ratio of the preexponential terms for the chosen temperature, vm0/vs0, is calculated. For the next applied stress, only the volume fraction from X-ray measurements is taken. From equations (A1) to (A3), the coupling condition
In the modeling of the Al –Mg behaviour, the dislocation velocity in subgrain interiors is governed by a viscous glide mechanism [7]
where B is a temperature dependent constant. The modeling procedure is analogous to that in pure Al. The results are given in Fig. 5. The calculated relative stress in hard regions, σw/σ, decreases with the increasing applied stress in agreement with both data from X-ray measurements and the previous model of Meier et al. [7].
© 2006 Carl Hanser Verlag, München
Artikel in diesem Heft
- Frontmatter
- Professor Dr. Gernot Kostorz 65 years
- Dislocation micromechanisms under single slip conditions
- Characterisation of short-range order using dislocations
- Between microscopic and mesoscopic descriptions of twin–twin interaction
- Influence of the thermoelastic effect on the acoustic properties of pure metals at low temperatures
- Recent progress in the area of bulk metallic glasses
- Formation of the ABC6-type ordered structure in fcc alloys
- Short-range order in Fe-21.9 at.% Al
- Criteria for developing castable, creep-resistant aluminum-based alloys – A review
- Phase decomposition and precipitation of metastable A2 phase in B2 ordered Co–Al–Fe alloys
- Atomic migration and ordering phenomena in bulk and thin films of FePd and FePt
- Late-stage coarsening of oil droplets of excess oil in microemulsions following a temperature quench
- Small-angle scattering from spherical particles on randomly oriented interfaces
- Ripening of L12 Ni3Ti precipitates in the framework of the trans-interface diffusion-controlled theory of particle coarsening
- Texture evolution in equiaxed polycrystalline L10-ordered FePd during coarsening at 600 °C
- Modulated structures in amorphous films of Cr-silicide prepared by electron-beam-deposition
- Early stages of nucleation and growth of Guinier –Preston zones in Al–Zn–Mg and Al–Zn–Mg–Cu alloys
- Experimental and theoretical characterization of Al3Sc precipitates in Al–Mg–Si–Cu–Sc–Zr alloys
- Ag2Al plates in Al–Ag alloys
- A critical analysis of the composite model as applied to high-temperature creep of Al and an Al–Mg alloy
- Damage behaviour of an Al2O3 particle-reinforced 6061 alloy induced by monotonic and cyclic deformation
- Deformation behaviour of ultrafine-grained magnesium with 3 vol.% graphite
- Press/Presse
- Conferences/Konferenzen
- Frontmatter
- Editorial
- Professor Dr. Gernot Kostorz 65 years
- Articles BBasic
- Dislocation micromechanisms under single slip conditions
- Characterisation of short-range order using dislocations
- Between microscopic and mesoscopic descriptions of twin–twin interaction
- Influence of the thermoelastic effect on the acoustic properties of pure metals at low temperatures
- Recent progress in the area of bulk metallic glasses
- Formation of the ABC6-type ordered structure in fcc alloys
- Short-range order in Fe-21.9 at.% Al
- Criteria for developing castable, creep-resistant aluminum-based alloys – A review
- Phase decomposition and precipitation of metastable A2 phase in B2 ordered Co–Al–Fe alloys
- Atomic migration and ordering phenomena in bulk and thin films of FePd and FePt
- Late-stage coarsening of oil droplets of excess oil in microemulsions following a temperature quench
- Small-angle scattering from spherical particles on randomly oriented interfaces
- Ripening of L12 Ni3Ti precipitates in the framework of the trans-interface diffusion-controlled theory of particle coarsening
- Articles AApplied
- Texture evolution in equiaxed polycrystalline L10-ordered FePd during coarsening at 600 °C
- Modulated structures in amorphous films of Cr-silicide prepared by electron-beam-deposition
- Early stages of nucleation and growth of Guinier –Preston zones in Al–Zn–Mg and Al–Zn–Mg–Cu alloys
- Experimental and theoretical characterization of Al3Sc precipitates in Al–Mg–Si–Cu–Sc–Zr alloys
- Ag2Al plates in Al–Ag alloys
- A critical analysis of the composite model as applied to high-temperature creep of Al and an Al–Mg alloy
- Damage behaviour of an Al2O3 particle-reinforced 6061 alloy induced by monotonic and cyclic deformation
- Deformation behaviour of ultrafine-grained magnesium with 3 vol.% graphite
- Notifications/Mitteilungen
- Press/Presse
- Conferences/Konferenzen
Artikel in diesem Heft
- Frontmatter
- Professor Dr. Gernot Kostorz 65 years
- Dislocation micromechanisms under single slip conditions
- Characterisation of short-range order using dislocations
- Between microscopic and mesoscopic descriptions of twin–twin interaction
- Influence of the thermoelastic effect on the acoustic properties of pure metals at low temperatures
- Recent progress in the area of bulk metallic glasses
- Formation of the ABC6-type ordered structure in fcc alloys
- Short-range order in Fe-21.9 at.% Al
- Criteria for developing castable, creep-resistant aluminum-based alloys – A review
- Phase decomposition and precipitation of metastable A2 phase in B2 ordered Co–Al–Fe alloys
- Atomic migration and ordering phenomena in bulk and thin films of FePd and FePt
- Late-stage coarsening of oil droplets of excess oil in microemulsions following a temperature quench
- Small-angle scattering from spherical particles on randomly oriented interfaces
- Ripening of L12 Ni3Ti precipitates in the framework of the trans-interface diffusion-controlled theory of particle coarsening
- Texture evolution in equiaxed polycrystalline L10-ordered FePd during coarsening at 600 °C
- Modulated structures in amorphous films of Cr-silicide prepared by electron-beam-deposition
- Early stages of nucleation and growth of Guinier –Preston zones in Al–Zn–Mg and Al–Zn–Mg–Cu alloys
- Experimental and theoretical characterization of Al3Sc precipitates in Al–Mg–Si–Cu–Sc–Zr alloys
- Ag2Al plates in Al–Ag alloys
- A critical analysis of the composite model as applied to high-temperature creep of Al and an Al–Mg alloy
- Damage behaviour of an Al2O3 particle-reinforced 6061 alloy induced by monotonic and cyclic deformation
- Deformation behaviour of ultrafine-grained magnesium with 3 vol.% graphite
- Press/Presse
- Conferences/Konferenzen
- Frontmatter
- Editorial
- Professor Dr. Gernot Kostorz 65 years
- Articles BBasic
- Dislocation micromechanisms under single slip conditions
- Characterisation of short-range order using dislocations
- Between microscopic and mesoscopic descriptions of twin–twin interaction
- Influence of the thermoelastic effect on the acoustic properties of pure metals at low temperatures
- Recent progress in the area of bulk metallic glasses
- Formation of the ABC6-type ordered structure in fcc alloys
- Short-range order in Fe-21.9 at.% Al
- Criteria for developing castable, creep-resistant aluminum-based alloys – A review
- Phase decomposition and precipitation of metastable A2 phase in B2 ordered Co–Al–Fe alloys
- Atomic migration and ordering phenomena in bulk and thin films of FePd and FePt
- Late-stage coarsening of oil droplets of excess oil in microemulsions following a temperature quench
- Small-angle scattering from spherical particles on randomly oriented interfaces
- Ripening of L12 Ni3Ti precipitates in the framework of the trans-interface diffusion-controlled theory of particle coarsening
- Articles AApplied
- Texture evolution in equiaxed polycrystalline L10-ordered FePd during coarsening at 600 °C
- Modulated structures in amorphous films of Cr-silicide prepared by electron-beam-deposition
- Early stages of nucleation and growth of Guinier –Preston zones in Al–Zn–Mg and Al–Zn–Mg–Cu alloys
- Experimental and theoretical characterization of Al3Sc precipitates in Al–Mg–Si–Cu–Sc–Zr alloys
- Ag2Al plates in Al–Ag alloys
- A critical analysis of the composite model as applied to high-temperature creep of Al and an Al–Mg alloy
- Damage behaviour of an Al2O3 particle-reinforced 6061 alloy induced by monotonic and cyclic deformation
- Deformation behaviour of ultrafine-grained magnesium with 3 vol.% graphite
- Notifications/Mitteilungen
- Press/Presse
- Conferences/Konferenzen