On the Microstructure of HPT Processed Cu under Variation of Deformation Parameters

Schafler, Erhard; Dubravina, Anna; Mingler, Bernhard; Karnthaler, H. P.; Zehetbauer, M.

doi:10.4028/www.scientific.net/msf.503-504.51

Cited by 23 publications

(15 citation statements)

References 14 publications

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“…Obviously, the same parallelity of strain dependences of T max and external stress was found, as demonstrated by Figure 8 for a pressure of 4 GPa (similar correlations have also been found for 2 and 8 GPa). Even more direct evidence for the strain-dependent change of longrange internal stresses comes from previous X-ray profile analyses, which are shown in Figure 9: [29] The higher is the shear strain accumulated, the higher is the level of internal stresses in parallel to that of the external ones. From a critical shear strain reached, the microstructure starts to recover after HPT.…”

Section: Strain Dependence Of Q Due To Assistance Of Long-range Intermentioning

confidence: 97%

Activation Enthalpies of Deformation-Induced Lattice Defects in Severe Plastic Deformation Nanometals Measured by Differential Scanning Calorimetry

Setman

Kerber

Schafler

et al. 2009

Metall Mater Trans A

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Samples of 99.99 pct pure copper and nickel of 99.998 pct purity were deformed by highpressure torsion (HPT) at different hydrostatic pressures, to different shear strains. Activation enthalpies (Q) were determined by differential scanning calorimetry (DSC) using Kissinger's method. For the one annealing peak found in HPT Cu, Q amounts to Q = 0.78 to 0.48 eV depending on the shear strain applied. In the case of Ni, the activation enthalpies of the two annealing peaks were determined as Q = 0.65 eV and Q = 0.95 eV, respectively, with no obvious dependence on shear strain, although this has been indicated by the annealing peak temperatures. Applying defect specific analyses of the annealing peaks, it turned out that the larger Q value represents the annihilation of dislocations and agglomerates, while the smaller one reflects the annihilation of single or double vacancies. Concerning the strain dependence of the larger Q, two possible explanations have been discussed: (1) the annihilation of dislocations assisted by the strain-dependent density of vacancy agglomerates and (2) the annihilation of dislocations enhanced by a strain-dependent level of long-range internal stresses. Because of closer correlations of Q with external and internal stresses at very high shear strains, explanation (2) has been favored.

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Section: Strain Dependence Of Q Due To Assistance Of Long-range Intermentioning

confidence: 97%

Activation Enthalpies of Deformation-Induced Lattice Defects in Severe Plastic Deformation Nanometals Measured by Differential Scanning Calorimetry

Setman

Kerber

Schafler

et al. 2009

Metall Mater Trans A

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“…It was found that the dislocation density increases with increasing numbers of ECAP passes and saturates after 4-8 passes for both pure fcc metals and solid solutions [45,[65][66][67][68][69][70][71]. As an example, the dislocation density versus the imposed strain for an Al-3% Mg specimen is plotted in Fig.…”

Section: Evolution Of Microstructure During Ecapmentioning

confidence: 99%

Characteristics of face-centered cubic metals processed by equal-channel angular pressing

2007

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This review surveys the characteristics of face-centered cubic (fcc) metals and alloys processed by equal-channel angular pressing (ECAP). The significance of the Hall-Petch relationship for ultrafine grained structures is examined and the dependence of the saturated stress obtained in ECAP on the absolute melting temperature is described and discussed. In addition, the flow processes at low temperatures in ultrafine-grained materials and the microstructural evolution of the dislocation densities and precipitates in some alloys of practical importance are also considered briefly.

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“…The size and size-distribution of crystallites, grains, or subgrains, and the dislocation structure were studied intensively in different metals and alloys, e.g. Al [69], Al-alloys [69][70][71], Cu [72][73][74][75][76][77][78], or Ni [79][80][81], processed by SPD procedures at room temperature, e.g. by equal channel angular pressing (ECAP) or high pressure torsion (HPT).…”

Section: 5mentioning

confidence: 99%

Nanocrystalline materials studied by powder diffraction line profile analysis

Ungár¹,

Gubicza²

2007

Zeitschrift Für Kristallographie - Crystalline Materials

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Abstract. X-ray powder diffraction is a powerful tool for characterising the microstructure of crystalline materials in terms of size and strain. It is widely applied for nanocrystalline materials, especially since other methods, in particular electron microscopy is, on the one hand tedious and time consuming, on the other hand, due to the often metastable states of nanomaterials it might change their microstructures. It is attempted to overview the applications of microstructure characterization by powder diffraction on nanocrystalline metals, alloys, ceramics and carbon base materials. Whenever opportunity is given, the data provided by the X-ray method are compared and discussed together with results of electron microscopy. Since the topic is vast we do not try to cover the entire field.

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On the Microstructure of HPT Processed Cu under Variation of Deformation Parameters

Cited by 23 publications

References 14 publications

Activation Enthalpies of Deformation-Induced Lattice Defects in Severe Plastic Deformation Nanometals Measured by Differential Scanning Calorimetry

Activation Enthalpies of Deformation-Induced Lattice Defects in Severe Plastic Deformation Nanometals Measured by Differential Scanning Calorimetry

Characteristics of face-centered cubic metals processed by equal-channel angular pressing

Nanocrystalline materials studied by powder diffraction line profile analysis

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