scholarly journals The Effects of Severe Plastic Deformation and/or Thermal Treatment on the Mechanical Properties of Biodegradable Mg-Alloys

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1064 ◽  
Author(s):  
Andrea Ojdanic ◽  
Jelena Horky ◽  
Bernhard Mingler ◽  
Mattia Fanetti ◽  
Sandra Gardonio ◽  
...  
Keyword(s):  
Thermomechanical Processing ◽  
High Pressure Torsion ◽  
Profile Analysis ◽  
Tensile Tests ◽  
Line Profile Analysis ◽  
Thermal Treatments ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Quantitative Evaluations ◽  
Vacancy Concentrations

In this study, five MgZnCa alloys with low alloy content and high biocorrosion resistance were investigated during thermomechanical processing. As documented by microhardness and tensile tests, high pressure torsion (HPT)-processing and subsequent heat treatments led to strength increases of up to 250%; as much as about 1/3 of this increase was due to the heat treatment. Microstructural analyses by electron microscopy revealed a significant density of precipitates, but estimates of the Orowan strength exhibited values much smaller than the strength increases observed. Calculations using Kirchner’s model of vacancy hardening, however, showed that vacancy concentrations of 10−⁵ could have accounted for the extensive hardening observed, at least when they formed vacancy agglomerates with sizes around 50–100 nm. While such an effect has been suggested for a selected Mg-alloy already in a previous paper of the authors, in this study the effect was substantiated by combined quantitative evaluations from differential scanning calorimetry and X-ray line profile analysis. Those exhibited vacancy concentrations of up to about 10−3 with a marked percentage being part of vacancy agglomerates, which has been confirmed by evaluations of defect specific activation migration enthalpies. The variations of Young’s modulus during HPT-processing and during the subsequent thermal treatments were small. Additionally, the corrosion rate did not markedly change compared to that of the homogenized state.

Equal channel angular pressing processing routes and associated structure modification: a differential scanning calorimetry and X-ray line profile analysis

2012 ◽  
Vol 27 (3) ◽  
pp. 194-199 ◽  
Author(s):  
A. Sarkar ◽  
Satyam Suwas ◽  
D. Goran ◽  
J.-J. Fundenberger ◽  
L.S. Toth ◽  
...  
Keyword(s):  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Equal Channel Angular Pressing ◽  
Line Profile ◽  
Profile Analysis ◽  
Line Profile Analysis ◽  
Stored Energy ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Angular Pressing

The effectiveness of different routes of equal channel angular pressing (A, Bc, and C) is studied for commercially pure copper. The stored energy and the activation energy of recrystallization for the deformed samples were quantified using differential scanning calorimetry and X-ray diffraction line profile analysis. Results of the study revealed that the dislocation density and the stored energy are higher in the case of route Bc deformed sample. The activation energy for recrystallization is lower for route Bc.

Nanocrystallization and Dissolution of Immiscible Powder Alloys Using High Pressure Torsion

2010 ◽  
Vol 667-669 ◽  
pp. 151-156
Author(s):  
Susi Kahofer ◽  
Michael Zehetbauer ◽  
Herbert Danninger ◽  
Erhard Schafler ◽  
Michael Kerber ◽  
...  
Keyword(s):  
Room Temperature ◽  
Vickers Microhardness ◽  
High Pressure Torsion ◽  
Profile Analysis ◽  
Line Profile Analysis ◽  
X Ray ◽  
Grain Sizes ◽  
Powder Alloys ◽  
Microhardness Data ◽  
Different Strains

Precompacts out of immiscible systems CuCr (75/25 wt%) and WCu (80/20 wt%), respectively, were made by pressing mixed powders and sintering. By applying different strains and hydrostatic pressures of HPT at room temperature, disc-shaped samples with a diameter of 8 mm were produced. They were investigated by Light Microscopy, Scanning-Electron Microscopy using Back-Scattered Electrons, and X-ray Line Profile Analysis. In addition, Vickers microhardness data were collected. Both systems showed the highest microhardness at a shear strain of about γ = 170. The density (for the case of Cu25Cr) of the consolidated material could be increased to the theoretical value. Microhardness and grain sizes were studied individually for each of the phases, too.

scholarly journals In-Situ Synchrotron Profile Analysis after High-Pressure Torsion Deformation

Crystals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 232 ◽  
Author(s):  
Michael Kerber ◽  
Florian Spieckermann ◽  
Roman Schuster ◽  
Bertalan Joni ◽  
Norbert Schell ◽  
...  
Keyword(s):  
High Pressure ◽  
Hydrostatic Pressure ◽  
High Pressure Torsion ◽  
Profile Analysis ◽  
Heating Process ◽  
Line Profile Analysis ◽  
X Ray ◽  
Pressure Release ◽  
Induced Defects

The presence of hydrostatic pressure is a general crucial characteristic of severe plastic deformation methods for reaching high strains and for introducing large quantities of lattice defects, which are necessary to establish new grain boundaries. Insights into the processes occurring during deformation and the influence of hydrostatic pressure are necessary to help better understand the SPD methods. A special experimental procedure was designed to simulate the hydrostatic pressure release: High pressure torsion (HPT)-deformed microstructure changes related to the release of hydrostatic pressure after the HPT deformation of copper and nickel were studied by freezing the sample before releasing the pressure. High-resolution in-situ X-ray diffraction of the heating process was performed using synchrotron radiation in order to apply X-ray line profile analysis to analyze the pressure release. The results on copper and nickel generally indicated the influence of hydrostatic pressure on the mobility and interaction of deformation-induced defects as well as the resulting microstructure.

Subgrain Size-Distributions, Dislocation Structures, Stacking- and Twin Faults and Vacancy Concentrations in SPD Materials Determined by X-Ray Line Profile Analysis

2006 ◽  
Vol 503-504 ◽  
pp. 133-140 ◽  
Author(s):  
Tamás Ungár
Keyword(s):  
Plastic Deformation ◽  
Line Profile ◽  
Profile Analysis ◽  
Subgrain Size ◽  
Stacking Faults ◽  
Line Profile Analysis ◽  
Size Distributions ◽  
X Ray ◽  
The Status ◽  
Vacancy Concentrations

The fundamentals of X-ray line profile analysis are summarised in terms of subgrain size and size-distribution, dislocation density and dislocation types, especially edge and screw dislocations, intrinsic and extrinsic stacking faults and twin boundaries and vacancies produced during plastic deformation. It is shown that deformation induced vacancy concentrations in the grain boundaries of compressed copper polycrystals are close to the equilibrium values at the melting temperature. The discrepancy between X-ray and TEM size values is discussed in terms subgrain- and grain size. It is shown that this apparent discrepancy might be used to determine the status of fragmentation by severe plastic deformation.

Microstructure of post-deformed ECAP-Ti investigated by Multiple X-Ray Line Profile Analysis

2006 ◽  
Vol 2006 (suppl_23_2006) ◽  
pp. 129-134 ◽  
Author(s):  
E. Schafler ◽  
K. Nyilas ◽  
S. Bernstorff ◽  
L. Zeipper ◽  
M. Zehetbauer ◽  
...  
Keyword(s):  
Line Profile ◽  
Profile Analysis ◽  
Line Profile Analysis ◽  
X Ray

An Assessment of Bulk and Local Stored Energy Measurements in Ultrafine Grained Interstitial Free Steel

2010 ◽  
Vol 89-91 ◽  
pp. 244-249 ◽  
Author(s):  
Sujoy S. Hazra ◽  
Azdiar A. Gazder ◽  
Elena V. Pereloma
Keyword(s):  
Profile Analysis ◽  
Energy Estimates ◽  
Internal Stresses ◽  
Line Profile Analysis ◽  
Interstitial Free ◽  
Stored Energy ◽  
Scanning Calorimetry ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Interstitial Free Steel

The evolution of stored energy and associated thermal behaviour was investigated for an ultrafine grained Ti-IF steel severely deformed by Equal Channel Angular Pressing (ECAP) followed by cold rolling at ambient and liquid nitrogen temperatures. Bulk stored energy measurements by Differential Scanning Calorimetry (DSC) returned 350-600 whereas local stored energy estimates from microhardness, Electron Back-Scattering Diffraction (EBSD) and X-ray line profile analysis resulted in 5-140 . Higher bulk stored energy values correspond to the enthalpy release from all sources of strain in the material volume as well as Ti precipitation during annealing while the lower local stored energy range alludes only to dislocation content or internal stresses. An apparent activation energy of 500-550 suggests sluggish recrystallisation due to excess of Ti in solid solution.

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