Titel
The Effects of Severe Plastic Deformation and/or Thermal Treatment on the Mechanical Properties of Biodegradable Mg-Alloys
Autor*in
Jelena Horky
Center for Health & Bioresources, Biomedical Systems, AIT Austrian Institute of Technology GmbH
Bernhard Mingler
Center for Health & Bioresources, Biomedical Systems, AIT Austrian Institute of Technology GmbH
... show all
Abstract
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.
Stichwort
Mg alloysevere plastic deformation (SPD)intermetallic precipitatesvacancy agglomeratescorrosion
Objekt-Typ
Sprache
Englisch [eng]
Persistent identifier
Erschienen in
Titel
Metals
Band
10
Ausgabe
8
ISSN
2075-4701
Erscheinungsdatum
2020
Publication
MDPI AG
Projekt
Kod / Identifikator
I2815-N36
Fördergeber
Erscheinungsdatum
2020
Zugänglichkeit
Rechte
Rechteangabe
© 2020 by the authors
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