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The influence of heat treatment and plastic deformation on the bio‐degradation of a Mg‐Y‐RE alloy
Author(s) -
Gunde Petra,
Furrer Angela,
Hänzi Anja C.,
Schmutz Patrik,
Uggowitzer Peter J.
Publication year - 2010
Publication title -
journal of biomedical materials research part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.849
H-Index - 150
eISSN - 1552-4965
pISSN - 1549-3296
DOI - 10.1002/jbm.a.32350
Subject(s) - materials science , corrosion , oxide , alloy , yttrium , dielectric spectroscopy , degradation (telecommunications) , composite material , polarization (electrochemistry) , microstructure , metallurgy , layer (electronics) , simulated body fluid , electrolyte , electrochemistry , scanning electron microscope , electrode , telecommunications , chemistry , computer science
In this study the bio‐degradation behavior of a Mg‐Y‐RE alloy in different heat treatment states with respect to the alloy's potential application as biodegradable implant material was investigated by electrochemical impedance spectroscopy in two body‐similar fluids. The heat treatments increase the degradation resistance of the alloy and lead to the formation of a thermal oxide layer on the sample surface and to a change in microstructure such as the distribution of yttrium. The varying Y distribution in the alloy does not significantly influence the degradation behavior, and all samples show a similar low polarization resistance. However, samples with a thermal oxide layer, which consists mainly of Y 2 O 3 , degrade much more slowly and feature remarkably high polarization resistance. Nevertheless, in some cases localized corrosion attack occurs and drastically impairs performance. Cracks in the oxide layer, intentionally induced by straining of the samples and which in practice could originate from the implantation process, reduce the corrosion resistance. However, these samples perform still better than polished specimens and show a macroscopically homogeneous degradation behavior without localized corrosion. Microscopically, corrosion attacks start at the cracks and undermining of the oxide layer occurs with time. For all the material conditions a remarkable dependence of the degradation rate on the electrolyte is noted. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010