TY - JOUR

T1 - Influence of the amount of intermetallics on the degradation of Mg-Nd alloys under physiological conditions

AU - Zhang, Yaping

AU - Huang, Yuanding

AU - Feyerabend, Frank

AU - Blawert, Carsten

AU - Gan, Weimin

AU - Maawad, Emad

AU - You, Sihang

AU - Gavras, Sarkis

AU - Scharnagl, Nico

AU - Bode, Julia

AU - Vogt, Carla

AU - Zander, Daniela

AU - Willumeit-Römer, Regine

AU - Kainer, Karl Ulrich

AU - Hort, Norbert

N1 - We acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Parts of this research were carried out at PETRA III and we would like to thank Dr. Norbert Schell for assistance in using the HEMS beamline. Mr. Gert Wiese in MagIC is also gratefully acknowledged for the technical support. The author Yaping Zhang would like to thank the China Scholarship Council for the award of a fellowship and funding (No. 201604910708 ). Publisher Copyright: © 2020 The Authors. Published by Elsevier Ltd on behalf of Acta Materialia Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

PY - 2021/2/1

Y1 - 2021/2/1

N2 - The influence of amount of intermetallics on the degradation of as-extruded Mg-Nd alloys with different contents of Nd was investigated via immersion testing in DMEM+10% FBS under cell culture conditions and subsequent microstructural characterizations. It is found that the presence of intermetallic particles Mg41Nd5 affects the corrosion of Mg-Nd alloys in two conflicting ways. One is their negative role that their existence enhances the micro-galvanic corrosion. Another is their positive role. Their existence favours the formation of a continuous and compact corrosion layer. At the early stage of immersion, their negative role predominated. The degradation rate of Mg-Nd alloys monotonously increases with increasing the amount of intermetallics. Mg-5Nd alloy with maximum amount of intermetallics suffered from the most severe corrosion. With the immersion proceeding (≥7 days), then the positive role of these intermetallic particles Mg41Nd5 could not be neglected. Owing to the interaction between their positive and negative roles, at the later stage of immersion the corrosion rate of Mg-Nd alloys first increases with increasing the content of Nd, then reaches to the maximum at 2 wt. % Nd. With a further increase of Nd content, a decrease in corrosion rate occurs. The main corrosion products on the surfaces of Mg-Nd alloys include carbonates, calcium-phosphate, neodymium oxide and/or neodymium hydroxide. They are amorphous at the early stage of immersion. With the immersion proceeding, they are transformed to crystalline. The existence of undegradable Mg41Nd5 particles in the corrosion layer can enhance the crystallization of such amorphous corrosion products.

AB - The influence of amount of intermetallics on the degradation of as-extruded Mg-Nd alloys with different contents of Nd was investigated via immersion testing in DMEM+10% FBS under cell culture conditions and subsequent microstructural characterizations. It is found that the presence of intermetallic particles Mg41Nd5 affects the corrosion of Mg-Nd alloys in two conflicting ways. One is their negative role that their existence enhances the micro-galvanic corrosion. Another is their positive role. Their existence favours the formation of a continuous and compact corrosion layer. At the early stage of immersion, their negative role predominated. The degradation rate of Mg-Nd alloys monotonously increases with increasing the amount of intermetallics. Mg-5Nd alloy with maximum amount of intermetallics suffered from the most severe corrosion. With the immersion proceeding (≥7 days), then the positive role of these intermetallic particles Mg41Nd5 could not be neglected. Owing to the interaction between their positive and negative roles, at the later stage of immersion the corrosion rate of Mg-Nd alloys first increases with increasing the content of Nd, then reaches to the maximum at 2 wt. % Nd. With a further increase of Nd content, a decrease in corrosion rate occurs. The main corrosion products on the surfaces of Mg-Nd alloys include carbonates, calcium-phosphate, neodymium oxide and/or neodymium hydroxide. They are amorphous at the early stage of immersion. With the immersion proceeding, they are transformed to crystalline. The existence of undegradable Mg41Nd5 particles in the corrosion layer can enhance the crystallization of such amorphous corrosion products.

KW - Degradation

KW - Intermetallic particles

KW - Magnesium-neodymium alloys

KW - Microstructure

KW - Engineering

UR - http://www.scopus.com/inward/record.url?scp=85097754659&partnerID=8YFLogxK

U2 - 10.1016/j.actbio.2020.11.050

DO - 10.1016/j.actbio.2020.11.050

M3 - Journal articles

C2 - 33279710

AN - SCOPUS:85097754659

VL - 121

SP - 695

EP - 712

JO - Acta Biomaterialia

JF - Acta Biomaterialia

SN - 1742-7061

ER -