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Mn‐promoting formation of a long‐period stacking‐ordered phase in laser‐melted Mg alloys to enhance degradation resistance
Author(s) -
Shuai Cijun,
Liu Long,
Gao Chengde,
Yang Wenjing,
Zhao Zhenyu,
Tan Ying,
Liao Weiwei
Publication year - 2020
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.201911257
Subject(s) - materials science , degradation (telecommunications) , stacking fault energy , nucleation , stacking , stacking fault , phase (matter) , alloy , magnesium , metallurgy , chemical engineering , composite material , chemistry , organic chemistry , dislocation , engineering , telecommunications , computer science
Magnesium (Mg) alloys are promising candidates for use as biomedical implant materials. However, their very fast degradation rate greatly restricts their application. A rare earth phase possessed with a long‐period stacking‐ordered (LPSO) structure was in favor of enhancing the degradation resistance of Mg alloys. In fact, the formation of the LPSO phase in Mg alloys depends on their stacking fault energy. The lower the stacking fault energy, the more the LPSO phase formed. In this study, manganese (Mn) was alloyed to Mg alloy ZK30–10Gd (containing 3 wt.% Zn and 10 wt.% Gd) via selective laser melting to promote the formation of the LPSO phase. As an alloying element, Mn could be in favor of reducing stacking fault energy due to the fact that the large difference between the atomic radius of Mn and that of Mg induced large lattice distortion to facilitate forming stacking faults. The results showed that as the Mn content increased from 0 to 1.2 wt.%, the area fraction of LPSO phase increased from 12.22% to 22.37%, meanwhile the area fraction of (Mg,Zn) 3 Gd phase decreased from 9.31% to 2.32%. The ZK30–10Gd–0.6Mn possessed the highest degradation resistance (weight loss rate 0.38 mg · cm −2 · day −1 ). The enhancement of degradation resistance had two reasons. On the one hand, more LPSO phase provided more sites for nucleation of degradation products, which could promote the formation of a homogeneous and compact degradation product film to protect the Mg matrix. On the other hand, the inhibition of (Mg,Zn) 3 Gd phase precipitation could reduce galvanic corrosion.