Mn-promoting formation of a long-period stacking-ordered phase in laser-melted Mg alloys to enhance degradation resistance
Mn-promoting formation of a long-period stacking-ordered phase in laser-melted Mg alloys to enhance degradation resistance
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Mn促进激光熔化镁合金中长周期堆叠有序相的形成，以增强抗退化能力
DOI：
10.1002/maco.201911257
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发表时间：
2020
影响因子：
1.8
通讯作者：
Liao Weiwei
中科院分区：
文献类型：
--
作者：
Shuai Cijun;Liu Long;Gao Chengde;Yang Wenjing;Zhao Zhenyu;Tan Ying;Liao Weiwei
镁合金是一种很有前途的生物医用植入材料。然而，它们非常快的降解速率极大地限制了它们的应用。具有长周期堆积有序（LPSO）结构的稀土相有利于提高镁合金的抗劣化性能。事实上，镁合金中LPSO相的形成取决于它们的层错能。层错能越低，形成的LPSO相越多。在本研究中，将锰（Mn）合金化到镁合金ZK 30 - 10 Gd（含3wt%）中Zn和10重量% Gd）通过选择性激光熔化来促进LPSO相的形成。Mn作为合金元素，由于Mn与Mg原子半径的较大差异，导致晶格畸变较大，有利于层错的形成，有利于降低层错能。结果表明，随着锰含量从0增加到1.2wt%，LPSO相的面积分数从12.22%增加到22.37%，（Mg，Zn）3Gd相的面积分数从9.31%减少到2.32%。ZK 30 - 10 Gd-0.6Mn具有最高的耐降解性（重量损失率为0.38 mg · cm-2· day-1）。降解阻力的增强有两个原因。一方面，LPSO相的增多为降解产物的成核提供了更多的位置，有利于降解产物膜的形成，从而保护镁基体。抑制（Mg，Zn）_3Gd相的析出，可降低电偶腐蚀。
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)3Gd 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)3Gd phase precipitation could reduce galvanic corrosion.