Magnesium-based nanocomposites:A review from mechanical,creep and fatigue properties

The addition of nanoscale additions to magnesium(Mg)based alloys can boost mechanical characteristics without noticeably decreasing ductility.Since Mg is the lightest structural material,the Mg-based nanocomposites(NCs)with improved mechanical properties are appealing materials for lightweight structural applications.In contrast to conventional Mg-based composites,the incorporation of nano-sized reinforcing particles noticeably boosts the strength of Mg-based nanocomposites without significantly reducing the formability.The present article reviews Mg-based metal matrix nanocomposites(MMNCs)with metallic and ceramic additions,fabricated via both solid-based(sintering and powder metallurgy)and liquid-based(disintegrated melt deposition)technologies.It also reviews strengthening models and mechanisms that have been proposed to explain the improved mechanical characteristics of Mg-based alloys and nanocomposites.Further,synergistic strengthening mecha-nisms in Mg matrix nanocomposites and the dominant equations for quantitatively predicting mechanical properties are provided.Furthermore,this study offers an overview of the creep and fatigue behavior of Mg-based alloys and nanocomposites using both traditional(uniaxial)and depth-sensing indentation techniques.The potential applications of magnesium-based alloys and nanocomposites are also surveyed.

掺锌羟基磷灰石-沸石/聚己内酯复合材料作为镁基体涂层提高其体外腐蚀和抗菌性能

开发掺锌羟基磷灰石-沸石(Zn HA-Zeo)和聚己内酯(PCL)复合涂层,以提高镁基体的耐腐蚀性能和抗菌性能。采用浸涂技术在室温下将Zn HA-Zeo/PCL涂覆在镁基体上,对样品进行场发射扫描电子显微镜(FESEM)、X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、能量色散X射线光谱(EDX)和抗菌电位测试。结果表明,复合涂层由羟基磷灰石(HA)、磷钙锌石(scholzite)、沸石和PCL相组成。EDX谱显示钙(Ca)、硅(Si)、铝(Al)、锌(Zn)、磷(P)和氧(O)元素的存在。复合涂层表面的显微形貌为球形,厚度为226~260μm。掺锌HA-Zeo复合涂层具有较高的耐蚀性,对镁基体表面提供足够的保护,使其不被电流腐蚀。与未掺杂的涂层相比,掺锌HA-Zeo涂层对大肠杆菌具有更好的抗菌活性。综合结果表明,Zn HA-Zeo涂层不仅具有良好的耐腐蚀性能,而且具有良好的抗菌性能,可作为种植体应用的理想材料。

银-沸石掺杂羟基磷灰石镁合金涂层的生物活性、体外腐蚀行为和抗菌活性（英文）

Mg-based alloys received significant attention for temporary implant applications while, their applications have been limited by high degradation rate. Therefore, silver-zeolite doped hydroxyapatite(Ag-Zeo-HAp) coating was synthesized on Ti O_2-coated Mg alloy by physical vapour deposition(PVD) assisted electrodeposition technique to decrease the degradation rate of Mg alloy. X-ray diffraction(XRD) analysis and field emission scanning electron microscopy(FE-SEM) images showed the formation of a uniform and compact layer of Ag-Zeo-HAp with a thickness of 15 μm on the Ti O_2 film with a thickness of 1 μm. The potentiodynamic polarization(PDP) and electrochemical impedance spectroscopy(EIS) tests indicated that corrosion resistance of Mg-Ca alloy was considerably increased by the Ag-Zeo-HAp coating. The bioactivity test in the simulated body fluid(SBF) solution showed that a dense and homogeneous bonelike apatite layer was formed on the Ag-Zeo-HAp surface after 14 d. Investigation of antibacterial activity via disk diffusion and spread plate methods showed that the Ag-Zeo-HAp coating had a significantly larger inhibition zone(3.86 mm) towards Escherichia coli(E. coli) compared with the Ti O_2-coated Mg alloy(2.61 mm). The Ag-Zeo-HAp coating showed high antibacterial performance, good bioactivity, and high corrosion resistance which make it a perfect coating material for biomedical applications.镁基合金作为临时植入材料的应用受到了越来越多的关注,然而,由于其降解速率高,因此应用受到了限制。为了降低镁合金的降解速率,本文作者采用物理气相沉积(PVD)辅助电沉积技术在镀氧化钛(Ti O_2)的镁合金上涂覆掺银-沸石羟基磷灰石(Ag-Zeo-HAp)涂层。X射线衍射(XRD)分析和场发射扫描电镜(FESEM)图片显示,在厚度约为1μm的二氧化钛薄膜上形成了均匀且致密的Ag-Zeo-HAp涂层,厚度约为15μm。动电位极化(PDP)和电化学阻抗谱(EIS)测试表明,通过Ag-Zeo-HAp涂层,Mg-Ca合金的耐腐蚀性大大提高。模拟体液(SBF)浸泡测试生物活性试验结果表明,在14 d后的Ag-Zeo-HAp表面上形成了一层致密且均匀的类骨磷灰石层。采用琼脂扩散法和平板涂布法对抗菌活性进行研究。结果表明,与Ti O_2涂层的镁合金(2.61 mm)相比,Ag-Zeo-HAp涂层对大肠杆菌(E.coli)的抑制区(3.86 mm)明显增大。Ag-Zeo-HAp涂层具有良好的抗菌性能、良好的生物活性和耐腐蚀性,是生物医学应用的理想涂层材料。

Thermal Characteristics,Mechanical Properties,In Vitro Degradation and Cytotoxicity of Novel Biodegradable Zn-Al-Mg and Zn-Al-Mg-xBi Alloys

Ternary Zn-0.5A1-0.5Mg and quatemary Zn-0.5A1-0.5Mg-xBi （x = 0.1, 0.3 and 0.5） alloys were studied to evaluate the thermal and structural characteristics, mechanical properties, cytotoxicity and in vitro degradation behavior. Thermal analysis and microstructural observations showed that Zn-0.5A1-0.5Mg is composed of FCC-A1 ＋ HCP- Zn ＋ Mg2（Zn,A1）ll while a new phase a-Mg3Bi2 appeared after the addition of Bi to the Zn-0.5A1-0.5Mg ternary alloy. The results revealed that the quaternary Zn-A1-Mg-Bi alloys have higher tensile strength, elongation and hardness but slightly lower corrosion resistance than those of the temary Zn-AI-Mg alloy. Based on the MTT assay, the Zn-A1-Mg and Zn-A1-Mg-Bi alloys were found to be biocompatible, and thus, they can be considered for further investigation in an in vivo environment.

表面涂覆含氟羟基磷灰石和缺钙羟基磷灰石的镁合金体外降解行为(英文)

通过电化学沉积方法,在生物降解镁合金表面覆盖含氟羟基磷灰石(FHA)涂层和缺钙羟基磷灰石(CDHA)涂层。采用X射线衍射、傅立叶变换红外光谱、透射电子显微镜、扫描电子显微镜和能量色散X射线光谱研究涂层特性。结果表明:涂覆纳米FHA涂层的样品具有垂直于样品表面的纳米针状结构,比涂覆CDHA涂层样品的结构更致密和更均匀。纳米FHA涂层比纳米CDHA涂层具有更小的晶粒尺寸,分别为65 nm和95 nm。然而,CDHA涂层比FHA涂层更厚,厚度分别为19μm和15μm。通过极化、浸泡和析氢实验研究的腐蚀行为表明:纳米FHA涂层和纳米CDHA涂层显著降低腐蚀速率并引起钝化。纳米FHA和纳米CDHA涂层可以加速骨状磷灰石层的形成,相比未覆盖的镁合金可以显著减少溶出速率。纳米FHA涂层能对镁合金提供有效的防护并具有更高的腐蚀性能。因此,覆盖纳米FHA涂层的镁合金在整形外科领域具有良好的应用前景。

四元形状记忆合金Cu-Al-Ni-X(X=Mn,Ti)的显微组织和腐蚀特征（英文）

采用场发射扫描电子显微镜、透射电子显微镜、X射线衍射和差示扫描量热法,并在NaCl溶液中进行电化学和浸渍试验,研究添加不同含量的Mn或Ti(0.4%,0.7%,和1.0%,质量分数)对Cu-Al-Ni形状记忆合金的显微组织、形状记忆效应和腐蚀行为的影响。研究结果表明,显微组织、形状记忆效应和腐蚀特征对成分变化高度敏感。当添加0.7%Mn或0.7%Ti时,合金出现了最高的应变回复率。这可能是由于存在晶粒细化和高体积分数沉淀。电化学测试表明,在Cu-Al-Ni-Mn和Cu-Al-Ni-Ti形状记忆合金中氧化层的形成提供了良好的钝化保护,从而提高了合金的耐蚀性。浸渍试验表明,在Cu-Al-Ni-Mn形状记忆合金中,氧化层发生了点状腐蚀。腐蚀坑附近的腐蚀产物富Al/Mn氧化物而贫铜,而在腐蚀坑内腐蚀产物富铜。在Cu-Al-Ni-Ti形状记忆合金样品表面发生了局部腐蚀,而在基体中发生了脱铝腐蚀。