标准号: T/CISA 146-2021

关键词： Fusion welding   magnesium alloys   solidification cracking   liquation cracking   grain refining  

摘要： As the lightest structural alloys, magnesium alloys offer significant potential for improving the energy efficiency of various transportation systems. The lack of sufficient weldability of Mg alloys is a crucial barrier to their potential use in safety-critical applications. Porosity formation, grain structure engineering, solidification cracking, liquation, and liquation cracking are the key metallurgical challenges to obtain reliable and robust fusion welds in Mg alloys. This critical review highlights the current understating regarding controlling the metallurgical phenomena during fusion welding of Mg alloys and discusses the unresolved metallurgical challenges to shed light on the path forward to enhance fusion weldability of Mg alloys.

关键词： SMAT   AZ91D   Double twinning   Corrosion   Isothermal calorimetry  

摘要： This article investigates the microstructure evolution and corrosion response of surface mechanical attrition treated (SMAT) AZ91D magnesium alloy. In-depth transmission electron microscopy and combined isothermal calorimetry and pressure measurement technique, a novel and powerful tool for in situ monitoring of the magnesium corrosion process, are explored in the present study. A gradient structured layer of similar to 500 mu m thickness with improved (similar to 2.5 times) surface hardness is successfully obtained on the AZ91D alloy surface. SMAT introduces compressive residual stress in the treated layer. TEM results confirmed nanoscale grains of similar to 125 nm in topmost region and multiple deformation twin-modes, including {10 (1) over bar2} < 10 (1) over bar1 > dense twins and {10 (1) over bar1} - {10 (1) over bar2} double twinning in SMATed layer. Twining of secondary twins is established in the TEM analysis. Moreover, a twin density gradient is evident within the treated layer, where it decreases with an increase in depth. After 24 h of immersion in 0.9% NaCl solution, the average corrosion rate of SMATed and non-SMATed specimens is similar to 11.0 and similar to 3.8 mm/year, respectively. The corrosion product on non-SMATed specimens has densely packed nano-flakes morphology;however, the SMATed surface shows two different morphologies: sparse nanowires and porous honeycomb-like structure. The SMATed specimen's lower corrosion resistance is attributed to the combined effect of the high density of defects, rougher surface, and smaller volume fraction of beta phase at the surface. (C) 2021 Elsevier B.V. All rights reserved.

关键词： 3D打印导航模板   微创髓芯减压   可注射人工骨   早期股骨头坏  

摘要： 目的:探讨3D打印导航模板辅助微创髓芯减压联合可注射人工骨治疗早期股骨头坏死的临床效果.方法:选取88例早期股骨头坏死患者随机分为研究组(44例,3D打印导航模板辅助微创髓芯减压联合可注射人工骨治疗)与对照组(44例,传统减压植骨术),对比两组手术效果等.结果:研究组恢复优良率明显高于对照组(P<0.05);研究组术后并发症发生率显著低于对照组(P<0.05).结论:3D打印导航模板辅助微创髓芯减压联合可注射人工骨治疗早期股骨头坏死效果确切,同时具有并发症少等优势.

关键词： Dual self-healing   Micro-arc oxidation   Corrosion inhibitor   Polyurethane   Disulfide bond  

摘要： In this work, a new self-healing composite coating for corrosion protection of magnesium (Mg) alloy, which is based on the dual actions of the corrosion inhibitor M-16 embedded in the micro-arc oxidation (MAO) coating and self-healing polyurethane (PU) modified by disulfide bonds, is developed. Electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) are used to study the anti-corrosion performance of the scratched and healed composite coatings immersed in 3.5 wt% NaCl solution. Results show that the porous MAO coating is suitable to carry inhibitor M-16 and the anti-corrosion performance of the scratched coating is significantly improved by the inhibitor embedded in the MAO coating. The scratched coating exhibits an excellent recovery of the anti-corrosion performance after the heat treatment, which is attributed to the cooperation of dynamic disulfide bonds and shape-memory effect of the self-healing PU coating. Furthermore, it is found that the inhibitor M-16 embedded MAO coating can enhance the repair ability and anti-corrosion performance of the PU coating when the corrosion product was pre-formed inside the scratch of the composite coating.

关键词： Fe-based amorphous coatings   Magnesium alloy   Interfacial characteristic   Bonding strength   Corrosion resistance  

摘要： Due to the susceptibility to corrosive environment, it is necessary for the surface protection of magnesium alloy. Fe-based amorphous coatings are deposited on the surface of WE43 magnesium alloy with a Ni60 interlayer which is fabricated by the high velocity oxy-fuel (HVOF) spraying. The interfacial characteristic, microstructure and properties as bonding strength, wearing and corrosion resistance of the amorphous coating are investigated. The results indicate that the Fe-based amorphous coating with high amorphous content and low porosity is attained on WE43 magnesium alloy, and a metallurgical bonding between the lamellar structures is identified by transmission electron microscopy (TEM). The bonding strength between amorphous coating and magnesium substrate exceeds 56 MPa. Comprehensive corrosion resistance of coatings is superior than stainless steel in 0.1 mol/L HC1 solution. The coefficient of friction is only half of that WE43 magnesium alloy. Therefore, the Fe-based amorphous coating shows a potential application for surface protection of magnesium alloy in chloride environment.

关键词： Mg-3Al-1Zn-0.2Mn镁合金   轧制变形量   导电率   轧制  

摘要： 采用金相显微镜、万能试验机、导电率测量仪研究轧制温度360℃下18%~55%轧制变形量对铸态Mg-3Al-1Zn-0.2Mn镁合金的显微组织和性能的影响。结果表明:铸态合金组织明显为枝晶,晶界处有大量Mg17Al12金属间化合物分布。随着轧制变形量的增加,合金中晶粒越来越细化,组织越来越均匀。与铸态合金相比,轧制合金的强度和伸长率均明显提高,导电率明显降低。变形量55%的合金抗拉强度和屈服强度达到最大值,分别为325、234 MPa,其伸长率和导电率分别为24.7%和17.20%IACS。

关键词： 医用功能纸   聚乙二醇甲基丙烯酸酯   聚合物刷   原子转移自由基聚合   生物相容性  

摘要： 为改善纤维素基纸张材料的生物相容性,本研究通过表面引发原子转移自由基聚合技术,将聚乙二醇甲基丙烯酸酯聚合物刷接枝到纸张表面制备医用功能纸,并对聚乙二醇甲基丙烯酸酯聚合物刷在纸张表面的接枝效率及其生物相容性进行了研究。结果表明:采用表面引发原子转移自由基聚合技术可有效地将聚乙二醇甲基丙烯酸酯聚合物刷接枝到纸张表面,且整个接枝过程活性可控;相比原纸,接枝聚乙二醇甲基丙烯酸酯聚合物刷纸张的抗血细胞黏附能力明显增强,补体激活显著改善,细胞毒性显著降低,呈现出良好的生物相容性。

关键词： 弹性蛋白   伤口敷料   生物降解性   生物相容性   生物医学   临床前试验   耐用性   纳米纤维  

摘要： 科学家开发实验性伤口敷料,近日,德国研究人员开发了一款基于弹性蛋白原的定制生物医学适用材料。该材料结合了生物相容性、耐用性、生物降解性和类似于皮肤的良好机械性能。临床前试验证实,它适合用作治疗慢性和复杂伤口的伤口敷料材料。研究人员利用电纺工艺生产出超薄的弹性蛋白原纳米纤维,然后将其相互交联,形成一片类似弹性蛋白的材料。

关键词： 变形镁合金   预时效   显微组织   力学性能  

摘要： 与铸造镁合金相比,变形镁合金可获得更高的强度、更好的延展性以及更多样化的力学性能,从而满足多样化镁合金结构件的应用需求。但由于变形镁合金绝对强度低、塑性变形能力差,其应用范围受到了极大的限制。近期研究发现,对变形镁合金进行预时效处理能够显著提高合金的综合力学性能,因此总结和归纳预时效对变形镁合金的影响具有重要的理论参考价值和实践指导意义。预时效是在塑性加工前进行时效处理的一种时效方法,预时效处理可通过欠时效、峰值时效和过时效等工艺调控析出相的大小、形状、分布和位向,析出相在后续的加工变形过程中具有改善材料组织与性能的重要作用。预时效提供的析出相,在后续塑性加工变形过程中为动态再结晶提供形核核心,促进动态再结晶,细化晶粒,激活非基面滑移,弱化基面织构,且晶界析出相可显著抑制晶粒长大,有效阻碍位错运动,也可使位错累积增多,小角度晶界增多。此外,增加析出相含量能减小晶粒尺寸,抑制{1012}拉伸孪晶的形核和长大,增加{1011}压缩孪晶和{1011}-{1012}双孪晶含量,这些孪晶增加了动态再结晶的形核核心,改变了晶粒取向,进而大幅提高了合金的强度、屈服应力和峰值应力,同时也保证了合金的延展性,极大地改善了镁合金的综合力学性能。本文针对Mg-Al系、Mg-Zn系、Mg-Sn系和Mg-RE系等四系合金,总结分析了预时效对变形镁合金组织与性能的影响,着重从压缩、拉伸、挤压和轧制等变形工艺角度进行综述,为制备综合力学性能优良的镁合金提供参考。此外,本文指出了预时效变形镁合金在未来的发展动态和研究重点。