关键词： 镁合金   挤压态   退火态   腐蚀   析氢   电化学  

摘要： 镁合金的应用受到其变形能力差、耐腐蚀性差的制约。为推广镁合金应用,采用低合金化设计并制备了新型Mg-0.12Ca-0.08Ba合金,通过NaCl溶液浸泡试验、SEM、EDS分析和电化学测试等手段考察了其在3.5%NaCl溶液中的腐蚀行为。实验结果表明:随着腐蚀时间的延长,挤压态及挤压退火态Mg-0.12Ca-0.08Ba合金表面由局部点蚀变为大范围面腐蚀,腐蚀产物逐渐增多,腐蚀产物主要为MgO、Mg(OH)2,合金表面的线粗糙度、面粗糙度明显增大,析氢速率逐渐减小。与挤压态镁合金相比,退火态合金析氢速率较慢,开路电位更高,腐蚀电流更小,表明退火态合金耐腐蚀性能较好。

摘要： Magnesium (Mg) offers a tremendous weight saving potential as an advanced lightweight material in the automotive and aerospace industries. However, the application of Mg is limited by its low corrosion resistance and low mechanical properties especially at elevated temperature. To overcome the limitations of Mg, carbon nanotubes (CNTs) are considered to be ideal for the fabrication of Mg matrix composites due to their high aspect ratio and superior mechanical properties. However, the design of CNTs-reinforced Mg matrix composites requires a homogeneous dispersion of CNTs and a good interfacial bonding between the CNTs and the Mg matrix for an effective strengthening of the composites by CNTs. Consequently, the coating of CNTs is considered to be an effective strategy to improve the wettability of CNTs by Mg and promote the dispersion of CNTs in the metal matrix. In this work, a new technique was developed for the coating of CNTs with either SiOC or SiC using a polymethylhydrosiloxane (PMHS) precursor to enhance the properties of AZ91 composites. Initially, the transformation of PMHS to SiOC and SiC was established via a simple curing technique followed by pyrolysis in Ar at 900 and 1500 °C, respectively. Then, a preliminary application of PMHS as a coating precursor for CNTs found that SiOC can be coated on the individual CNTs as a discontinuous or continuous coating layer or precipitated densely on the CNTs agglomerates. The effect of coating concentration on the morphology and dispersibility of the CNTs were further studied through a more extensive production of SiOC and SiC coated CNTs. Intermediate coating concentration (i. e. 45-55 wt%) was found to be suitable for the wetting of CNTs by the AZ91. The addition of either SiOC coated CNTs or SiC coated CNTs had successfully led to a notable grain refinement by up to 66 % in grain size reduction, increase in hardness by up to 17 %, and increase in yield strength by up to 15 % in the AZ91 composites in comparison t

摘要： 随着我国生态文明建设和"双碳"行动的推进,绿色建筑成为建筑行业转型升级的必由之路.建筑模板作为建筑工程施工的重要材料,也必然要走绿色、低碳、可持续发展之路.全国政协委员、陕西省政协副秘书长贾正兰在调研中了解到,合金模板作为高周转、可循环利用的建筑材料,在行业发展中符合产业政策引领方向.

关键词： AZ91D镁合金   强制对流搅拌   流变压铸   组织演变   力学性能   热处理  

关键词： AZ31 镁合金   平面应变   EBSD   孪生变体  

关键词： Mg-Zn-Gd三元镁合金   凝固路径   冷却速率   计算模型  

关键词： 有机高分子材料   壳聚糖   羟基磷灰石   表面改性   复合水凝胶   生物相容性  

关键词： 金属材料   含铜钴铬合金   细胞毒性   细胞增殖   细胞凋亡   生物相容性  

关键词： 镁合金   晶粒细化   活性炭粉  

摘要： 研究了活性炭粉对Mg-3wt%Al、Mg-9wt%Al、AZ31和AZ91镁合金晶粒尺寸的影响。主要采用金相显微镜(OM)对添加活性炭粉的含铝铸造镁合金进行了显微组织分析。试验结果表明：铸造Mg-3wt%Al和Mg-9wt%Al的平均晶粒尺寸分别为365、340μm，添加1wt%的活性炭粉后晶粒尺寸分别减少到75、60μm。铸造态AZ31和AZ91镁合金的平均晶粒尺寸分别为325、285μm，添加1wt%的活性炭粉后晶粒尺寸分别减少到183、75μm。理论分析表明：铝元素与活性炭反应生成的Al4C3是理想的异质形核质点，异质形核质点的加入，起到了明显细化晶粒的效果。