稀土钕对激光快速成形TC4合金组织及性能的影响

针对氢化脱氢钛合金粉末氧含量较高的问题，研究了添加稀土钕对激光快速成形TC4合金组织及性能的影响。结果发现，添加稀土Nd后，激光快速成形TC4合金的宏观晶粒尺寸变化不大；但随稀土添加量的增加，初始β列状晶逐渐转化为全β等轴晶，晶粒内部的魏氏α组织逐渐转变为网篮α，粗化α条不断增多，呈现团束聚集趋势，晶界α集束体积分数也不断增大；随稀土添加量的增加，激光快速成形TC4合金的室温塑性先大幅度提高，然后急剧降低；稀土添加量为0．1％～0．2％（质量分数，下同）时，氧含量为0．26％的氢化脱氢TC4合金粉末激光快速成形件沉积态的抗拉强度达975MPa，延伸率9．5％，满足锻件标准要求。     

利用“球化效应”激光扫描制备球形Ti粉的研究

利用“球化效应”，在SLS设备上探索将异形Ti粉转化为高性能球形粉末的可行途径。通过系统地改变激光功率、扫描速度，以及选取合适的激光扫描间距，探明了形成“球化效应”的工艺条件，并在激光功率为600W，扫描速度为30mm／s时，获得了较为理想的球形Ti粉。通过对球化过程进行理论分析，得出了选取激光扫描制备球形Ti粉工艺参数的准则。     

Hydriding-dehydriding properties of Mg2Ni alloy modified by ball-milling in tetrahydrofuran

A new approach of ball-milled Mg2Ni in tetrahydrofuran (THF) to improve the hydriding kinetics of Mg2Ni alloy is suggested and studied. It is found that the modified alloy displayed the improved activity for hydriding even at relatively low temperature (e.g., 323-373 K). In the case of the sample milled in THF for 20 h, the hydrogen content (mass fraction) reaches 1.6 % at 323 K, 2.1% at 348 K and 3.4% at 448 K, respectively. The use of THF during grinding led to the change of the structure, which is reflected by the broadening and weakening of the diffraction peaks in the XRD spectra. The XPS analysis shows that Mg (2s) binding energy peak of Mg2Ni after modification shifted from a lower binding energy to a higher one, indicating the charge transference between Mg and THF and the formation of catalytically active electron donor-acceptor (EDA) complexes on the surface of modified Mg2Ni alloy.     

Microhardness and corrosion behavior in CrN/electroless Ni/mild steel complex coating

The electroless nickel–phosphorous (Ni–P) coating was chosen as an interlayer to improve the properties of the CrN/mild steel (MS) composite. A hypophosphite-reduced acid solution was used to first deposit electroless Ni–P onto MS substrates, and then the CrN overlayer was deposited by reactive r.f. magnetron sputtering onto the electroless Ni–P modified substrate. The electroless Ni–P layer crystallizes with the precipitation of a Ni₃P phase during r.f. sputtering, and thus a coating–substrate composite of CrN/Ni–Ni₃P/MS is formed. The electroless Ni–P coating increases the surface hardness of the steel substrate to more than three times. The surface hardness of the CrN coating modified by an electroless Ni–P interlayer exhibits a hardness higher than 2000 HK_0.015. The usual substrate effect on the microhardness of the coatings is nearly eliminated with the complex coating feature, and a significant enhancement of surface hardness in the coating assembly is achieved. The corrosion tests indicate that the Ni–Ni₃P/MS configuration exhibits a more positive E_corr value (i.e. less electronegative) than CrN/MS and the corresponding potential curve is shifted toward the low-current side, indicating a better anti-corrosion performance. Through comparison of the E_corr values and the polarization curves, it is demonstrated that the CrN/Ni–Ni₃P/MS composite exhibits significantly higher corrosion resistance than the Ni–Ni₃P/MS and CrN/MS coating configurations.     

锌铝超塑性合金超塑压缩试验研究

对Ｚｎ－２２％Ａｌ超塑性合金进行了等温超塑压缩试验。在相同的温度、变形速率条件下，研究了不同的变形强度与流动应力及硬度，以及在相同的温度、变形程度条件下，不同的变形速率与流动应力等的关系。     

高纯钨中杂质元素的化学光谱法测定

采用以一定比例的ＨＮＯ３和ＨＣｌ为介质，使钨沉淀成钨酸与杂质分离，然后用碳粉吸附杂质再进行光谱测定的方法，对高纯钨（包括金属钨、三氧化钨、钨酸、钨酸铵）中１５个杂质元素Ｆｅ、Ｎｉ、Ｃｕ、Ｍｎ、Ａｌ、Ｖ、Ｃｒ、Ｃｏ、Ｃａ、Ｍｓ、Ｐｂ、Ｓｎ、Ｂｉ、Ｃｄ、Ｂｅ进行了测定，取得了理想的结果，测定下限可达（０．１～０．５）×１０（－６）。     

铍材应力常数的X射线法测试

在X2001应力分析仪上采用悬臂梁加载法测试了可以用于铍的X射线应力测试的5个衍射晶面的应力常数。结果表明,铍的5个衍射晶面的应力常数差异较大，在进行X射线应力分析时．应采用相应衍射晶面的应力常数，才能获得准确的应力分析结果。由于X射线对铍有较大的穿透深度，必须考虑X射线穿透深度对应力常数标定的影响。     

Multi-Omics Revealed Molecular Mechanisms Underlying Guard Cell Systemic Acquired Resistance

Systemic Acquired Resistance (SAR) improves immunity of plant systemic tissue after local exposure to a pathogen. Guard cells that form stomatal pores on leaf surfaces recognize bacterial pathogens via pattern recognition receptors, such as Flagellin Sensitive 2 (FLS2). However, how SAR affects stomatal immunity is not known. In this study, we aim to reveal molecular mechanisms underlying the guard cell response to SAR using multi-omics of proteins, metabolites and lipids. Arabidopsis plants previously exposed to pathogenic bacteria Pseudomonas syringae pv. tomato DC3000 (Pst) exhibit an altered stomatal response compared to control plants when they are later exposed to the bacteria. Reduced stomatal apertures of SAR primed plants lead to decreased number of bacteria in leaves. Multi-omics has revealed molecular components of SAR response specific to guard cells functions, including potential roles of reactive oxygen species (ROS) and fatty acid signaling. Our results show an increase in palmitic acid and its derivative in the primed guard cells. Palmitic acid may play a role as an activator of FLS2, which initiates stomatal immune response. Improved understanding of how SAR signals affect stomatal immunity can aid biotechnology and marker-based breeding of crops for enhanced disease resistance.     

Adsorption characteristics of hexadecyl ammonium with different numbers of carbon chains in montmorillonite and the structure of the prepared composites

Journal of Porous Materials - The dynamics and thermodynamics of adsorption of hexadecyl ammonium with different numbers of carbon chains in montmorillonite (Mt) with different layer charge density...