Effect of temperature on deformation behavior and microstructures of TC11 titanium alloy

The isothermal compression deformation behavior of TC11 titanium alloy with beta microstructure was studied between 750 °C and 1100 °C under the strain rate ranging from 0.001 s⁻¹ to 10 s⁻¹ by THERMECMASTOR-Z simulator. In addition, the effect of temperature on microstructure was observed using optical microscope. The results showed that the temperature greatly affected the flow stress and microstructure of TC11 titanium alloy cooled from beta phase region in air. During hot deformation of TC11 titanium alloy, the steady state flow characteristic was observed at higher temperature or lower strain rate. In the α + β phase region, spheroidization fraction of α lamellar decreased with increasing temperature, while in near-β and β phase regions, dynamic recrystallization fraction increased with increasing temperature in all strain rates except at the strain rate of 0.001 s⁻¹.     

The influence of beryllium addition on the microstructure and mechanical properties of Al-15%Mg2Si in-situ metal matrix composite

The effects of Beryllium (Be) on the microstructure and mechanical properties of Al-15%Mg₂Si composite were investigated. The results showed that with the increase of Be content, the average size and volume fraction of primary Mg₂Si particles decreases. Pseudo-eutectic Mg₂Si has mainly a fine fibrous structure in both specimens with and without Be. However, in the samples containing Be, the path for crack propagation along cell boundaries is very tortuous. Meanwhile, β_Al-Mg-Be phase based on a β-Al₃Mg₂ phase of the Al-Mg system was observed in specimens containing Be. It was found that with the addition of Be the ultimate tensile strength (UTS) and elongation values improved. A study of the specimen's fracture surfaces via scanning electron microscope revealed that Be increases the number of fine dimples and decohered Mg₂Si particles.     

小角X射线散射技术在材料研究中的应用

小角X射线散射(SAXS)是一种有效的材料亚微观结构表征手段。简单介绍了小角X射线散射理论,并综述了小角X射线散射技术在材料研究中的应用,内容涉及纳米颗粒尺寸测量,合金中的空位浓度、合金中的析出相尺寸以及非晶合金中的晶化析出相的尺寸测量,高分子材料中胶粒的形状、粒度以及粒度分布测量,以及高分子长周期体系中片晶的取向、厚度、结晶百分数和非晶层厚度的测量等等。     

PEG-IPDI-DMPA嵌段离聚体的合成与表征及其在水相中的溶液行为

采用溶液聚合法合成了PEG-IPDI-DMPA嵌段离聚体,通过FTIR、1H-NMR、GPC、DSC、TEM对其结构进行了表征;并通过粒径、比浓粘度、旋转粘度和电导率,对其在水相中的溶液行为进行了研究。红外光谱分析证实,合成获得了预期的聚氨酯结构嵌段离聚体;差示扫描量热分析证明,离聚体分子链段是由硬段和软段两相组成的嵌段共聚物;经透射电镜观察,嵌段离聚体在水溶液中呈现出较为规整的球形粒子状态。PEG-IPDI-DMPA嵌段离聚体粒径都在200nm左右;PEG-IPDI-DMPA嵌段离聚体是剪切变稀的。     

咪唑封闭水性聚氨酯复鞣剂的制备及表征

通过分子设计,以咪唑为封闭剂,1,6-己二异氰酸酯（HDI）、二羟甲基丙酸（DMPA）、2,2-二（4-羟基苯基）丙烷、聚酯二醇为原料制备出咪唑封闭水性聚氨酯复鞣剂（BPU）。用FT-IR、动态激光光散射（DLS）、TEM、TGA、DSC分别对BPU分子结构、乳胶粒形态及热性能进行了表征,分析了BPU复鞣剂的分子作用基础。结果表明产物分子结构中出现了羧基、咪唑环和聚氨酯结构;乳胶粒呈较为规则的、具有核壳结构的球形,粒径的多分散性是BPU具有良好选择填充性的微观原因。TGA和DSC分析显示BPU耐热性较高并随封闭率增加而略有降低;BPU解封温度范围为107.5～124.5℃,峰值为115.1℃;应用过程中BPU解封程度极低,利于助染性能的提高。     

Sb掺杂Sn_2S_3薄膜的制备及光学特性

真空蒸发制备Sb掺杂Sn2S3多晶薄膜(玻璃衬底),研究不同比例Sb掺杂对Sn2S3薄膜的结构、表面形貌、化学组分及光学特性的影响。实验给出5%掺Sb的薄膜经380℃热处理30min(氮气保护)得到正交晶系的Sn2S3∶Sb多晶薄膜,薄膜表面颗粒大小均匀,膜面致密有轻微颗粒聚集现象。薄膜体内Sn与S化学计量比为1∶1.49,掺Sb后为1∶0.543,薄膜中Sn、S、Sb分别以Sn2+、Sn4+、S2-、Sb5+存在。纯Sn2S3薄膜的光透过率在350~500nm波长范围内基本为零,随着波长增大,光透过率增加,其直接光学带隙为2.2eV,吸收边为564nm;掺Sb后薄膜的光透率明显降低,光学带隙为1.395eV比未掺杂时减小0.805eV,吸收边发生红移为889nm。     

BiFeO_3的水热合成、表征及光催化性能研究

以Bi(NO3)3.5H2O和Fe(NO3)3.9H2O为原料,KOH为矿化剂,聚乙二醇6000为分散剂,水热合成了单相BiFeO3粉体,利用X射线衍射、扫描电镜优化了水热合成条件,利用振动样品磁强计测定了BiFeO3的磁滞回线,并对产物进行了光催化降解甲基橙性能的研究。结果表明,200℃条件下反应6h制备的BiFeO3粉体显顺磁性,紫外光照射4h对甲基橙的降解率可达90%。     

硬脂酸凝胶法制备尖晶石型铁酸锌及其表征

采用硬脂酸凝胶法制备出ZnFe2O4纳米晶体,通过傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)、扫描电镜(SEM)及能谱分析(EDS)对产物进行了表征.研究表明,用硬脂酸凝胶法制得的铁酸锌晶体为尖晶石型,颗粒大小均匀,形貌大致呈球形,其粒径分布在10～36nm;该法具有混合均匀、操作简单、化学计量易于控制以及...