快凝Al—Fe—V—Si—Nd合金中亚稳相Al8Fe4Nd的价电子结构及 …

应用固体与分子经验电子理论,对快凝（ＲＳ）Ａｌ－Ｆｅ－Ｖ－Ｓｉ－Ｎｄ合金中的复杂相Ａｌ８Ｆｅ４Ｎｄ的价电子结构进行了计算分析,并研究了相变温度与键络断开温度的关系,计算显示在Ａｌ８Ｆｅ４Ｎｄ合金相中存在１２种共价键,Ｆｅ－Ｆｅ,Ａｌ（１）＿Ａｌ（１）,Ｆｅ－Ａｌ（２）,Ａｌ（１）－Ａｌ（２）键属于强键集团,Ｆｅ－Ａｌ（１）,Ａｌ（２）－Ａｌ（２）,Ａｌ（１）－Ａｌ（１）,Ｎｄ－Ａｌ（１）,Ｎｄ－Ａ     

Fe3Al合金晶体点阵的Mossbauer谱测定与分析

利用Ｍｏｓｓｂａｕｅｒ谱仪测定了Ｆｅ－２８Ａｌ和Ｆｅ－２８Ａｌ－５Ｃｒ合金ＤＯ３型晶胞的Ｍｏｓｓｂａｕｅｒ参数，结果表明，固溶元素Ｃｒ将取代ＤＯ３晶胞Ｉ、Ⅲ位置的Ｆｅ原子。利用上述结果，即可依据相关的电子理论对Ｆｅ３Ａｌ合金晶胞的价电子结构进行计算并建立其键络模型。     

Fe3Al合金的高温变形行为

用载荷松弛法对Ｆｅ－２８Ａｌ－２Ｔｉ合金在较高温度下的变形行为进行了研究．测定了Ｆｅ－２８Ａｌ－２Ｔｉ合金在高温变形时的载荷松弛曲线、应力减小因子Ｙ及激活能值,并对试样进行了显微结构观察．结果表明,Ｆｅ－２８Ａｌ－２Ｔｉ合金的高温变形是一个亚晶界吸收位错,而且不断向大角晶界转变的过程．     

原位反应生成Al-Fe/Al_2O_3,Al-Cu/Al_2O_3复合材料的过程原理

采用喷射共沉积法制备了Ａｌ－Ｆｅ２Ｏ３及Ａｌ－ＣｕＯ复合体，Ｆｅ和Ｃｕ的质量分数分别为９．６０％和５．５０％．在热处理过程中，随着温度由６００℃升高到８００℃和１０００℃，Ｆｅ３Ｏ４按Ｆｅ３Ｏ４ＦｅＯＦｅ顺序被还原，得到Ａｌ－Ｆｅ／Ａｌ２Ｏ３复合材料，其中Ｆｅ以Ａｌ１３Ｆｅ４相及ＡｌＦｅ相形式存在．Ａｌ２Ｏ３粒度为２～４μｍ均匀分布在基体中．Ａｌ／ＣｕＯ复合体在９００℃处理后，形成Ａｌ－Ｃｕ／Ａｌ２Ｏ３复合材料．文中对显微结构形成、反应进行的过程作了分析．     

2024铝合金涂覆Ni,Fe和Cu激光表面合金化

研究了２０２４铝合金涂Ｎｉ、Ｆｅ和Ｃｕ激光表面合金化，结果表明，在分别涂有Ｎｉ、Ｆｅ和Ｃｕ的合金层，分析形成了Ｎｉ３Ａｌ，Ｆｅ３Ａｌ，ＦｅＡｌ和Ｃｕ９Ａｌ４等金属间化合物，由于各种金属间化合物的形成，在合金化层与基体之间形成了无孔洞、无夹杂的冶金结合使金表面硬度提高２－３倍。     

快凝Al-Fe-V-Si-Nd合金中亚稳相Al_8Fe_4Nd的价电子结构及相变温度

应用固体与分子经验电子理论,对快凝(ＲＳ)Ａｌ Ｆｅ Ｖ Ｓｉ Ｎｄ合金中的复杂相Ａｌ８Ｆｅ４Ｎｄ的价电子结构进行了计算分析,并研究了相变温度与键络断开温度的关系·计算显示在Ａｌ８Ｆｅ４Ｎｄ合金相中存在１２种共价键,Ｆｅ Ｆｅ,Ａｌ(１) Ａｌ(１),Ｆｅ Ａｌ(２),Ａｌ(１) Ａｌ(２)键属于强键集团,Ｆｅ Ａｌ(１),Ａｌ(２) Ａｌ(２),Ａｌ(１) Ａｌ(２),Ａｌ(１) Ａｌ(１),Ｎｄ Ａｌ(１),Ｎｄ Ａｌ(２)键为次强键,而Ｎｄ Ｆｅ,Ａｌ(２) Ａｌ(２)键是弱键·分析表明,Ａｌ８Ｆｅ４Ｎｄ的分解与Ｎｄ Ａｌ(１),Ｎｄ Ａｌ(２)的断键温度有直接的关系,当温度升高至３...     

Nd－Fe－B合金的组织与组成对其腐蚀行为的影响

研究了Ｎｄ－Ｆｅ－Ｂ合金的组织与组成对其腐蚀行为的影响。对Ｎｄ－Ｆｅ－Ｂ合金各主要组成相在纯水和ＮａＣｌ溶液中电位进行了测定，结果表明Ｅ（富Ｎｄ相）＜Ｅ（基体相）＜Ｅ（富Ｂ相）。Ｎｄ－Ｆｅ－Ｂ合金的腐蚀特征是晶界处的富钕相优先腐蚀，然后向晶粒内Ｎｄ２Ｆｅ（１４）Ｂ基体相扩展。环境腐蚀试验结果表明，Ｎｄ－Ｆｅ－Ｂ合金中加入Ｄｙ后，耐蚀性提高；加入Ａｌ后，则耐蚀性有所下降。     

合成渣对钢液吸氮的保护作用

在真空感应炉中研究了１６００℃渣层覆盖条件下气相中不同氮分压时,钢液中氮含量的变化。结果表明,钙基中性及氧化性渣,如ＣａＯ－Ａｌ２Ｏ３－ＳｉＯ２和ＣａＯ－Ａｌ２Ｏ３－ＳｉＯ２－ＦｅＯ可作为绝缘层有效地防止氮在钢液和气相间的传质。因为在上述渣中,氮的溶解量约在３０×１０＾－６￣８０×１０＾－６之间。     

硅酸铝短纤维增强铝硅合金复合材料的强度特性与界面结构

用挤压铸造法制备硅酸铝短纤维（Ａｌ２Ｏ３·ＳｉＯ２）增强铝硅（ＡｌＳｉ）合金复合材料,测试了复合材料的室温及高温强度,并利用透射电镜观察了Ａｌ２Ｏ３·ＳｉＯ２纤维与ＡｌＳｉ合金基体界面．结果表明：３％～１０％的硅酸铝短纤维的加入使复合材料的室温及高温强度大大提高,在硅酸铝纤维与基体界面上存在两种反应物：一种物质是ＭｇＡｌ２Ｏ４,另一种物质含有Ｓｉ和Ｐ,且二者原子之比为３∶４,呈正交结构,点阵常数为ａ＝０．７１４ｎｍ,ｂ＝１．４２８ｎｍ,ｃ＝２．４０９ｎｍ．     

Fe3Al金属间化合物的价电子结构分析

依据固体与分子经验电子理论，对Ｆｅ３Ａｌ金属间化合物进行了价电子结构分析，建立了ＤＯ３型晶胞的键络模型，为揭示合金成分－结构－性能与Ｆｅ３Ａｌ合金相价电子结构的关系作了一些初步的尝试。     

乙二胺四乙酸二钠对钛合金表面羟基磷灰石涂层的影响

采用水热电化学方法在Ti6Al4V基体表面沉积羟基磷灰石（HA）涂层,研究乙二胺四乙酸二钠（EDTA-2Na）对HA涂层的物相组成、形貌、结合强度及生物相容性的影响.结果表明,电解液中无论添加EDTA-2Na与否,水热电化学沉积得到的仍为结晶度较高、生物相容性较好的HA涂层;不同的是,与不添加EDTA-2Na的涂层相比,添加EDTA-2Na后沉积得到的HA晶体形貌发生较大改变.随着EDTA-2Na浓度的增加,HA晶体从长薄片状到花瓣状以及纤维带状;HA涂层（002）晶面衍射峰强度随着EDTA-2Na浓度的增加逐渐减弱,涂层厚度也随之减小;HA涂层与基体的结合强度,随EDTA-2Na浓度的增加先增大后减小,在浓度为7.5×10^-4 mol·L^-1时达到最大值16.8 MPa.     

Al-Mg-Sc合金的价电子结构计算

运用固体经验电子理论（EET）,计算掺微量Sc前后的Al-Mg合金的价电子结构,计算表明,Sc的掺入将引起Al-Sc,Mg-Sc原子的较强相互作用,形成了Al-Sc晶胞偏聚区,从而提供了Al3Sc相形成所需要的成分条件,由此导致析出大量的Al3Sc将有效地细化晶粒。     

Al/Pb-WC-ZrO2复合电极材料的电化学性能研究

 研究了电镀液中固体微粒质量浓度及工艺条件对Al/Pb-WC-ZrO₂复合电极材料的表面化学组成及稳态析氧极化曲线的影响规律,对上述工艺条件进行了优化,优化后的工艺条件如下:WC:50 g/L,ZrO₂:40g/L,温度:20℃,电流密度:1.5 A/dm²,电沉积时间:2 h.所获得Al/Pb-WC-ZrO₂复合电极材料的析氧动力学参数为:a=771 mV,b=140 mV,i⁰=3.11×10^-6A·cm^-2,并且电极的析氧过电位为η=1 009 mV,复合镀层中WC和ZrO₂质量分数分别为10.02%和3.55%.     

Defect properties of GaAs by positron annihilation

Positron lifetime and Doppler Broadening spectra have been measured for three types of GaAs semiconductors. Direct evidence of native vacancy-type defects is found in the semi-insulating (SI-type) and n-type sample as its average lifetime {ie45-1} andS-parameter are larger than the bulk value. No positron trapping occurred in p-type GaAs. The lifetime spectrum of n-GaAs has also been measured as a function of temperature. The increase in average lifetime {ie45-2} from 226 ps to 234 ps at the temperature range 95–330 K was observed and was explained by the ionization of the vacancy. The slight increase in bulk lifetime {ie45-3} with the temperature was caused by the lattice expansion and expansion coefficient α=14×10⁻⁶K⁻¹ was evaluated. Chen Zhiquan: born in May 1969, Ph.D. graduate student. Current research interest is in positron annihilation. Supported by the National Natural Science Foundation of China     

Rapid dendrite growth in quaternary Ni-based alloys

Dendritic growth is one of the most common micro-structural formation mechanisms during crystal growth. Its morphology provides the kinetics information of crystal growth. Therefore, it is valuable to perform the research on rapid dendrite growth in order…     

Directional solidification and physical properties measurements of the zinc-aluminum eutectic alloy

Zn-5wt% Al eutectic alloy was directionally solidified with different growth rates (5.32–250.0 μm/s) at a constant temperature gradient of 8.50 K/mm using a Bridgman-type growth apparatus. The values of eutectic spacing were measured from transverse sections of the samples. The dependences of the eutectic spacing and undercooling on growth rate are determined as λ=9.21V-0.53 and ΔT=0.0245V0.53, respectively. The results obtained in this work were compared with the Jackson-Hunt eutectic theory and the similar experimental results in the literature. Microhardness of directionally solidified samples was also measured by using a microhardness test device. The dependency of the microhardness on growth rate is found as Hv=115.64V0.13. Afterwards, the electrical resistivity (r) of the casting alloy changes from 40×10-9 to 108×10-9 Ω·m with the temperature rising in the range of 300–630 K. The enthalpy of fusion (ΔH) and specific heat (C_p) for the Zn-Al eutectic alloy are calculated to be 113.37 J/g and 0.309 J/(g·K), respectively by means of differential scanning calorimetry (DSC) from heating trace during the transformation from liquid to solid.     

广西北海大冠沙白骨壤树上大型固着动物的数量及其分布

本文研究了广西北海大冠沙白骨壤树上大型固着动物的种类组成、数量分布特点及其对植物体的危害。结果表明,大冠沙白骨壤群落中的大型固着生物有10种,分属3门4纲6科,其中在白骨壤植株上的主要种类为白条小藤壶、潮间藤壶、褶牡蛎和黑荞麦蛤4种。危謇程度最大的是白条小藤壶,其湿重生物量占总湿重生物量的百分比高达72.3%～100%。受害程度最大的是向海林带的枝和叶,其动物生物量干重与植物生物量干重的比值(a/p)可达30.49×10~(-2)和30.43×10~(-2)。就整个红树林区而言,危害程度为向海林带(21.68×10~(-2))>中间林带(7.88×10~(-2))>向陆林带(0.01×10~(-2)).同一林带的植株受害程度为较低树层的大于较高树层的.密度和生物量的分布也与此相类似.     

An explanation to the high efficiency ofm-THPC (temporfin) used in photodynamic therapy

Meso-tetrahydroxylphenyl chlorin (m-THPC) is one of the most efficient prospective sensitizers used in photodynamic therapy (PDT). ESR spectroscopy, fluorescence quenching experiments and cyclic voltammogram measurement were used to study its redox properties. The results showed that the ability of m-THPC generating superoxide radical anions was very strong, and the rate constant of m-THPC fluorescence quenching by oxygen k_q (O₂)=1.46×10¹⁰ mol^-1·s^-1. The values of fluorescence quen- ching rate constant of m-THPC by some other electron acceptors, such as methyl viologen (MV²⁺) and anthraquinone (An), were also measured. And they were k_q (MV²⁺)=5.51×10⁹ mol^-1·s^-1, k_q (An)=7.81×10⁹ mol^-1·s^-1. The oxidation potential of m-THPC was examined to be +0.62 V (vs. NHE) in acetonitrile. All these suggested that m-THPC should be a much stronger electron donor than photofrin, the currently used in clinical photodrug, and may react easily through electron transfer with biological matter to yield various radicals. So it seemed reasonable that the type Ⅰ reaction may play an important role in the high activity of m-THPC-PDT.     

季铵盐改性MWNTs制备具有抗菌性和自清洁性的PVDF超滤膜

叔铵盐2-二甲氨基氯乙烷盐酸盐(DCH)作为季铵盐的前驱体,通过环氧氯丙烷接枝到氧化多壁碳纳米管(O-MWNTs)上,得到的季铵盐改性多壁碳纳米管(MWNTs)(即N~+-MWNTs)作为添加剂加入铸膜液制备聚偏氟乙烯(PVDF)平板超滤膜(PVDF/N~+-MWNTs膜).场发射扫描电子显微镜(FESEM)用来观测不同的N~+-MWNTs添加量对膜形貌的影响.结果表明,制得的PVDF/N~+-MWNTs复合膜表面粗糙度明显减小,同时亲水性得到明显改善.在对牛血清白蛋白(BSA)的污染-清洗循环实验中,PVDF/N~+-MWNTs复合膜相比于纯PVDF膜,纯水通量由110.5×10~(-5)L·m~(-2)·h~(-1)·Pa~(-1)上升至197.4×10~(-5)L·m~(-2)·h~(-1)·Pa~(-1).此外,通量恢复率(FRR)明显提高,尤其在3次循环之后,对BSA的截留性能没有下降.在对大肠杆菌和金黄色葡萄球菌的抗菌实验中,PVDF/N~+-MWNTs复合膜展现出优异的抑菌性,且在膜的抗菌性再生循环中,3次循环之后PVDF/N+-MWNTs复合膜的抑菌率依然维持在较高的水平.     

Experimental measurement of valence electron concentration of icosahedral AlPdMn quasicrystal

The valence charge density distribution for the icosahedral AlPdMn (i-AlPdMn) quasicrystal was obtained with the structure factors of the nine strongest symmetry inequivalent reflections, which were refined by using the quantitative convergent beam electron diffraction (QCBED) technique. It shows that the bonding charge is localized. The enhanced charge density in the middle of the aluminum-transition-metal (Al-TM) bond shown in the valence charge density distribution is the characteristic of covalent bonding. Assuming that the shape of an atom is a sphere with covalent radius, the number of electrons that each atom gains or loses in 55 different pseudo-Mackay clusters (PMCs) was calculated based on the obtained valence charge density distribution. It indicates that almost all the atoms lose electrons except a few Pd atoms that are in some particular shells. It also shows that the atoms of an identified element could have different valences because of chemically and/or structurally different local environments in which the atoms situate. Regardless of the topology and chemical occupancy, the number of valence electrons per atom in a cluster is close to 1.69. This strongly suggests that the pseudo-Mackay clusters are stabilized at a certain electron concentration. Biography: YU Fengmei (1965–), female, Professor, Ph.D., research direction: quasicrystal physics.