THE EFFECT OF PHYSICAL AGING ON α-RELAXATION PEAK IN PS

用内耗方法分析了非晶聚合物聚苯乙烯（ＰＳ）的物理老化对动态力学弛豫过程中的主转变内耗峰（α峰）的影响，说明老化过程（时效）和α峰的参数变化之间存在着规律性的联系．从另一方面证明了前人通过热焓分析和微蠕变等静力学参量分析得到的非晶聚合物老化过程的规律，特别是说明了老化过程对在玻璃化转变温度（Ｔｇ）以上的α峰参数的影响原因是存在着一个与α峰相叠加的过程内耗峰（淬火峰）．     

EFFECT OF VANADIUM ON THE NEEL TEMPERATURE AND RESISTIVITY OF γ-Fe-Mn AND γ-Fe-Mn-Al ALLOYS

<正> 1 引言γ-Fe-Mn 合金与Cr 均系典型的巡游电子能隙型反铁磁性物质。出于反铁磁性理论研究及发展反铁磁新功能合金的需要,较系统地研究过Al、Si、Cr 及Mn 对γ-Fe-Mn 基合金顺磁-反铁磁性转变及电阻率反常行为的影响。Al、Si 为非过渡族元素,Mn、Cr 为反铁磁性元素,如进一步研究周期表中位于Mn、Fe 左侧的3d 电子未满顺磁性元素V 的影响是有一定意义的,但迄今尚未见报道。     

THE EFFECT OF TENSION ON THE PROPERTIES OF CARBON FIBER FROM RAYON PRECURSOR

用ＴＧＡ、Ｘ－ｒａｙ衍射、密度试验等方法，研究了在不同张力状态下，粘胶纤维热处理过程中的结构与机械性能。发现减小张力能够获得性能较好的炭纤维（ＣＦ）。     

THE DEFECTS ONα_2-γINTERFACES IN THE Ti(AlMn)INTERMETALLIC COMPOUND

在Ｔｉ（ＡｌＭｎ）中有两种不同层次的层状结构。ＨＲＥＭ观察分析表明在这两种不同层次的层状结构中α２－γ相界面具有台附特征并可以用Ｏ点阵理论来解释。在细层次中的α２－γ片层具有一定的弹性形变，因而α２－γ仅有少量的台阶位错。另外，在细层次的α２－γ复合界面上，还发现层错桥连两个台阶位错的复合缺陷，结构，所有这些结果都表明细层状结构在形变的过程中具有集体行为。     

EFFECT OF HYDROGEN ON THE MICROSTRUCTURE OF SUPER-α2 ALLOY WITH β SOLUTION AND AGEING TREATMENT

借助透射电镜和Ｘ射线衍射仪探讨了氢对Ｓｕｐｅｒ－α２合金β固溶后时效组织的影响，结果表明，氢使时效组织显著细化，使析出相呈细小板条状规则排布，此外，氢还促进Ｂ２相转变为Ｏ相。     

长期时效对γ/γ′-αMo内生复合材料组织结构的影响

研究了长期时效对生长态γ/γ′-α~(Mo)内生复合材料的组织结构的影响。时效温度为750,850和950℃,时效时间长达1000h。研究发现,在750℃时效过程中,先后有 Ni_3Mo 亚稳相、Ni_2Mo 亚稳相和 Ni_3Mo 相出现。850℃时效,加剧了上述相变过程。在950℃时效,有σ-NiMo 和α~(Mo)相析出。所有试样的γ′相区变化都不明显,从而延缓了α~_(Mo)纤维的相变过程。     

STUDIES ON THE MECHANISM OF ELECTROLUMINESCENCE IN ORGANIC THIN FILMS

A high quality multilayer organic thin film electroluminescence (EL) device was prepared by LB film and vacuum evaporation technique. The uniform blue-green emission was observed under the positive DC voltage of less than20V in ambient room light. The mechanism of the EL device was discussed after measuring the Ⅰ—Ⅴcurves, absorption spectrum, fluorescent emitting spectrum and electroluminescent spectrum.     

ANALYSIS ON ROOM TEMPERATURE TENSILE STRENGTH OF δ-Al_2O_3, FIBER / Al-12Si COMPOSITE

对δ－Ａｌ２Ｏ３纤维／Ａｌ－１２Ｓｉ复合材料室温拉伸强度的分析表明，在实验条件下该复合材料存在δ－Ａｌ２Ｏ３纤维的最小体积分数Ｖｍｉｎ和临界体积分数Ｖｃｒｉｔ，并求出其基体强度δｍ和室温强度σｃ－δ－Ａｌ２Ｏ３纤维体积分数Ｖｆ直线方程及纤维的临界长度ｌｃ和复合材料的剪切应力τＰ确定复合材料的ＲＯＭ预测曲线，应首先判断σｍ是否等于未增强合金的强度σｕｍ才能得出正确的结论。     

STUDIES OF THE CHEMICAL STATES OF THE CARBONACEOUS DEPOSITS ON NI SURFACE WITH AES AND MOLECULAR BEAM TECHNIQUES

The chemical states of C on Ni (poly) were studied by AES and molecular beam techniques. These experiments were performed on a molecular beam-surface scattering apparatus. It is found that there are four different chemical states of C on Ni surface, i. e. carbidic C, graphitic C, CO adsorption and hydrogenateed C (CH x). The adsorbed CO and carbidic C are chemically active and can be hydrogenated with H_2 beam. But graphitic C is chemically inert and can not be hydrogenated with H_2 beam. The chemical states of hydrocarbon CH_x formed by a mixture beam of (CO H_2) on Ni are also studied. It is suggested that these species are intermediates of Fisher-Tropsch hydrocarbon synthesis.     

EFFECTS OF HYDROGEN ON THE α_2 /βTRANSUS TEMPERATURE AND LATTICE CONSTANT IN SUPER-α_2 ALLOY

用膨胀仪测定了含氢Ｓｕｐｅｒ－α２／β相变点；用Ｘ射线衍射仪探讨了氢对α２和β相晶格常数的影响。结果表明，随氢含量增加，Ｓｕｐｅｒ－α２的α／β相变点显著降低，β相晶格常数显著增大，α２相的晶格常数α增大，而Ｃ变化不大。     

EFFECT OF DOPING METHODS ON THE GAS-SENSING PROPERTIES OF α-Fe_2O_3

用化学沉淀法和升温水解法合成了纯α－Ｆｅ２Ｏ３和ＳｎＯ２掺杂的α－Ｆｅ２Ｏ３。用ＸＲＤ和ＴＥＭ研究了参杂方式对α－Ｆｅ２Ｏ３微观结构的影响。用静态气敏测试方法研究了掺杂方式对α－Ｆｅ２Ｏ３气体灵敏度和电阻的影响。结果表明：水解法α－Ｆｅ２Ｏ３颗粒微细（～４０ｎｍ），阻值适中（数百ｋΩ），而且气体灵敏度高。     

Microstructural and dimensional stabilities of a potential γ/γ′-α(Mo) directionally solidified eutectic superalloy under cyclic thermal exposure to 1000° C

A potential heat-resistant ductile eutectic composite,/-, in the Ni-Al-Mo ternary system has been thermally cycled in the temperature range 200 to 1000° C for up to 1000 cycles in an attempt to examine dimensional as well as microstructural stability of the composite under thermal fatigue conditions. The composite examined has two types of initial microstructure; in one, blocky -Ni₃Al encircles individual-Mo fibres (as-grown condition) whereas in the other, is in the form of fine cuboidal particles uniformly distributed in an Ni-rich fcc matrix (heat-treated condition). Dilatometric measurements upon temperature cycling show that the composite is stable against thermal ratchetting irrespective of initial microstructural conditions. However, the cycling induces microstructural change, which is characterized by segmentation of-Mo fibres or formation of a detrimental brittle phase identified as an intermetallic-NiMo that consumes-Mo fibres whether the fibres are encircled by or not. Post-cycling tensile tests at room temperature show that the fibre damage in the former has no fatal effect on tensile strength and ductility. A beneficial effect of the-encircling configuration is discussed on the basis of the recognition of a peritecto-eutectoid reaction:++ that has been disregarded.     

Effect of multiple strain-anneal cycles on the 1000° C creep behaviour of γ/γ′-α

An investigation of the influence of multiple strain-anneal cycles on the 1000° C creep behaviour of the directionally solidified eutectic alloy /- has been undertaken. Cycles consisted of swageing at room temperature or 900° C by about 5 to 10% per pass followed by annealing at 900° C, and were repeated to total strains of approximately 10, 30 and 50%. Transmission electron microscopy (TEM) of strain-annealed materials revealed that three-dimensional dislocation networks were introduced into the matrix, but very little work remained in the fibres. Constant-velocity creep testing indicated that all thermomechanical processing schedules improved the creep strength for strain rates 2 x 10^–6sec^–1; however only strain-annealing with a total of 13% work at room temperature (RT13) improved the behaviour at strain rates 2 x 10^–7sec^–1. The advantage of RT13 processing over as-grown materials at lower strain rates was confirmed by constant-load creep testing. It was also shown that 900° C annealing slightly improves the 1000° C creep properties in comparison to as-grown alloys. TEM of crept materials indicated that the active creep mechanism had been changed from dislocation pile-ups at fibres in as-grown alloys to dislocations being stopped by sub-boundaries in the matrix for RT13.     

INFLUENCE OF Nb ON THE MICROSTRUCTURE OF F_(e76.5-x) C_(u1)Nb_(x) Si_(13.5)B_9 NANOCRYSTALLINE STUDIED BY M■SSBAUER SPECTROCOPY

测量制备态和退火的Ｆｅ７６．５－ｘＣｕ１ＮｂｘＳｉ１３．５Ｂ９（ｘ＝０．１０、３．０、５．２、７．２）合金Ｍｏｓｓｂａｕｅｒ谱，结果表明，晶化后Ｎｂ、Ｂ等元素向晶界区扩散，在残余非晶形成了富Ｎｂ、Ｂ区和Ｎｂ、Ｂ区、Ｎｂ抑制非昌相的晶化和Ｆｅ２Ｂ相的析出，并对磁织构有一定的影响。     

Measurements of γ/γ' Lattice Misfit and γ' Volume Fraction for a Ru-containing Nickel-based Single Crystal Superalloy

A conventional X-ray diffractometer has been used to determine the γ/γ lattice misfit and γ volume fraction for a Ru-containing nickel-based single crystal superalloy at room temperature.The rocking curve was used to characterize the distribution of subgrains.The diffraction peaks obtained by ω-2θ scan were used to determine the γ/γ lattice misfit and γ volume fraction.A three peaks fitting model was proposed.The peak fitting results are in good agreement with the model.The X-ray diffraction results indicate that the nickel-based single crystal superalloy was not a perfect monocrystalline material,which is comprised of many subgrains;and each subgrain also consists of large numbers of mosaic structures.In addition,two anomalous reflection phenomena were found during the experiment and discussed with respect to their occurrence and impact on the measurement.The experimental results show that the γ/γ lattice misfit and γ volume fraction will be various at the different regions of its dendritic microstructure.The average γ/γ lattice misfit and γ volume fraction of the experimental alloy are approximately-0.2% and 70%,respectively.Furthermore,the γ volume fraction calculated by atom microprobe(AP) data is also basically consistent with the experimental results.     

STUDY ON_αTRANSITION OF ORIENTED,CRYSTALLIZED AND_γ-IRRADIATED PET WITH THERMALLY STIMULATED CURRENT

用拉伸、热处理和大剂量γ射线辐照的方法制备了一系列具有不同平面取向度、不同结晶度和不同分子链长度的PET 试样。短路热释电流温度谱显示对应于玻璃化转变的α峰随平面取向度、结晶度的增大向高温区移动;随γ辐照剂量的增大向低温区移动。随平面取向度和结晶度的提高,被冻结的大分子主链链段偶极热弛豫活化能减小,偶极热弛豫时间常数指数增长。γ辐照对偶极热弛豫运动的影响较小。     

Effect of swaging on the 1000‡C compressive slow plastic flow characteristics of the directionally solidified eutectic alloy γ/γ'′-α

Swaging between 750 and 1050 C has been investigated as a means to introduce work into the directionally solidified eutectic alloy /gg- (Ni-32.3 wt % Mo-6.3 wt % Al) and increase the elevated temperature creep strength. The 1000 C slow plastic compressive flow stress-strain rate properties in air of as-grown, annealed, and worked nominally 10 and 25% materials have been determined. Swaging did not improve the slow plastic behaviour. In fact large reductions tended to degrade the strength and produced a change in the deformation mechanism from uniform flow to one involving intense slip band formation. Comparison of 1000 C tensile and compressive strength-strain rate data reveals that deformation is independent of the stress state.     

A STUDY ON THE THERMAL STABILITY TO 1000°C OF VARIOUS CARBON ALLOTROPES AND CARBONACEOUS MATTER BOTH UNDER NITROGEN AND IN AIR

ABSTRACT

The thermal behavior of graphite, C₆₀ fullerene, fullerene black (carbon soot containing fullerenes), extracted fullerene black and diamond has been analyzed to 1000°C by TGA–DTA (thermogravimetric analysis and differential thermal analysis) under a nitrogen flow at a heating rate of 20°C/min. Very small weight losses have been recorded in the case of graphite and diamond. Furthermore no diamond graphitization has been observed. The sublimation of pure C₆₀ and the fullerene fraction of fullerene black (both pristine and extracted) has been observed and discussed.

The combustion reaction in air flow of graphite, C₆₀ and C₇₀ fullerenes, fullerene black (both unextracted and extracted), carbon nanotubes and diamond has been studied by TGA–DTA at a heating rate of 20°C/min. C₇₀ fullerene and fullerene black have been found to be the most reactive carbon materials with O₂. The role played by C₇₀ in the degradation of fullerites has been discussed. Among the carbon materials examined, the best resistance to O₂ attack has been shown by diamond and carbon nanotubes. The behavior of graphite is intermediate between diamond and fullerene blacks. The behavior of C₆₀ fullerene appears closer to that of graphite although it appears to be more reactive with O₂. Samples of graphite and carbon blacks N375 and N234 have been studied by TGA–DTA in air flow before and after a radiation treatment with neutrons or γ radiation. The effect of the radiation damage in the combustion reaction of these carbon materials has been discussed.     

FORMATION OF THE INTERFACE TRANSITION LAYER FOR SnO_2/Fe_2O_3 FILMS PREPARED BY PLASMA CVD

The influences of the thermal annealing to the gas-sensing properties of SnO_2/Fe_2O_3 multi-layer films, grown by plasma CVD, and to the structure of the transition interface layer between SnO_2 and Fe_2O_3 layers have been studied. The formation of the interface is attributed to the effects of the plasma during the deposition.     

Effects of temperature and ferromagnetism on the γ-Ni/γ′-Ni3Al interfacial free energy from first principles calculations

The temperature dependencies of the γ(f.c.c.)-Ni/γ′-Ni₃Al(L1₂) interfacial free energy for the {100}, {110}, and {111} interfaces are calculated using first-principles calculations, including both coherency strain energy and phonon vibrational entropy. Calculations performed including ferromagnetic effects predict that the {100}-type interface has the smallest free energy at different elevated temperatures, while alternatively the {111}-type interface has the smallest free energy when ferromagnetism is absent; the latter result is inconsistent with experimental observations of γ′-Ni₃Al-precipitates in Ni–Al alloys faceted strongly on {100}-type planes. The γ(f.c.c.)-Ni/γ′-Ni₃Al interfacial free energies for the {100}, {110}, and {111} interfaces decrease with increasing temperature due to vibrational entropy. The predicted morphology of γ′-Ni₃Al(L1₂) precipitates, based on a Wulff construction, is a Great Rhombicuboctahedron (or Truncated Cuboctahedron), which is one of the 13 Archimedean solids, with 6-{100}, 12-{110}, and 8-{111} facets. The first-principles calculated morphology of a γ′-Ni₃Al(L1₂) precipitate is in agreement with experimental three-dimensional atom-probe tomographic observations of cuboidal L1₂ precipitates with large {100}-type facets in a Ni-13.0 at.% Al alloy aged at 823 K for 4096 h. At 823 K this alloy has a lattice parameter mismatch of 0.004 ± 0.001 between the γ(f.c.c.)-Ni-matrix and the γ′-Ni₃Al-precipitates.