晶体材料内部残余应力衍射法无损检测的研究进展

目前能够准确、无损地测试材料内部残余应力的手段主要是中子衍射和同步辐射,但这两种测试手段需要核反应堆或高能同步辐射源,投资巨大,只为少数发达国家的少数实验室所拥有,难以应用到实际生产中。短波长X射线衍射仪通过钨靶-K_α特征射线(波长约0.02 nm)以及独特的谱接收方式,达到或接近同步辐射及中子衍射对晶体材料内部晶格应变的无损定点测试,为内部残余应力无损检测的广泛应用开辟了一条新的渠道。介绍了中子衍射和同步辐射对残余应力测试的国内外研究现状,重点展示了短波长X射线衍射仪用于内部应力测试的结果,并就三种测试方法特点进行了对比分析。     

Gold supported on metal oxides for carbon monoxide oxidation

Au has been loaded (1% wt.) on different commercial oxide supports (CuO, La₂O₃, Y₂O₃, NiO) by three different methods: double impregnation (DIM), liquid-phase reductive deposition (LPRD), and ultrasonication (US). Samples were characterised by N₂ adsorption at −196 °C, high-resolution transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectrometry, high-angle annular dark-field imaging (Z-contrast), X-ray diffraction, and temperature programmed reduction. CO oxidation was used as a test reaction to compare the catalytic activities. The best results were obtained with Au loaded by DIM on the NiO support, with an activity of 7.2 × 10⁻⁴ mol_CO·g_Au ⁻¹·s⁻¹ at room temperature. This is most likely related to the Au nanoparticle size being the smallest in this catalyst (average 4.8 nm), since it is well known that gold particle size determines the catalytic activity. Other samples, having larger Au particle sizes (in the 2–12 nm range, with average sizes ranging from 4.8 to 6.8 nm), showed lower activities. Nevertheless, all samples prepared by DIM had activities (from 1.1 × 10⁻⁴ to 7.2 × 10⁻⁴ mol_CO·g_Au ⁻¹·s⁻¹, at room temperature) above those reported in the literature for gold on similar oxide supports. Therefore, this method gives better results than the most usual methods of deposition-precipitation or co-precipitation.      

角度分散法中子衍射应力测试技术的应用

由于中子具有较高的穿透能力,利用中子衍射容易获得块状试样内部特定位置的三维点阵面间距,从而实现应变/应力分布的较准确评价。首先介绍了各种应力测试技术的研究现状以及角度分散法中子衍射应力测试技术的基本原理;然后结合冲压成型试样的强度评价、复层钢板拉伸变形后的残余应变评价以及负荷条件下钢筋混凝土中钢筋的应力分布等中子衍射典型试验研究,说明角度分散法中子衍射应力测试技术在国外已广泛应用于工程结构件与材料内部应力的定量研究;最后展望了角度分散法中子衍射应力测试技术在国内的研究前景。     

Structural characterization of lead sulfide thin films by means of X-ray line profile analysis

X-ray diffraction patterns of chemically deposited lead sulphide thin films have been recorded and X-ray line profile analysis studies have been carried out. The lattice parameter, crystallite size, average internal stress and microstrain in the film are calculated and correlated with molarities of the solutions. Both size and strain are found to contribute towards the broadening of X-ray diffraction line. The values of the crystallite size are found to be within the range from 22–33 nm and the values of strain to be within the range from 1·0 × 10⁻³–2·5 × 10⁻³.     

Dynamic contact strain measurement by time‐resolved stroboscopic energy dispersive synchrotron X‐ray diffraction

Recent developments of synchrotron X‐ray sources and dedicated high‐energy beamlines are now enabling strain measurements from large volumes of industrially relevant metallic materials. Such capability is allowing the validation of novel and alternative nondestructive experimental methods of strain measurement or computational models of complex deformation processes. This study describes the first dynamic contact strain measurement of a ball bearing using stroboscopic energy dispersive X‐ray diffraction. The experiment probed the dynamic contact strain in the outer raceway of a test bearing. The inner raceway of the bearing was attached to a shaft rotating at 150 revolutions per minute, and the outer raceway, where the measurements were made, was fixed in a stationary bearing housing. A triggering system was used to synchronise the data acquisition of the energy dispersive X‐ray diffraction detector with the bearing rotation. Specifically, diffraction data were acquired, stroboscopically, from the material volume within the raceway, in a known location, when the ball was positioned directly below it. A total of 20 s of accumulated diffraction signal was recorded, acquiring 2 ms of data per revolution, providing diffraction patterns of sufficient quality for the dynamic contact strain to be measured. Macromechanical stress field was calculated from the micromechanical strains measured from five lattice planes. This allowed a comparison of the experimentally measured stress field and that of finite element simulations. Good agreement was observed between the finite element results and experimental measurements indicating the applicability of this novel dynamic strain measurement technique for tribological systems.     

A non-destructive method for the measurement of residual strains in semi-crystalline polymer components

A new non-destructive tool is presented, enabling the measurement of locked-in residual strains in semi-crystalline polymer-based components. The technique employs high-energy synchrotron X-rays to probe the variation of diffraction angle within a well-defined ‘gauge volume’ with a spatial resolution of the order of 1 mm. Lattice strain is calculated from the diffraction angles.An overview of the experimental methodology and underlying principles involved in the non-destructive evaluation of residual strain in polymer-based components is given. Preliminary results show that synchrotron X-rays can be used successfully to measure the internal elastic residual strain field in polymer components, being potentially applicable to other materials. The method was used successfully to measure residual strains in a commercial high density polyethylene gas pipeline sample.     

Stress‐Actuated Spiral Microelectrode for High‐Performance Lithium‐Ion Microbatteries

Miniaturization of batteries lags behind the success of modern electronic devices. Neither the device volume nor the energy density of microbatteries meets the requirement of microscale electronic devices. The main limitation for pushing the energy density of microbatteries arises from the low mass loading of active materials. However, merely pushing the mass loading through increased electrode thickness is accompanied by the long charge transfer pathway and inferior mechanical properties for long‐term operation. Here, a new spiral microelectrode upon stress‐actuation accomplishes high mass loading but short charge transfer pathways. At a small footprint area of around 1 mm², a 21‐fold increase of the mass loading is achieved while featuring fast charge transfer at the nanoscale. The spiral microelectrode delivers a maximum area capacity of 1053 µAh cm^?2 with a retention of 67% over 50 cycles. Moreover, the energy density of the cylinder microbattery using the spiral microelectrode as the anode reaches 12.6 mWh cm^?3 at an ultrasmall volume of 3 mm³. In terms of the device volume and energy density, the cylinder microbattery outperforms most of the current microbattery technologies, and hence provides a new strategy to develop high‐performance microbatteries that can be integrated with miniaturized electronic devices.     

Thermal equation of state of natural chromium spinel up to 26.8 GPa and 628 K

A pressure–volume–temperature data set has been obtained for natural chromium spinel, using synchrotron X-ray diffraction with a resistance heated diamond-anvil cell (RHDAC). The unit cell parameter of the chromium spinel was measured by energy dispersive X-ray diffraction up to pressures of 26.8 GPa and temperatures of 628 K. No phase change has been observed. The observed P–V–T data were fit to the high-temperature Birch-Murnaghan equation of state, with V ₀ fixed at its experimental value, yields K ₀ = 209 ± 9 GPa, (∂K/∂T)_P = −0.056 ± 0.035 GPa K⁻¹, and α₀ = 7±1 × 10⁻⁵ K⁻¹. The temperature derivative of the bulk modulus (∂K/∂T)_P of chromium spinel is determined here for the first time. The obtained K ₀ is slightly higher than the previous results of synthetic spinel. We suggest that Fe²⁺–Mg²⁺ substitution is responsible for the high bulk modulus of chromium spinel.     

Effect of praseodymium substitution on the growth and properties of Y1−x Pr x Ba2Cu3O7−δ (o <x < 0·4) single crystals

In the present paper, a modified self-flux technique has been successfully employed for the growth of pure and praseodymium substituted (partially) large single crystals of high temperature superconducting Y_1−x Pr _x Ba₂Cu₃O_7−δ (x = 0·0,0·2,0·4). Typical sizes of the platy and bulky crystals of pure YBCO(123) material are ≈ 2 × 2 × 0·1 mm³ and 4 × 1 × 1 mm³, respectively. In case of Pr-substitution, the typical sizes of platy and bulky crystals of Y_0·8Pr_0·2Ba₂Cu₃O_7−δ and Y_0·6Pr_0·4Ba₂Cu₃O_7−δ materials are ≈ 2 × 3 × 0·1 mm³ and 5 × 1 × 1 mm³ and ≈ 1 × 1·5 × 0·1 mm³ and 7 × 0·2 × 0·1 mm³, respectively. The morphology and growth habit of the as-grown single crystals and the critical transition temperature (T _c) of the oxygenated crystals were found to depend on the Pr-content. Paper presented at the poster session of MRSI AGM VI, Kharagpur, 1995     

Preparation of high nickel-containing MCM-41-type mesoporous silica via a modified direct synthesis method

A method with modifying tetraethyl orthosilicate (TEOS) with nickel species has been developed for the synthesis of mesoporous silica with high nickel content (11.8 wt.% of Ni or even higher). With the method, MCM-41-type materials were obtained with high BET surface area reaching 868 m²/g and pore volume up to 0.73 cm³/g. The materials were characterized by means of X-ray powder diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy, N₂ adsorption, Fourier transform infrared and X-ray photoelectron spectroscopy. Nickel species were incorporated into the silica frameworks. The mesostructures still remain after activation using H₂ at 773 K.     

Structure, hardness and thermal stability of TiAlN and nanolayered TiAlN/CrN multilayer films

TiAlN films were deposited on silicon (1 1 1) substrates from a TiAl target using a reactive DC magnetron sputtering process in Ar+N₂ plasma. Films were prepared at various nitrogen flow rates and TiAl target compositions. Similarly, CrN films were prepared from the reactive sputtering of Cr target. Subsequently, nanolayered TiAlN/CrN multilayer films were deposited at various modulation wavelengths (Λ). X-ray diffraction (XRD), energy dispersive X-ray analysis, nanoindentation and atomic force microscopy were used to characterize the films. The XRD confirmed the formation of superlattice structure at low modulation wavelengths. The maximum hardness of TiAlN/CrN multilayers was 3900 kg/mm², whereas TiAlN and CrN films exhibited maximum hardnesses of 3850 and 1000 kg/mm², respectively. Thermal stability of TiAlN and TiAlN/CrN multilayer films was studied by heating the films in air in the temperature range (T_A) of 500-900 °C for 30 min. The XRD spectra revealed that TiAlN/CrN multilayers were stable up to 800 °C and got oxidized substantially at 900 °C. On the other hand, the TiAlN films were stable up to 700 °C and got completely oxidized at 800 °C. Nanoindentation measurements performed on the films after heat treatment showed that TiAlN retained a hardness of 2200 kg/mm² at T_A=700 °C and TiAlN/CrN multilayers retained hardness as high as 2600 kg/mm² upon annealing at 800° C.     

Phase instabilities during Ti-nitride precipitation in nitrogen implanted Ti-6AI-4V alloy

Grazing incidence X-ray diffraction, performed on a 70 keV nitrogen implanted Ti-6Al-4V system, reveals phase instabilities, during the course of nitride formation. With the build up of unbound N atom concentration, for a dose of 1×10¹⁶ ions/cm², the surface region becomesα-rich, whereas, on precipitation of Ti-nitrides at a high dose of 1×10¹⁷ ions/cm², theβ-Ti phase reappears, at the surface and beyond the implanted zone. The low concentration of V and the strain in the nitrided zone, have led to radiation induced martensitic transformation of theβ-Ti phase.     

Physical and chemical response of 70 MeV carbon ion irradiated Kapton-H polymer

Physical and chemical responses of 70 MeV carbon ion irradiated Kapton-H polymer were studied by using UV-visible, FTIR and XRD techniques. The ion fluences ranging from 9.3 × 10¹¹−9 × 10¹³ ions cm⁻² were used. Recorded UV-visible spectra clearly showed a decrease in absorption initially with fluence, but for the higher fluences it showed a recovery characteristic. A decrease in band-gap energy of 0.07 eV was observed. The FTIR analysis indicated the high resistance to radiation induced degradation of polymer. The diffraction pattern of Kapton-H indicates that this polymer is semi-crystalline in its nature. In case of irradiated one, there was an average increase of crystallite size by 20%, but diffuse pattern indicates that there was a decrease in crystallinity, which may be attributed to the formation of complex structure induced by the cross-linking of the polymeric chains.     

金属基复合材料残余应力测定

分析了金属基复合中热残余应力的形成机理及表现特点，并对几种常用的测定金属基复合材料残余应力的方法进行了分析比较，普通Ｘ射线法虽然简便、经济、但穿透能力有限，所测值仅反映试样表面的残余应力状态；中子衍射的区域较大，测出的仅是残余应力平均值。Ｘ射线能量衍射法虽然穿透能力较强，能测出试样内部较深范围的残余应力，但由于产生衍射法穿透力强，分辩率高，能测出复合材料内部的残余应力场梯度，是测定金属基复合材料残     

Coulometric thickness gauges and metrological assurance

The potentialities of the coulometric method of thickness measurement are analyzed. The design features and technical capabilities of the Limeda DEM microcoulometric thickness gauge are considered. The gauge can be used for measurements on a small area (1 mm²) with a rapid rate of electroetching (0.5 μm/sec). Methods and means of providing metrological assurance for the gauge are briefly outlined. Translated from Izmeritel'naya Tekhnika, No. 3, pp. 27–31, March, 1996.     

Measurement of absorbed dose by 7-GeV bremsstrahlung in a PMMA phantom

High-energy electron storage rings generate energetic bremsstrahlung photons through radiative interaction of the particle beam with the residual gas molecules and other components inside the storage ring. At synchrotron radiation facilities, where beamlines are channeled out of the storage ring, a continuous bremsstrahlung spectrum, with a maximum energy of the stored particle beam, will be present. At the advanced photon source (APS), where the stored beam energy is 7 GeV, bremsstrahlung generated in the straight sections of the insertion device beamlines, which are a total of 15.38 m in length, can be significant. The contribution from each bremsstrahlung interaction adds up to produce a narrow mono-directional bremsstrahlung beam that comes down through the insertion device beamlines. The resulting absorbed dose distributions by this radiation in a 300 mm×300 mm×300 mm tissue substitute cube phantom were measured with LiF:Mg,Ti (TLD-700) thermoluminescent dosemeters. The normalized absorbed dose, in a cross-sectional area of 100 mm² at a depth of 150 mm of the PMMA phantom, was measured as 3.3×10⁶ mGy h⁻¹W⁻¹ for 7-GeV bremsstrahlung spectrum.     

Some characteristics of electric explosion of zinc wires

Some physical characteristics necessary for calculating the circuit of and selecting the optimum conditions for the electric explosion of zinc wires have been experimentally determined, including the specific action of zinc h _b = (0.70 ± 0.15) × 10⁵ A² s/mm⁴ (for maximum current densities 2.5 × 10⁵ A/mm² < j _M < 4.5 × 10⁵ A/mm²) and the critical length of exploding wire λ_cr = 1.8 × 10³ (ɛν × 10⁻⁶)^0.56.     

Bidirectional Reflection Measurements of Periodically Microstructured Silicon Surfaces

Surface modifications have a great potential for selective emission and absorption for applications in photonics, energy conversion, and biosensing. Pattern-induced radiative property changes can be an important issue in the manufacturing and diagnostics of microelectronic devices. This work investigates the polarized diffraction of micromachined silicon wafers. Both one-dimensional (1-D) and two-dimensional (2-D) periodic microstructures are manufactured by plasma-assisted anisotropic etching. The rotating mask method is used to produce 2.25 × 10⁶ 2-D structures in a single sample (7.5 × 7.5 mm²). Surface topography is characterized by using a scanning electron microscope (SEM). A bidirectional scatterometer with high accuracy and angular resolution measures the diffraction patterns from the microstructured silicon surfaces at a wavelength of 635 nm. The diffraction patterns follow the grating equation, which are caused by microstructures and their orientations. Predicted diffraction angles are in excellent agreement with the experimental results.     

能量色散法在铁单晶应力测量中的应用

为了更精确地进行材料内部的应力测量，尝试了用能量色散法进行应力测量的模拟研究。模拟计算的结果分析表明：能量色散法进行应力测量的分辨率（3．9×10^-4）优于传统的应力测量方法的分辨率（101），并且在波长选定的情况下，狭缝的宽度与试样厚度是影响结果的主要因素。     

In-situ studies of the recrystallization process of CuInS2 thin films by energy dispersive X-ray diffraction

Recrystallization processes during the sulfurization of CuInS₂ (CIS) thin films have been studied in-situ using energy dispersive X-ray diffraction (EDXRD) with synchrotron radiation. In order to observe the recrystallization isolated from other reactions occurring during film growth, Cu-poor, small grained CIS layers covered with CuS on top were heated in a vacuum chamber equipped with windows for synchrotron radiation in order to analyze the grain growth mechanism within the CIS layer. In-situ monitoring of the grain size based on diffraction line profile analysis of the CIS-112 reflection was utilized to interrupt the recrystallization process at different points. Ex-situ studies by electron backscatter diffraction (EBSD) and energy dispersive X-ray spectroscopy (EDX) performed on samples of intermediate recrystallization states reveal that during the heat treatment Cu and In interdiffuse inside the layer indicating the importance of the mobility of these two elements during CuInS₂ grain growth.