离心铸造SiCp／A356功能梯度材料的组织结构与耐磨性

采用离心铸造法制备了ＳｉＣｐ／Ａ３５６功能梯度材料并研究了其组织结构及耐磨性。结果表明，离心铸造ＳｉＣｐ／Ａ３５６梯度材料组织致密，ＳｉＣ粒子在材料中呈梯度分布；在离心力场的作用下，消除了ＳｉＣ粒子团聚常来的缺陷，使ＳｉＣ粒子与合金基体紧密结合，充分发挥了ＳｉＣ粒子的优良性能，从而较大地提高了材料的耐磨性。     

退火Fe_（73．5）Cu_1Nb_3Si_（13．5）B_9合金中α－Fe（S

用ＸＲＤ法研究了退火Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９合金中α－Ｆｅ（Ｓｉ）晶化相的有序化过程．结果表明，Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９非晶合金在４９０℃，１ｈ退火后，α－Ｆｅ（Ｓｉ）晶化相是具有ＤＯ３结构的有序相，有序畴为球形，直径为７．０ｎｍ，它随退火温度的升高而长大，在５９０℃退火后达１０．９ｎｍ，与α－Ｆｅ（Ｓｉ）的尺寸相当．此时，α－Ｆｅ（Ｓｉ）的有序度为０．８在８５０℃，１ｈ退火后，α－Ｆｅ（Ｓｉ）的ＤＯ３超点阵线条消失．在５５０℃等温退火时，α－Ｆｅ（Ｓｉ）的ＤＯ３有序畴先为椭球状，于６０ｍｉｎ退火后形成球状，直径为１０ｎｍ．     

THE ORDERING OF THE α-Fe(Si)PHASE IN Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9 ANNEALED ALLOY

用ＸＲＤ法研究了退火Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９合金中α－Ｆｅ（Ｓｉ）晶化相的有序化过程，结果表明，Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９非晶合金在４９０℃，１ｈ退火后，α－Ｆｅ（Ｓｉ）晶化相是具有ＤＯ３结构的有序相，有序畴为球形，直径为７．０ｎｍ，它随退炎温度的升颃是长大，在５９０℃退火后达１０．９ｎｍ，与α－Ｆｅ（Ｓｉ）的尺寸相当，此时α－Ｆｅ（Ｓｉ）的有序度为０．８，在８５０℃     

Si及α—Al2O3超细粉对Al2O3—ZrO2—C系材料显微结构的影响

本文探讨了Ｓｉ及α－Ａｌ２Ｏ３超细粉对Ａｌ２Ｏ３－ＺｒＯ２－Ｃ系材料显微结构的影响。认为在Ａｌ２Ｏ３－ＺｒＯ２－Ｃ系材料中同时加入Ｓｉ和α－Ａｌ２Ｏ３超细粉，Ｓｉ粉除了与Ｃ生成了ＳｉＣ纤维外，其反应产物ＳｉＯ２还与α－Ａｌ２Ｏ３超细粉及ＺｒＯ２生成了莫来石（Ａ３Ｓ２）和Ａｌ２Ｏ３－ＺｒＯ２－ＳｉＯ２（ＡＺＳ）固溶体，这些新生成的矿物相对试样的显微结构产生重要的作用。     

Si及α－Al_2O_3超细粉对Al_2O_3－ZrO_2－C系材料显微结构的影

本文探讨了Ｓｉ及α－Ａｌ２Ｏ３超细粉对Ａｌ２Ｏ３－ＺｒＯ２－Ｃ系材料显微结构的影响．认为在Ａｌ２Ｏ３－ＺｒＯ２－Ｃ系材料中同时加入Ｓｉ和α－Ａｌ２Ｏ３超细粉，Ｓｉ粉除了与Ｃ生成了ＳｉＣ纤维外，其反应产物ＳｉＯ２还与α－Ａｌ２Ｏ３超细粉及ＺｒＯ２生成了莫来石（Ａ３Ｓ２）和Ａｌ２Ｏ３－ＺｒＯ２－ＳｉＯ２（ＡＺＳ）固溶体，这些新生成的矿物相对试样的显微结构产生重要的作用．     

Co薄膜的稳定性和室温相观察

用电镜对Ｓｉ（００１）基体上的Ｃｏ薄膜的室温相和稳定性进行了观察，高分辨像和小角解理的电子衍射结果均表明：室温下，Ｃｏ薄膜不发生反应，室温相为α－Ｃｏ，没有硅化物形成，Ｃｏ薄膜在经过３００℃２ｈ退火后，薄膜发生部分凝聚现象，凝固团由硅化物组成，３００℃退火后薄膜由Ｃｏ２Ｓｉ和ＣｏＳｉ两相组成。     

用正电子湮没技术研究退火温度对FeCuNbSiB合金微观缺陷的影响

利用正电子湮没技术结合Ｘ－射线衍射分析了Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９纳变软磁合金在不同退火温度下，微观缺陷与相应相结构和软磁性能的变化规律。     

预退火对Fe73.5Cu1Mo3Si13.5B9纳米晶合金形成的影响

采用Ｘ射线衍射，电子衍射及透射电子显微技术研究了Ｆｅ７３．５Ｃｕ１－ｘＭｏ３Ｓｉ１３．５Ｂ９非晶合金４１０℃预退火对随后４８０℃退火所形成的纳米晶结构的影响。结果表明，预退火对Ｆｅ７３。０５，Ｃｕ１Ｍｏ３Ｓｉ１３．５Ｂ９合金纳米晶结构的形成有重要影响。当预退火时间从０小时增加到３小时，合金在４８０℃，小时退火形成的晶相化α－Ｆｅ（Ｓｉ）的晶粒尺寸从１５ｎｍ减小到８ｎｍ。预退火使α－Ｆｅ（Ｓｉ）相的     

快中子辐照CZ-Si的FTIR分析

应用FTIR技术研究了不同剂量(1×1017～1.17×1019n/cm2)快中子辐照直拉硅(CZ-Si)的辐照缺陷和间隙氧在不同温度热处理时的行为.发现随辐照剂量的增加未退火的样品的间隙氧含量迅速下降,并且间隙氧的下降明显分为3个阶段.FTIR谱表明快中子辐照后主要的辐照缺陷为VO(829 cm-1)复合体.在低温条件下热处理300℃829cm-1(VO)开始消失并出现了825 cm-1(V2O2)、833cm-1(V3O2)、和840cm-1(V2O)和919cm-1(I2O2)四个红外吸收峰,退火温度升高到500℃后只剩下了825cm-1和919cm-1两个缺陷-杂质复合体的红外吸收峰.高温1100℃0.5h辐照引入的缺陷-杂质复合体很快的被消除.延长退火时间辐照样品和未辐照样品的间隙氧沉淀速度有很大的不同.     

ZG0Cr17Ni17Si5新型铸造不锈钢研制

对新型铸造不锈钢ＺＧ０Ｃｒ１７Ｎｉ１７Ｓｉ５进行了成分设计，研究了该钢的金相组织、腐蚀形貌和耐蚀性能，并试验了钢的力学性能、冶炼工艺、铸造性能与焊接性能。结果表明，ＺＧ０Ｃｒ１７Ｎｉ１７Ｓｉ５不锈钢具有优良的耐蚀性、较高的强度与良好的塑韧性并具有较好的冶炼、铸造和焊接性能，是一种综合性能好，成本低的优良不锈钢种。     

In-situ neutron radiography investigations of hydrogen diffusion and absorption in zirconium alloys

The fast and non-destructive character of neutron radiography provides the possibility of in-situ investigations of hydrogen uptake and diffusion in zirconium alloys. A special reaction furnace with neutron transparent windows was constructed. The method of quantitative hydrogen determination by neutron transmission measurements was calibrated for each experimental run. Additionally, oxygen is absorbed in the α-Zr phase and precipitated in the oxide layer. The calibration of the correlation between hydrogen and oxygen concentrations and total neutron cross-sections at room temperature and between 1123 and 1623 K are described.Results of in-situ neutron radiography investigations of hydrogen diffusion and absorption are presented in this paper. A linear dependence of the total macroscopic neutron cross section on the H/Zr atomic ratio as well as on the oxygen concentration was found. No significant temperature dependence of the total neutron cross-sections of hydrogen dissolved in β-Zr or oxygen dissolved in the α-Zr or precipitated in the oxide layer was found.     

Visualization of dynamic 3-D water behavior in polymer electrolyte fuel cell by using neutron image intensifier

Visualization of dynamic three-dimensional water behavior in a polymer electrolyte fuel cell (PEFC) stack was carried out by neutron CT using a neutron image intensifier. The neutron radiography system at JRR-3 in Japan Atomic Energy Agency was used. An operating stack with three cells based on Japan Automobile Research Institute standard was visualized. A consecutive CT reconstruction method by rotating the fuel stack continuously was developed using a neutron image intensifier and a C-MOS high speed video camera. The dynamic water behavior in channels in the operating PEFC stack was clearly visualized in 15 s intervals by the present dynamic neutron CT system.     

A physical model of the oxygen subsystem evolution in PLZT ceramics under neutron irradiation and annealing

A physical model describing the evolution of defects in the oxygen subsystem of ferroelectric PLZT ceramics under neutron irradiation and isochronous annealing conditions is proposed. The model takes into account the dependence of the material properties on the lanthanum content. The oxygen vacancy concentration variations calculated using this model agree with the experimental data on the polarization behavior in annealed ceramics.     

Light charged-particle production in 96 MeV neutron-induced reactions on carbon and oxygen

In recent years, an increasing number of applications involving fast neutrons have been developed or are under consideration, e.g. radiation treatment of cancer, neutron dosimetry at commercial aircraft altitudes, soft-error effects in computer memories, accelerator-driven transmutation of nuclear waste and energy production and determination of the response of neutron detectors. Data on light-ion production in light nuclei such as carbon, nitrogen and oxygen are particularly important in calculations of dose distributions in human tissue for radiation therapy at neutron beams, and for dosimetry of high-energy neutrons produced by high-energy cosmic radiation interacting with nuclei (nitrogen and oxygen) in the atmosphere. When studying neutron dose effects, it is especially important to consider carbon and oxygen, since they are, by weight, the most abundant elements in human tissue. Preliminary experimental double-differential cross sections of inclusive light-ion (p, d, t, (3)He and alpha) production in carbon induced by 96-MeV neutrons have been presented. Energy spectra were measured at eight laboratory angles: 20, 40, 60, 80, 100, 120, 140 and 160 degrees . Measurements were performed at The Svedberg Laboratory (TSL), Uppsala, using the dedicated MEDLEY experimental setup. The authors have earlier reported experimental double-differential cross sections of inclusive light-ion production in oxygen. In this paper, the deduced kerma coefficients for oxygen has been presented and compared with reaction model calculations.     

Reusable shielding material for neutron- and gamma-radiation

At neutron research facilities all around the world radiation shieldings are applied to reduce the background of neutron and gamma radiation as far as possible in order to perform high quality measurements and to fulfill the radiation protection requirements.The current approach with cement-based compounds has a number of shortcomings:“Heavy concrete” contains a high amount of elements, which are not desired to obtain a high attenuation of neutron and/or gamma radiation (e.g. calcium, carbon, oxygen, silicon and aluminum).A shielding material with a high density of desired nuclei such as iron, hydrogen and boron was developed for the redesign of the neutron radiography facility ANTARES at beam tube 4 (located at a cold neutron source) of FRM-II. The composition of the material was optimized by help of the Monte Carlo code MCNP5. With this shielding material a considerable higher attenuation of background radiation can be obtained compared to usual heavy concretes.     

Top-Seeded Melt-Growth of YBa2Cus3Ox Crystals for Neutron Diffraction Studies

We have grown cubic centimeter-size crystals of YBa₂Cu₃O _x suitable for neutron studies, by a top-seeded melt-growth technique. Growth conditions were optimized with an eye toward maximizing phase purity. It was found that the addition of 2% Y₂BaCuO₅ and 0.5% Pt (by mass) were required to prevent melt loss and to obtain the highest crystallinity. A neutron diffraction study on a mosaic of six such crystals found that the final Y₂BaCuO₅ concentration was 5%, while other impurity phases comprised less than 1% by volume. The oxygen content was set to x = 6.5, the crystals were detwinned, and then carefully annealed to give the well-ordered ortho-II phase. The neutron study determined that 70% of the mosaic's volume was in the majority orthorhomic domain. The neutron (006) and (110) rocking curve widths were ～1° per crystal and ～2.2° for the mosaic, and the oxygen chain correlation lengths were >100 Å in the a- and b-directions and ～50 Å in the c-direction.     

Pressure-induced formation of electrically active centres in irradiated silicon: comparison of electron and neutron irradiation

The effect of annealing at 300-500 °C under enhanced hydrostatic pressure (up to 1.2 GPa) in argon ambient on the interstitial oxygen aggregation (thermal donors) in Czochralski-grown silicon subjected to electron and neutron irradiation was investigated by infrared absorption and electrical techniques. Strong pressure- and irradiation-enhanced changes in oxygen concentration, formation of intrinsic p-n-junctions, conversion of conductivity type due to formation of the thermal donors and thermal acceptors were found. A comparison with neutron-irradiated samples is made.     

Calibration and testing of a TLD dosemeter for area monitoring

The response of a TLD-600/TLD-700 area dosemeter has been characterized in neutron fields around the 590 MeV cyclotron ring at the Paul Scherrer Institute (PSI). The dosemeter is based on a cylindrical paraffin moderator with three of each type of TLD chip at the centre, and is intended to use for area monitoring around accelerator facilities. The dosemeter is calibrated in terms of ambient dose equivalent using a non-moderated 252Cf neutron source. The ambient dose equivalent response has been tested in five locations where the neutron fields and dose rates have been well characterized by Bonner sphere spectrometer and active neutron monitor measurements. The different spectrum shapes and dose rates in the five locations permit the comparison of the behavior of the active and passive dosemeters in these neutron fields.     

Structural, magnetic and electrochemical characterization of La0.83A0.17Fe0.5Cr0.5O3−δ (A = Ba, Ca) perovskites

The structural, magnetic and electrical properties of the perovskite-type compound La_0.83A_0.17Fe_0.5Cr_0.5O_3−δ (A = Ba, Ca) have been investigated by neutron diffraction, magnetization measurements and conductivity measurements. Rietveld refinement of X-ray and neutron diffraction data shows that the compound adopts an orthorhombic crystal structure with Pbnm symmetry with a random positioning of the iron and chromium cations on the B sublattice. The magnetic structures at 10 K are collinear antiferromagnetic with the magnetic moment per site being equal to 2.91(2)μ_B (for Ba) and 3.05(2)μ_B (for Ca). Magnetization measurements confirm the overall antiferromagnetic behavior. The magnetic structure is based on a unit cell related to that of the nuclear structure and the magnetic cell can be considered the same as nuclear cell. Barium doped samples show lower oxygen deficiency and higher conductivity than calcium doped samples. At low oxygen pressure, both compounds show p-type electronic conduction.     

A history of basic neutron radiography research at Rikkyo University

A study of neutron imaging was initiated by a research group in our institute using the 100 kW Rikkyo TRIGA reactor, in 1984. A series of studies at the Rikkyo University was reported in the proceedings of these conferences and others and were covered mainly in the field of neutron beam qualification methods, analysis of image qualification, new imaging methods, and analysis of neutron behavior in materials. In this paper, a history of these principal studies will be summarized and a few unresolved basic studies will also be mentioned.