Fe_（73．5）Cu_1Nb_3Si_（13．5）B_9非晶合金化过程的X射线

采用Ｘ射线衍射和正电子湮没多普勒展宽测量相结合，研究了纳米晶态材料Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９的结构随退火温度的变化。实验结果表明：急冷非品样品在４８０℃开始明显晶化，基体中析出体心立方结构的α－Ｆｅ（Ｓｉ）固溶体。随着退火温度的升高，非晶漫射峰不断减弱，而晶态相的衍射谱逐渐增强。进一步计算对衍射谱的分离，给出了品化分数和非晶相平均原子间距随退火温度的变化规律。正电子湮没实验证实了约５５０℃退火时样品内出现以Ｎｂ、Ｂ原子为主的晶界非晶相，Ｓ参数随退火温度的变化与非晶相平均原子间距随退火温度的变化规律一致。     

Fe73.5Cu1Nb3Si13.5B9非晶合金化过程的X射线衍射和正电子湮没研究

采用Ｘ射线衍射和正电子湮没多普勒展宽测量相结合，研究了纳米晶态材料Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９的结构随退火温度的变化。实验结果表明：急冷非晶样品在４８０℃开始明显晶化，基体中析出体心立方结构的α－Ｆｅ（Ｓｉ）固溶体。随着退火温度的高，非晶漫峰不断减弱，而晶态相的衍射谱逐渐增强。进一步计算对衍射谱的分离，给出了晶化分数和非晶相平均原子间距随退火温度的变化规律。正电子湮没实验证实了约５５０     

非晶合金Fe73.1Cu1.2Nb3.2Si12.5B10.0晶化的Mossbauer研究

采用Ｍｏｓｓｂａｕｅｒ效应和ＸＲＤ分析方法研究了非晶合金Ｆｅ７３．１Ｃｕ１．２Ｎｂ３．２Ｓｉ１２．５Ｂ１０．０的晶化。实验表明，该非晶合金有两个晶化阶段。在第一阶段晶化后，样品主要由ＤＯ３型的α－ＦｅＳｉ合金的超细颗粒和作为晶界的非晶相两部分组成。随着退火温度的上升，晶化相的含量增加，非晶相含量减少。在第二阶段晶化后，残余的非晶相就晶化为Ｆｅ２Ｂ和Ｆｅ２３Ｂ６化合物以及可能为Ｆｅ－Ｎｂ－Ｂ之类的顺     

非晶合金Fe_（73．1）Cu_（1．2）Nb_（3．2）Si_（12．5）B_

采用Ｍ　ｓｓｂａｕｅｒ效应和ＸＲＤ分析方法研究了非晶合金Ｆｅ７３．１Ｃｕ３．２Ｎｂ３．２Ｓｉ１２．５Ｂ１０．０的晶化。实验表明，该非晶合金有两个晶化阶段。在第一阶段晶化后，样品主要由ＤＯ３型的ａ—ＦｅＳｉ合金的超细颗粒和作为晶界的非晶相两部分组成。随着退火温度的上升，晶化相的含量增加，非晶相含量减少、在第二阶段晶化后，残余的非晶相就晶化为Ｆｅ２Ｂ和Ｆｅ２３Ｂ６化合物以及可能为Ｆｅ－Ｎｂ－Ｂ之类的顺磁相。     

Fe—B超细微晶合金的正电子湮没研究

用正电子湮没技术对急地制备了Ｆｅ－Ｂ合金结晶态超细微粒（ＣＵＦＰ）的微结构进行了分析，寿命谱研究结果与正电子三态湮没模型相吻合，研究了Ｆｅ－Ｂ－ＣＵＦＰ的结晶与非晶两种结构的微缺陷，并推测Ｆｅ－Ｂ－ＣＵＦＰ聚集体（纳米晶膜）材料具有类原子气态微结构的可能性。     

掺Pb超导体（Bi2—xPbx）Ca2.5Nd0.5Cu2O8＋y的正电子寿命研究

室温测量了（Ｂｉ２－ｘＰｂｘ）Ｃａ２．５Ｎｄ０．５Ｃｕ２Ｏ８＋ｙ超导体的正电子寿命与Ｐｂ含量的关系。在２２１２相发现随着Ｐｄ含量的增加正电子体寿命相应地减小，分析表明，这是由于Ｐｂ替换了Ｂｉ，使电子从Ｃｕ－Ｏ面或其它晶位迁移到Ｂｉ－Ｏ层，并导致Ｂｉ－Ｏ层电子密度增加所致。     

YBa2Cu3—xSnxOy超导体系的正电子寿命谱研究

研究了Ｓｎ作Ｃｕ位元素替代的ＹＢａ２Ｃｕ３－ｘＳｎｘＯｙ超导体系（ｘ＝０－１．５）的正电子寿命谱，计算了局域电子密度和缺陷浓度的变化，发现了存在于高浓度替代区域（ｘ＝０．８－１．０）的正电子湮没特征，讨论了对超导电性的影响以及相应的物理机制。     

中子辐照硅的正电子湮没研究

采用正电子湮没方法研究了１．４５×１０＾２０ｎ／ｃｍ＾２和３．１０×１０＾１７ｎ／ｃｍ＾２快中子辐照高纯单晶硅的辐射损伤及其退火效应。在３４３－１０７３Ｋ温度范围内测量了正电子湮没寿命随退火温度的变化。实验观察到氧－空位对和在高中子剂量辐照的Ｓｉ中发现的双空位复合成四空位。正电子湮没短寿命成分τ１是晶格正电子寿命和氧－空位对捕获的正电子寿命的加权平均值，而长寿命成分τ２是双空位或四空位捕获的正电子     

YBa_2Cu_（3－x）Sn_xO_y超导体系的正电子寿命谱研究

研究了Ｓｎ作Ｃｕ位元素替代的ＹＢａ２Ｃｕ３－ｘＳｎｘＯｙ超导体系（ｘ＝０－１．５）的正电子寿命谱，计算了局域电子密度和缺陷浓度的变化；发现了存在于高浓度替代区域（ｘ＝０．８－１．０）的正电子湮没特征；讨论了对超导电性的影响以及相应的物理机制。     

掺杂BaTiO3系PTC材料的正电子湮没研究

采用正电子湮没寿命谱学的方法研究了ＢＳＴｉＯ３系ＰＴＣ材料中掺Ｎｂ５＋、Ｙ３＋及不同掺杂量所引起的缺陷变化，并讨论了不同掺杂对ＰＴＣ效应的影响。     

M"ossbauer study of the effect of Nb in Fe-based nanocrystalline alloy

Microstructure of nanocrystalline alloys of Fe73.5Cu1Nb3Si13.5B9and (Fe3Si)0.95Nb0.05 was investigated by M"ossbauerspectroscopy. A Nb-rich interfaciallayer with weak magnetism formed in the residual amorphous phase of these materials.It has an important effect on the exchange coupling and magnetic properties.     

Mssbauer study of the orientation of the magnetic moments in Fe-based nanocrystalline alloys

ＭｓｂａｕｅｒｓｔｕｄｙｏｆｔｈｅｏｒｉｅｎｔａｔｉｏｎｏｆｔｈｅｍａｇｎｅｔｉｃｍｏｍｅｎｔｓｉｎＦｅｂａｓｅｄｎａｎｏｃｒｙｓｔａｌｉｎｅａｌｏｙｓＨｕＢｉｎｇＹｕａｎ１，ＹａｎｇＪｉｅＸｉｎ１，ＣｈｅｎＧｕｏ１，ＳｈｅｎＧｕｏＴｕ１Ｊ...     

新型微晶软磁合金Fe_(73.1)Cu_(1.2)Nb_(3.2)Si_(12.5)B_(10)显微组织的穆斯堡尔研究

运用穆斯堡尔效应的方法考查了原始制备态和退火态的Fe_(73.1)Cu_(1.2)Nb_(3.2)Si_(12.5)B_(10)合金的显微组织。计算表明:退火的具有超细晶粒的微晶合金的显微组织主要由主晶相Fe_(75+y)Si_(25-y)型有序相和非晶态晶界相组成,可能含有很少量的顺磁相。组织中主相Fe_(75+y)Si_(25-y)含量大约为70％,非晶相约为26％。有序相Fe_(75+y)Si_(25-y)中的y在5—7之间。     

Hardening and microstructural evolution in A533B steels under high-dose electron irradiation

Commercial A533B steels (0.12, 0.16 wt% Cu) irradiated at 290 °C up to 22 mdpa with 5 MeV electrons were examined by hardness measurements, positron lifetime spectroscopy, the coincidence Doppler broadening (CDB) technique and three-dimensional atom probe microanalysis (3DAP). The radiation-induced hardening increased with electron dose and lay on the same trend of neutron-induced hardening within data scatter. CDB measurements revealed that clustering of Cu atoms occurred at doses over 1 mdpa and proceeded with increasing dose. 3DAP results showed that well-defined Cu-rich precipitates with a diameter of less than 2 nm were formed at doses of 10 and 22 mdpa. The precipitates had a shell structure consisting of a Cu–Fe core region and a surrounding Mn–Ni–Si shell, which are similar to those formed under neutron irradiation. The size and number density of the precipitates were consistent with previous neutron data. Positron lifetime spectroscopy showed that no microvoids were formed. The electron irradiation caused almost the same hardening efficiency and evolution of Cu-rich precipitates as those under neutron irradiation on a dpa basis.     

Corrosion behavior of Zr alloys with a high Nb content

The corrosion behavior of the Zr alloy with a high Nb content was evaluated in the water loop system containing 2.2 wppm Li and 650 wppm B. The characteristics of the precipitates were analyzed by transmission electron microscopy (TEM) and the oxide was characterized by an X-ray diffraction method using a synchrotron radiation source. On the basis of the results obtained by these measurements, the relationship among the oxidation behavior, the precipitate characteristics and the oxide properties was discussed. It was shown that the Cu addition was of benefit to the corrosion resistance of the Zr alloy with a high Nb content and the corrosion resistance of the Cu-containing alloy (Zr–1.5Nb–0.5Sn–0.2Fe–0.1Cu) was superior to that of the Cr-containing alloy (Zr–1.5Nb–0.5Sn–0.2Fe–0.1Cr). The fine β-Nb precipitates were found more frequently in the Cu-containing alloy than the Cr-containing alloy when heat-treated in the same condition. The fraction of the tetragonal zirconia in the region of the metal/oxide interface was higher in the Cu-containing alloy than the Cr-containing alloy, suggesting that the stabilization of the tetragonal phase in the oxide was promoted more when the smaller precipitates are incorporated into the oxide. It is concluded that the fine distribution of β-Nb is desirable for stabilizing the tetragonal phase in the oxide, thereby increasing the corrosion resistance of the Zr alloy with a high Nb content.     

Development of Nb tube processed Nb3Al multifilamentary superconductor

The Nb tube process has recently been developed at NRIM (Japan) for fabricating Nb₃Al multifilamentary superconductors containing more than one million continuous ultrafine filaments of less than 0.1 m diameter. The adjustment of hardness of Al cores relative to Nb matrix by alloying Al cores with additives of Mg, Ag(-Ge), Cu(-Ge), Zn, etc. improved remarkably the cold workability of Nb/Al composites. Wires heat treated below 1000°C show superior properties to a commercial multifilamentary (Nb,Ti)₃Sn conductor: (1) higherJ _c (4.2 K) (1.5×10⁹ A/m² at 10 T), (2) smaller degradation inJ _c with mechanical strain, and (3) smaller ac loss (resulting from a smaller effective superconducting filament diameter: about 2 m). Furthermore, sensitivity to irradiation is nearly the same as that of (Nb,Ti)₃Sn. Other techniques to produce Nb₃Al are unsuitable for developing a conductor with multifilamentary structure, and thereby the Nb tube processed Nb₃Al multifilamentary conductors is the best available for fusion reactor magnets.     

Measurements of hydrogen permeation and absorption in zirconium oxide scales

The hydrogen absorption and the permeation behavior through the oxide layer formed on modified Zircaloy-4 (Zry-4) alloys were investigated. The modified Zry-4 was prepared by altering the chemical composition of standard Zry-4. The tin content of Zry-4 (1.5 wt%) was reduced to 0.5 wt%, and alloying elements Si, O and Nb were added from 0.01 to 0.2 wt%. The oxide layers were grown in a static autoclave at 360 °C under 18.3 MPa for 150 days. Fick’s law was used to calculate the diffusivity of hydrogen after the steady state of the permeation flux was reached. The diffusivity of hydrogen in the 0.5Sn–0.1Nb–0.1Fe–0.2Cr–0.2O–Zr specimen was lower than that in the 1.5Sn–0.2Fe–0.1Cr–0.1O–0.01Si–Zr and Zry-4 specimens. As the area fraction of precipitates increased, the hydrogen diffusivity increased whereas an inverse relationship between the diffusivity and the amount of the tetragonal phase was observed. In addition to the oxide structural study, the effects of the microstructure of the zirconium alloys such as precipitates and grain boundaries on the hydrogen absorption were studied.     

Ar离子辐照的非晶态合金表面发泡扫描电镜观测

１５０、１９５和３００ｋｅＶＡｒ离子在室温下辐照非晶态合金Ｃｏ７０．２Ｆｅ３． ９Ｎｄ３．９Ｓｉ１４Ｂ８和Ｃｏ６６Ｆｅ４．５Ｖ２．２５Ｎｉ２．２５Ｓｉ１０Ｂ１５，扫描电镜在一定的辐照剂量范围观测到了表面发泡形成，发泡形成的临界剂量和直径随离能量增加而增加。Ａｒ离子能量高于１９５ｋｅＶ时，发泡和发泡破裂是主要的表面损伤现象，而在１５０ｋｅＶＡｒ离子辐照下，未观测到发泡破裂。