热轧温度对N18新锆合金板材织构的影响

研究了N18新锆合金在α／(α β)相变点附近不同热轧温度对板材织构的影响：结果表明,N18合金板材经热轧、冷轧及再结晶退火加工后．fn和fr增加,ft减小。热轧温度对织构的影响较小。热轧温度高于780℃的几块板材的织构基本一致;与热轧温度为750℃的板材相比,fn减小,ft略有增加。温度高于780℃。N18合金中出现β相,并且β相含量随温度升高而增加,750℃时热轧N18合金的形变遵循α相(hcp)的形变机制;780℃至820℃热轧,合金的织构仍由α相的变形所控制．除了锥面滑移和柱面滑移开外,还伴随高温形变机制,晶界分布的β相对晶界滑动机制有促进作用。     

含氢N18锆合金循环变形后的位错组态研究

应用透射电子显微镜研究了N18锆合金在室温下循环变形后的位错组态以及氢化物与位错的相互作用.结果表明,N18锆合金基体中存在着大量弥散分布的沉淀相粒子,其位错组态是一系列被沉淀相粒子钉扎住的位错线段.这些位错线段由{1010}柱面滑移所产生.试样在变形过程中只有部分晶粒发生了塑性变形,而其它晶粒则是弹性变形.试样中的氢化物主要为面心立方结构的δ相氢化锆,氢化物与位错之间的交互作用存在着"尺寸效应",位错的滑移能够切割过细小的氢化物,但不能穿越粗大的氢化物.     

再加工对改进型N18板材第二相的影响

采用差热分析(DSC)、扫描电镜(SEM)和透射电镜(TEM)等多种研究手段系统地研究了改进型N18板材再加工(在750℃、780℃和800℃热轧3或4道次后再冷轧,冷轧后在540~600℃退火1.5~50 h)对第二相的影响。结果表明:热轧进入了双相区。在冷轧和随后的退火过程中,热轧过程中形成的β-Zr发生分解,析出细小的第二相,导致团簇状分布的细小第二相的形成;第二相为密排六方(HCP)的Zr(Fe,Cr,Nb)_2相。原板材中大部分第二相的合金元素原子百分比n(Fe)/[n(Cr)+n(Nb)]在5/3附近。再加工之后,n(Fe)/[n(Cr)+n(Nb)]呈现下降的趋势。团簇析出的细小第二相中Nb含量更高,n(Fe)/[n(Cr)+n(Nb)]接近1。     

用正电子湮灭研究SmCo_5永磁体室温至740℃的组织变化

SmCo_5永磁合金是一种用途广泛的永磁材料,其居里点约为740℃。为找出材料在400℃以上性能变坏的原因,尝试进行了室温至740℃温度范围内等时(2小时)退火处理的SmCo_5合金的正电子湮灭研究。结果发现,材料中明显地存在着沉淀相的析出。作者认为,至少不能排除这一过程作为影响磁性的重要原因。 正电子平均湮灭率λ_(ap)能反映材料的基体性质。它的倒数称为材料的基体正电子寿命τb,     

Ni-W合金基带的织构

Ni-W合金是制备YBa₂Cu₃O_7-δ高温超导线（带）材的优良基带材料，对Ni-W基带要求是具有强的立方织构{100}<001>。本文采用放电等离子体烧结方法制备了Ni-W（%）合金，利用轧制辅助双轴织构基带技术（RABiTS）制备了Ni-W合金基带。利用X射线衍射方法研究了基带冷轧织构与W含量的关系，系统地研究了Ni-5%W基带的再结晶织构。研究结果表明：Ni-5%W基带是一个比较好的组分，通过大的冷轧形变量、较高的退火温度和两步退火的方式，有利于在Ni-5%W基带中形成单一的、强的立方织构。     

α+β两相区热处理对Zr-Sn-Nb合金微观组织和腐蚀性能的影响

对Zr-Sn-Nb合金在α+β两相区温度下不同工艺热处理后所得样品,在360 ℃/18.6 MPa纯水环境中进行均匀腐蚀试验,并采用扫描电子显微镜（SEM）观察样品微观形貌、聚焦离子束（FIB）和原子力显微镜（AFM）分析腐蚀后样品表面氧化膜。结果表明,Zr-Sn-Nb合金在α+β两相区温度下热处理时,锆合金中会形成条带状β-Zr第二相,再经过α相区温度最终退火后,β-Zr区域会分解为α-Zr和第二相粒子;经α相区最终退火的样品,在360 ℃/18.6 MPa纯水中的耐腐蚀性能优于未经最终退火的样品;未退火样品中条带状β-Zr第二相区域的氧化膜较α-Zr基体的氧化膜厚,而经过α相区温度退火后β-Zr发生分解,该区域的腐蚀氧化膜出现凹陷。     

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。     

退火处理对Ti—Al—Zr合金拉伸性能和腐蚀行为的影响

评估了退火对Ti-Al-Zr合金拉伸性能和腐蚀行为的影响。在500－800℃的温度范围内退火1小时，使得晶粒和沉淀相粒子尺寸增加。室温拉伸的结果表明，退火温度对强度和塑性几乎没有影响。然而在360℃，pH为9.98的氨水溶液中的腐蚀试验结果表明，抗腐蚀能力与退火温度有关，腐蚀速率随着退火温度的提高而增加。在220天的腐蚀试验期间所吸收的氢含量也随退火温度而增加。这可以归因于富铁沉淀相因退火而长大。建议采用较低的退火温度来得到良好的腐蚀性能，同时使室温拉伸性能下降。     

Nb-1Zr与316L不锈钢爆炸焊高温退火扩散层的显微组织分析

研究了Nb-1Zr合金与316L不锈钢爆炸焊在1 300 ℃退火后形成的互扩散层.该互扩散层宽度约为80 μm.用透射电子显微镜(TEM)分析观测到该扩散层中有大量针状析出相产生.经选区电子衍射(SADP)技术测定,析出相为亚稳定的ζ-(Nb, Ni)相,基体相为(Ni,Cr,Nb,C)Fe-α合金.     

热处理对锆-4合金中第二相结构和成分的影响(英文)

用电化学方法分离出锆-4合金中第二相,研究了不同热处理制度对第二相结构和成分的影响。锆-4合金经1050℃β相加热空冷后,析出的第二相为立方结构的Zr(Fe,Cr)_2,Fe/Cr比值在2.1～2.5之间。试样重新在600～800℃下加热3h,晶体结构不发生改变,只是Fe/Cr比值逐渐降至1.9;但在700～800℃下加热后,有少量的六方结构Zr(Fe,Cr)_2第二相析出。生产厂提供的锆-4板中第二相是六方结构的Zr(Fe,Cr)_2,重新在700～800℃加热3h,晶体结构不发生变化,Fe/Cr比值由1.9降至1.5左右。这说明在重新加热时,第二相中的Fe和Cr与周围基体中的Fe和Cr会相互扩散置换。试样从β相冷却析出第二相时,Fe原子的扩散比Cr原子快;Cr原子在六方晶格Zr(Fe,Cr)_2中的固溶度比在立方晶格Zr(Fe,Cr)_2中的大。由于这些原因造成了第二相成分随热处理制度不同而变化的现象。     

Preparation of Zn/TiO2 powder and its photocatalytic performance for oxidation of P-nitrophenol

Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn （11）. When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

The control system for SSRF injection and extraction

This paper introduces the injection and extraction control system design for SSRF,which is a distributed control system aimed at stability and reliability of the pulse power supplies,PPS(Personnel Protection System)and MPS(Machine Protection System).The hardware environment is mainly based on PLC(Programmable Logic Con- troller),and ARM(Advanced RISC Machine)is also applied for studying stability of the power supplies.WinCC and EPICS(Experimental Physics and Industrial Control System)have been selected as the platforms of SCADA(Super- visory Control and Data Acquisition).For unifying the interfacing to the control computer,all front-end equipments are connected via Industrial Ethemet.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

Investigations on landmine detection by BF3 detector

Experiments were carried out to investigate the possible use of neutron backscattering for the detection of polyethylene (PE) sample buried in the soil. In detection of landmine by neutrons, the neutron detector and its shield play an important role. In this paper, the effects of graphite, heavy water, polyethylene and boric acid moderators on the flux of back scattered neutrons were investigated. We have also experimentally verified the effect of BF3 detector shield and obtained good agreement with theory.     

Web Services interface of SSRF archive data analysis system

Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described.     

有效探测面积大于1000 cm2的正比计数器测量系统性能测试

为对自制的活性面积高达1 000 cm²的大面积源进行表面发射率定值,同时作为现有2πα、2πβ表面发射率标准装置能力的扩充,研制了一套内置式大面积2π多丝正比计数器测量系统,并利用活性区直径为8 mm的²⁴¹Am点源及活性区面积为10 cm×15 cm的大面积²⁴¹Am和⁹⁰Sr-⁹⁰Y源对其进行计量学性能测试。结果表明：计数器内计数响应均匀性优于±0.4%,有效探测面积达1 400 cm²;所得²⁴¹Am源高压坪曲线的坪长为1 400 V,坪斜为0.27%/100 V,坪区内计数变化为0.87%;⁹⁰Sr-⁹⁰Y源高压坪曲线的坪长为300 V,坪斜为0.75%/100 V,坪区内计数变化为0.80%;10次测量重复性好于0.4%,8 h内短期稳定性好于0.3%,1 a内长期稳定性好于0.8%。     

Assessment of radioactivity levels in some oil samples from the western desert, Egypt

Distributions of natural gamma-emitting radionuclides were determined in 93 oil samples collected from some petroleum fields in the western desert of Egypt. The radioisotope activities in the area under investigation lay in the range of (21 ± 4) to (38 ± 13) Bq?L-1 for 226Ra, (9 ± 2) to (15 ± 5) Bq?L-1 for 232Th, and (154 ± 28) to (303 ± 54) Bq?L-1 for 40K. The mean values were 27, 12, and 201 Bq?L-1, respectively. Among oils, variations in radionuclide ac- tivities could be on account of differences in TDS, HCO3, and Ba, with high or low pH. In this environment, oil prop- erties differently affected the mobilization of natural radionuclides. The range of 226Ra variation had been compared with available data from other countries. The calculated absorbed dose rate ranged from 22.33 to 32.66 nGy?h-1 in lo- cation (B) and (E) respectively, which was less than the accepted value.     

Preparation and properties of 117m Sn(IV)-TTHMP in in-vitro and in small animals

In this work,TTHMP was synthesized and labelled with 117m Sn.The preparation conditions,stability and lipophilicity of 117m Sn(IV)-TTHMP were investigated.Biodistribution of the complex in rabbits and mice was studied.It was found that the quantity of TTHMP and pH value of the prepararion solution had vital effects on the labeling yield of 117m Sn(IV)-TTHMP.It was also found that 117m Sn(IV)-TTHMP was hydrophilic and stable at room temperature and 37℃ in open air 117m Sn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals.This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.     

The role of AGFA high-energy CR in the calibration and quality control of multileaf collimators （MLC）

Linear accelerators equipped with multileaf collimators （MLC） are becoming more common and are widely used in the intensity-modulated radiotherapy （IMRT）. There is an imperative need to ensure the commissioning specification of the linear accelerators for the sake of quality assurance （QA） and quality control （QC）. This paper is aimed to investigate the role of AGFA high-energy CR （Computed Radiography） in calibrating dynamic multileaf collimators and evaluating the accuracy of the leaf position. The result shows that AGFA high-energy CR can easily and conveniently be used to calibrate MLC and verify its position. Hence, the application of AGFA high-energy CR is proved to be an accurate and time-saving method for routine MLC QC, especially when MLC calibration adjustments are required.