添加纳米Y2O3的ODS-HT9钢的显微结构和性能

为了研究纳米Y₂O₃对HT9钢的显微结构和力学性能的影响，采用粉末冶金工艺，制备了纳米Y₂O₃含量为0.1%~0.9%的ODS-HT9钢样品，测定了样品的抗拉强度、伸长率、维氏硬度等力学性能，利用透射电子显微镜（TEM）观察和分析了样品中纳米Y₂O₃颗粒的分布状况、形状和相结构，利用扫描电子显镜（SEM）观察了样品拉伸断口的形貌。研究表明，球磨和热压烧结后，纳米Y₂O₃颗粒能够均匀地分布于基体中，相结构和形状未发生明显变化。弥散分布的纳米Y₂O₃硬质颗粒，具有明显的弥散强化作用，导致ODS-HT9钢的抗拉强度和维氏硬度随Y₂O₃含量的增加而显著增加，伸长率显著降低。Y₂O₃含量低于0.7%时，样品以韧性断裂为主，进一步增加含量，断裂方式将由韧性断裂转变成脆性断裂。纳米Y₂O₃含量为0.3%~0.5%的ODS-HT9钢，抗拉强度达到了913~936 MPa，伸长率为10.7%~11.2%，具有良好的综合力学性能。本文研究结果有助于ODS-HT9钢高温性能的研究及其在反应堆中的实际应用。      

B4C-Al中子吸收材料拉伸性能及断裂机理

为评价粉末冶金法制备的B₄C-Al中子吸收材料的力学性能,采用静态拉伸的试验方法研究板材的室温及高温拉伸性能,并运用扫描电镜进行断口形貌观察,对复合材料的断裂机理进行讨论。研究表明：室温下,B₄C质量分数为30%的B₄C-Al复合板材的屈服强度为200 MPa,抗拉强度为250 MPa,断后伸长率为2.5%;在实验范围内,随着温度的升高,材料的抗拉强度和屈服强度下降,并趋于一致,材料的断后伸长率增加并达到最大值。复合材料的断裂宏观表现为脆性断裂,断裂是由基体内微孔隙成核、聚集和基体与增强相的界面脱粘断裂的共同作用造成的。     

氧化物弥散强化低活化合金的微观组织及力学性能

为了强化低活化合金(CLF-1)的高温性能,将采用Ar气超声雾化方法制备的CLF-1粉末与纳米Y₂O₃粉末混合后,经高能球磨和热等静压处理,获得氧化物弥散强化（ODS）CLF-1样品。对样品进行不同制度的热处理,并进行了微观组织分析和力学性能测试。分析结果表明,经过正火和回火处理,ODS CLF-1组织为回火马氏体,当正火温度为1 100 ℃时晶粒尺寸最为均匀。回火温度对显微组织影响不明显,但回火温度升高,维氏硬度下降。热处理后样品中观察到明显的弥散分布的Y₂O₃颗粒和位错塞积,证实了弥散强化的作用。Y₂O₃颗粒尺寸不均匀,100 nm左右的大颗粒倾向于沿晶界分布,而较小的颗粒则在晶内分布。ODS CLF-1样品具有良好的高温拉伸性能,600 ℃时抗拉强度为370 MPa,延伸率为18.5%。屈服强度和抗拉强度随热处理温度的升高而降低。     

不锈钢/碳钢爆炸复合板消除应力热处理(英文)

为了消除爆炸焊接不锈钢/碳钢复合板界面的残余应力,对实验样品进行了消除应力热处理,并做了力学性能测试、显微硬度测量、扫描电镜分析和金相分析。结果表明,不论是否经过热处理,界面两侧的成分都有互相扩散发生;热处理温度小于550℃时,力学性能、金相组织和显微硬度变化不大;热处理温度高于650℃,硬度曲线下降到接近原材的硬度,但同时界面近区碳钢表层发生脱碳现象;热处理温度在750℃时,碳钢内部还发生相变。因此不锈钢/碳钢复合板的最佳热处理温度可能在600℃左右。     

钼合金基体等离子喷涂Al_2O_3涂层研究

本工作研究了钼合金作为基体等离子喷涂Al2O3的喷涂工艺,并对喷涂样品进行了分析。其中,基体材料钼合金的尺寸为φ26mm×10mm,涂层材料为99%的高纯Al2O3粉末,粒度为10～30μm。试样端面喷砂活化处理之后进行等离子喷涂。试验采用有底层和无底层两种喷涂方式,涂层厚度为0.25mm。分别对涂层的金相组织、孔隙率、硬度和结合强度进行测试。结果表明,有底层涂层样品的结合强度为5MPa左右,无底层的结合强度为17MPa,观察到底层与基体结合处产生裂纹导致强度偏小。Al2O3涂层的孔隙率随着喷涂距离的增大而增大,显微硬度和结合强度相反则随着喷距…     

重复焊接对304不锈钢热影响区组织与性能的影响

采用自动钨极氩弧焊接（GTAW）工艺设计刚性约束坡口,制备了304不锈钢1次焊接和1~5次试样。采用光学显微镜、X射线衍射（XRD）、扫描电子显微镜（SEM）与电子背散射衍射（EBSD）技术对重复焊接试样的热影响区（HAZ）显微组织进行观察分析,并开展室温拉伸性能测试,研究重复焊接对显微组织与力学性能的影响。结果表明,重复焊接试样的HAZ显微组织主要由奥氏体和条状δ铁素体组成,随着重复焊接次数增加,HAZ奥氏体晶粒尺寸呈长大趋势,δ铁素体含量先减少后增加,组织择优取向由<101>转变为<111>,局域取向差逐渐增大;晶粒尺寸是影响抗拉强度和延伸率变化的主要原因,加工硬化致使试样屈服强度逐渐增加。      

316LN奥氏体不锈钢焊缝低温热老化行为研究

在压水堆核电厂中,主管道奥氏体不锈钢焊缝长期在其热老化敏感温度(280~325℃)下运行,为了研究主管道奥氏体不锈钢焊缝在核电厂运行温度下的热老化性能,开展了铁素体含量为10.7%的316LN不锈钢主管道焊缝在325、365、400℃下的低温热老化行为研究。结果表明:经6000 h热老化后,焊缝中铁素体相和奥氏体相中的主要元素含量没有发生明显变化,焊缝显微硬度快速增加但奥氏体相显微硬度没有发生变化,焊缝冲击功显著下降、拉伸性能变化较小。     

聚变堆第一壁TiC涂层材料研究(英文)

介绍了TiC涂层的化学气相沉积工艺,TiC涂层材料的电子束热冲击实验和热疲劳试验。在温度为1100℃,CH_4流量为0.36L/min,H_2流量为1.16L/min的工艺条件下,得到了致密的TiC涂层,且沉积速率达0.7/μm/min,并给出了涂层厚度与工艺参数之间的经验关系式。在高功率密度(最大值达226MW/m~2,作用0.6s)电子束热冲击下,TiC涂层从基体(石墨、钼、316L不锈钢)脱落,且316L不锈钢基体被熔化、蒸发。在900℃到-246℃之间的热循环实验下,TiC/316L不锈钢表现出极差的抗疲劳特性,仅在2次热循环之后,就有大量TiC涂层从316L不锈钢基体脱落;虽然TiC/石墨的涂层中有大量网状裂纹形成,但是,在200次热循环之后,TiC涂层与基体仍结合很好;TiC/钼有很好的抗疲劳特性,在200次热循环之后,材料仍没有任何损伤。     

聚变堆第一壁TiC涂层材料研究

介绍了TiC涂层的化学气相沉积工艺,TiC涂层材料的电子束热冲击实验和热疲劳试验。在温度为1100℃,CH_4流量为0.36L/min,H_2流量为1.16L/min的工艺条件下,得到了致密的TiC涂层,且沉积速率达0.7μm/min,并给出了涂层厚度与工艺参数之间的经验关系式。在高功率密度(最大值达226MW/m~2,作用0.6s)电子束热冲击下,TiC涂层从基体(石墨、钼、316L不锈钢)脱落,且316 L不锈钢基体被熔化、蒸发。在900℃到-246℃之间的热循环实验下,TiC/316L不锈钢表现出极差的抗疲劳特性,仅在2次热循环之后,就有大量TiC涂层从316L不锈钢基体脱落;虽然TiC/石墨的涂层中有大量网状裂纹形成,但是,在200次热循环之后,TiC涂层与基体仍结合很好;TiC/钼有很好的抗疲劳特性,在200次热循环之后,材料仍没有任何损伤。     

中子辐照后B_4C/Al材料断裂机理分析

为评价辐照对B_4C/Al中子吸收材料力学性能的影响,测试了B_4C/Al中子吸收材料辐照前后的硬度、拉伸性能,并采用扫描电子显微镜(SEM)进行断口观察和显微组织分析,探讨断裂机理。结果表明:辐照后B_4C/Al中子吸收材料洛氏硬度升高,屈服强度上升37 MPa,抗拉强度上升32 MPa,断裂伸长率下降3.6%;辐照前后B_4C/Al中子吸收材料拉伸试样均为脆性断裂;辐照后Al基体的位错增殖以及B_4C颗粒与Al基体界面变化是导致B_4C/Al中子吸收材料力学性能提高的主要原因。     

充氚不锈钢中氦泡长大行为的加热效应

以室温贮存经历的充氚不锈钢试样为研究对象,计算了充氚不锈钢中氚、氦浓度的深度分布,利用透射电镜观察了充氚不锈钢在加热过程中氦泡的演化行为。结果表明:在氚压0.131MPa、780℃充氚8h后,不锈钢中氚在深度方向分布均匀,平均浓度为110μL/L;在空气室温环境下放置6a后,不锈钢中氚衰变的氦浓度在深度方向分布均匀,平均浓度为60μL/L;对充氚不锈钢加热处理后,在550℃/1h时效即可观察到氦泡;在950℃/1h和1050℃/1h时效时,氦泡明显长大,大的可达100nm,小的可达30nm,在晶界、晶内和位错处均可见氦泡。     

充氚不锈钢微观组织及断裂特征

采用力学拉伸实验测定充氚不锈钢的断裂强度值,采用拉伸断口进行SEM观察和正电子湮灭(PAT)分析,采用TEM动态拉伸实验观察和记录材料在微观断裂过程中的行为,通过对比分析氚对不锈钢断裂过程的影响。结果表明,高温充氚后,室温存放2a,样品中氚衰变产生的氦累积已达约30ppm;氚、氦使样品断裂强度降低,内部缺陷增多,正电子寿命变长。TEM观察未发现明显的氦泡组织;动态拉伸实验表明,充氚促进裂纹尖端位错的发射和增殖;HR-1、HR-2不锈钢微观断裂过程相似,可表述为氚致微裂纹的形核-形成微空洞-微空洞长大-空洞连接(断裂)。氚、氦使无位错区减小甚至消失。     

氚在真空贮存容器材料中的吸附和渗透行为

研究了贮存氚靶约4 a和20 a的两个316 L不锈钢真空贮存容器(以下简称贮存容器)及其垫片材料对氚的吸附行为,并对氚在贮存容器材料中的渗透速率进行了测量和分析。结果表明,贮存容器外表面氚污染为几十Bq/cm2,不锈钢与陶瓷中吸附的氚活度均为106Bq/g;热解吸至1 273 K过程中,材料中99%的氚释放出来;在解吸出的氚中,陶瓷中的HTO比例高于不锈钢;贮存温度对氚靶贮存容器的渗氚速率有较大影响,夏季约为冬季的4倍。上述结果提示,氚在贮存容器材料内表面吸附后,一部分会向晶格扩散并滞留下来;另一部分则透过材料向外环境渗透,其中温度是影响氚向外环境渗透的主要因素之一。     

充氚不锈钢中氦行为的PAL和TEM研究

对充氚和未充氚的抗氢-2(HR-2)不锈钢样品进行退火处理,利用正电子湮没寿命谱(PAL)以及透射电镜(TEM)等技术探讨不锈钢中氦和微缺陷的相互作用。未充氚样品中,退火温度对缺陷态的影响主要表现为偏聚物在晶界的析出。充氚样品实验中,退火温度小于300℃时,充氚不锈钢中的He原子主要通过自捕获机制在晶内缺陷处聚集成泡;热处理温度为300～600℃时,充氚不锈钢中的He原子主要通过热迁移的方式迁移至晶界导致晶界宽化,但晶界处无明显的He泡形成;热处理温度大于600℃时,热平衡空位开始发挥作用,与聚集在晶内缺陷处的He原子结合形成He泡,且随退火温度的升高,He泡有明显聚合长大的现象。     

Effect of Coating and Heat Treatment on High Temperature Burst Property of Stainless Steel Thin-walled Tube

In order to investigate the high temperature burst behavior and effect of coating and heat treatment on burst properties of stainless steel thin-walled tube for pressurized water reactor (PWR) and supercritical water-cooled reactor (SCWR) under the simulated LOCA (loss of coolant accident) conditions, the transient-heating burst tests of original, heat treatment and coated tube specimens were carried out under the simulated LOCA conditions by using the high temperature burst facility. The data of high temperature burst properties based on three kinds of 316L stainless steel tubes and the relationships between burst strength and total circumference elongation (TCE) with temperature were obtained under the conditions of 600-1200 ℃ and heating rate of 5 ℃/s, meanwhile, the fracture morphology and microstructure of burst test specimens were analyzed. The results of the burst test show that heat treatment temperature of coating preparation is the main reason for the decrease in burst strength, and the coating has little effect on the high temperature burst strength.     

Simulation of the effects of different substrates,temperature,and substrate roughness on the mechanical properties of Al_2O_3 coating as tritium penetration barrier

Residual thermal stress in the system is a serious problem that affects the application of tritium permeation barrier coatings in fusion reactors. The stress not only determines the adhesion between coating and substrate, but also changes the properties of the material. In this study,finite element analysis was used to investigate the relationship between the residual thermal stress and the mechanical properties of Al_2O_3 tritium penetration barrier systems. Moreover, the residual thermal stress influenced by factors such as different substrates, temperature, and substrate roughness was also analyzed. The calculation showed that the hardness and elastic modulus increased with increasing compressive stress. However, the hardness and elastic modulus decreased with increasing tensile stress. The systems composed of Al_2O_3 coatings and different substrates exhibited different trends in mechanical properties. As the temperature increased, the hardness and the elastic modulus increased in an Al_2O_3/316 L stainless steel system; the trend was opposite in an Al_2O_3/Si system.Apart from this, the roughness of the substrate surface in the system could magnify the change in hardness and elastic modulus of the coating. Results showed that all these factors led to variation in the mechanical properties of Al_2O_3 tritium permeation barrier systems. Thus, thedetailed reasons for the changes in mechanical properties of these materials need to be analyzed.     

涂层及热处理对不锈钢薄壁管高温爆破性能的影响

为研究压水堆及超临界水冷堆失水事故工况下堆用不锈钢薄壁管的高温爆破行为及涂层与热处理对高温爆破性能的影响，利用自行研制的高温爆破试验装置，开展了316L不锈钢原始管、热处理管及涂层管在模拟失水事故温度条件下的瞬态加热高温爆破试验，获得了3种不锈钢样品管在600～1 200 ℃、升温速率为5 ℃/s条件下的高温爆破性能数据及爆破强度和周向延伸率随温度的变化关系，并对破口形貌和微观组织进行了观察分析。结果表明：涂层制备时的热处理温度是高温爆破强度降低的主要影响因素，而涂层本身对高温爆破强度几乎没有影响。     

Effect of Cr2O3 nanosheet insertion on the deuterium permeation behavior of a Cr-Zr-O coating

In this study, a Cr₂O₃ nanosheet (Cr₂O₃ NS) inserted Cr-Zr-O coating was developed as a hydrogen isotope permeation barrier. The Cr₂O₃ NSs, fabricated by rapid heat treatment, were amorphous with a thickness of only several nanometers. These Cr₂O₃ NSs were then incorporated into a Cr-Zr-O multi-metal oxide composite coating via a dip-coating method to form a coating. The effect of the Cr₂O₃ NS concentration on the morphology, microstructure and deuterium permeation resistance of the coating was studied. With the addition of 1.0 g l−1 Cr₂O₃ NSs, compared with the Cr-Zr-O coating without NSs, the permeation reduction factor of the resultant coating was enhanced from 249 °C to 575 °C at 500 °C. The coating, with a thickness of nearly 193 nm, achieved a comparable deuterium resistance that was above two orders of magnitude higher than the steel substrate. The results show that ceramic NSs can serve as effective fillers for enhancing the coating performance when functioning as a hydrogen isotope barrier.     

Microstructure characterization of oxidation of aluminized coating prepared by a combined process

Alumina layer is a good candidate for the tritium penetration barrier that is important in the control of tritium losses due to permeation through structural materials used in high-temperature gas-cooled reactors and in fusion reactors. This paper describes the microstructure of the oxide film of the tritium penetration barrier formed on 316L stainless steel, which was prepared by a combined process, namely, aluminizing and oxidizing treatments using a double glow plasma technology. Microstructure and phase structure of the coatings investigated were examined by scanning electronic microscope (SEM), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM), respectively. The chemical composition and the chemical states of Al, O elements in the oxidation film were identified by X-ray photoelectron spectroscopy (XPS). After aluminization, the typical microstructure of the coating mainly consisted of an outer high aluminum-containing intermetallic compound layer (Fe₂Al₅ and FeAl) and intermediate ferritic stainless steel (α Fe(Al))layer followed by the austenitic substrate. After the combined process, an oxide layer that consisted of Al₂O₃ and spinel FeAl₂O₄ had been successfully formed on the aluminizing coating surface, with an amorphous outmost surface and an underlying subsurface nanocrystalline structure.