B4C/6061Al中子吸收材料微观结构及其力学性能研究

本文采用真空热压后轧制的方法(VHPR)成功制备了混合粒径增强的B4C/6061Al中子吸收材料,B4C含量分别为0vol.%、20vol.%、30vol.%和40vol.%。对中子吸收材料的微观组织形貌及其界面行为进行了观察,对材料的拉伸强度及断口进行了测试分析,对强化机理进行了讨论。试验结果表明：6061Al基体构成了空间网络结构,界面结合处为冶金结合,界面扩散层厚度可达5um,随着B4C颗粒含量的增加,中子吸收材料内部小粒径B4C颗粒出现了局部的团聚现象。中子吸收材料的强度呈现先增加后降低的趋势,断裂方式主要为沿界面开裂和B4C颗粒的解理断裂。中子吸收材料经过多道次的交叉轧制以后,基体铝晶粒得到细化,在B4C颗粒周围出现了大的塑性变形区,交叉轧制同时也提高了B4C颗粒在基体铝中的分布均匀性,减少材料内部缺陷。     

B_4C/6061Al中子吸收材料微观结构及其力学性能

采用真空热压后轧制的方法(VHPR)成功制备了混合粒径增强的B4C/6061Al中子吸收材料,B4C含量分别为0%、20%、30%和40%(体积分数)。对中子吸收材料的微观组织形貌及其界面行为进行了观察,对材料的拉伸强度及断口进行了测试分析,对强化机理进行了讨论。结果表明:6061Al基体构成了空间网络结构,界面结合处为冶金结合,界面扩散层厚度可达5μm,随着B_4C颗粒含量的增加,中子吸收材料内部小粒径B_4C颗粒出现了局部的团聚现象。中子吸收材料的强度呈现先增大后减小的趋势,断裂方式主要为沿界面开裂和B_4C颗粒的解理断裂。中子吸收材料经过多道次的轧制以后,基体铝晶粒得到细化,在B_4C颗粒周围出现了大的塑性变形区,轧制同时也提高了B_4C颗粒在基体铝中的分布均匀性,减少材料内部缺陷。     

B4C/Al中子吸收材料的拉伸性能及断口特征

通过B4C/Al中子吸收材料在室温至350℃的拉伸试验,分析了该材料的拉伸断裂主要影响因素,阐述了B4C颗粒粒度对拉伸断裂的影响.结果表明,温度对B4C/Al材料拉伸性能有明显影响,该中子吸收材料是低塑性材料,但与国外同类材料相比拉伸性能优良;大颗粒B4C与基体的协调变形能力差,拉应力下B4C和基体铝界面易产生剪切应力,使其与基体脱离开;B4C/Al材料在拉伸过程中,裂纹首先在大颗粒B4C与Al基体的界面处产生.     

过渡元素改善B_4C/Al材料界面润湿性的机理研究（英文）

B_4C/Al复合材料是目前最理想的中子吸收材料,但工业上常用的液态搅拌法制备过程中存在着界面润湿性差的问题。结合实验及第一性原理的方法,通过研究Al(111)/AlB_2(0001)和Al(111)/TiB_2(0001)界面的结构来分析工业上添加过渡元素Ti对B_4C/Al界面润湿性的改善机制。通过计算发现,Al(111)/TiB_2(0001)界面相对Al(111)/AlB_2(0001)界面具有更高的粘附功值,说明其界面结合更强。进一步对比Ti掺杂二硼化物和AlB_2的偏态密度结构,发现Ti掺杂体具有较低的反键态,表明Ti-3d和B-2p轨道电子杂化后,在B、Ti原子间形成了较强的化学键,从而促进了Al(111)/TiB_2(0001)界面处的强结合作用,提高了Al(111)/TiB_2(0001)界面粘附功,故而改善了B_4C/Al界面的润湿性。根据同样的理论依据,V掺杂体也具有较低的反键态,V和B之间的强结合效果或许能够改善B_4C/Al界面的润湿性,成为又一理想的溶体改性掺杂元素。     

基于SHPB试验的B4C/Al复合材料动态力学性能研究[*]

B4C/Al是一种新型金属复合陶瓷材料,相比于传统陶瓷材料,B4C/Al 复合材料具有低密度、高硬度、高韧性、低成本等优点,常被应用于装甲防护领域。为研究B4C/Al复合材料在动态加载下的力学性能,论文通过分离式霍普金森压杆（SHPB）实验和电镜扫描（SEM）等技术,获得了材料在不同冲击速度下的典型波形图、应力应变曲线,以及微观环境下的断口形貌;研究了不同应变率下材料的应力应变曲线特征和破坏模式,同时讨论了Al含量对材料的动态压缩强度的影响规律。研究结果可为B4C/Al复合材料的设计和应用提供参考。     

B4C/Al中子吸收板腐蚀过程中的起泡研究

根据亨利定律,建立了B4C/Al中子吸收板包壳腐蚀起泡的模型,计算了孔隙半径、温度对起泡的影响,并利用孔隙毛细管效应分析了孔隙对中子吸收板起泡的影响.结果表明:孔隙半径越小,腐蚀产生的氢气压力越大,B4C/Al中子吸收板包壳更易起泡;温度对腐蚀产生的氢气压力影响非常小,而孔隙半径是影响氢气压力的主要因素;氢气持续产生并在孔隙毛细管中积聚,是包壳产生起泡的动力;水分容易通过孔隙毛细管在B4C/Al芯体中扩散,可导致Al腐蚀,引起包壳起泡.     

过渡元素改善B4C/Al材料界面润湿性的机理研究

B₄C/Al复合材料是目前最理想的中子吸收材料,但工业上常用的液态搅拌法制备过程中存在着界面润湿性差的问题。本文结合实验及第一性原理的方法,通过研究Al(111)/AlB₂(0001)和Al(111)/TiB₂(0001)界面的结构来分析工业上添加过渡元素Ti对B₄C/Al界面润湿性的改善机制。通过计算发现,Al(111)/TiB₂(0001)界面相对Al(111)/AlB₂(0001)界面具有更高的粘附功值,说明其界面结合更强。进一步对比Ti掺杂二硼化物和AlB₂的偏态密度结构,发现Ti掺杂体具有较低的反键态,表明Ti-3d和B-2p轨道电子杂化后,在B、Ti原子间形成了较强的化学键,从而促进了Al(111)/TiB₂(0001)界面处的强结合作用,提高了Al(111)/TiB₂(0001)界面粘附功,故而改善了B₄C/Al界面的润湿性。根据同样的理论依据,V掺杂体也具有较低的反键态,V和B之间的强结合效果或许能够改善B₄C/Al界面的润湿性,成为又一理想的溶体改性掺杂元素。     

碳化硼屏蔽吸收芯块的研制及其在快堆中的性能考核

用碳热还原法制取高化学剂量的B4C细粉,细粉经气流粉碎制得微米级B4C粉末。经致密化工艺得到碳化硼屏蔽吸收芯块。芯块达到了中国实验快中子反应堆(CEFR)的技术要求。碳化硼芯块在快堆中经过383有效天的考核,快中子通量达3.8×1022cm-2(中子能量E>1.602×10-14J,即>0.1 MeV),证明其具有高的辐照稳定性,符合使用要求,可以在CEFR堆中使用。     

半固态热等静压Al/B4C复合材料液相流动行为与致密化机理

铝基碳化硼复合材料是一种重要的中子吸收材料。为了制备具有更高密度的铝基碳化硼材料,研究采用粉末冶金半固态热等静压方法制备了含量为30%碳化硼的铝基碳化硼材料,采用WANCE100型材料力学性能试验机和SIRION200型扫描电镜研究了复合材料的力学性能及显微形貌。结果表明：半固态热等静压工艺可制备获得接近理论密度的Al/B4C复合材料;虽然Al/B4C材料抗拉强度可提升至约300Mpa,但过高碳化硼含量也使得该材料脆性特征十分明显;研究同时采用间接的方法观察到了半固态工艺过程中生成的液相,该液相不仅可改善碳化硼颗粒与铝基体的结合性,在高温高压下液相的流动还起到填充复合材料内部空隙的作用。半固态热等静压工艺过程中产生的液相是复合材料密度和机械性能提升的主要原因。     

B_4C/6061Al中子吸收材料FSW接头的纳米压痕和拉伸性能研究

采用粉末冶金的方法制备了30vol%B_4C/6061Al中子吸收材料板材。通过搅拌摩擦焊(FSW)的方法对4 mm厚30vo1%B_4C/6061A1中子吸收材料板材进行对接焊接,获得了表面成形良好的焊缝。采用纳米压痕法对FSW焊接接头的焊核(WZ)、热力影响区(TMAZ)、热影响区(HAZ)和母材(BM)4个区域中的微区力学性能进行研究,对焊接接头的拉伸性能进行了测试。运用扫描电镜对压痕的微观形貌和拉伸断口进行表征。结果表明:在同一区域中,随着距颗粒/基体界面距离d(d11μm)的增加,微区的硬度和弹性模量总体呈现降低趋势。在微区数值均值化后,不同区域的硬度和弹性模量由高到低为WZ、TMAZ、BM和HAZ,压入功恢复率在WZ、TMAZ、HAZ和BM依次为28.10%、25.14%、31.76%和29.30%。在焊接接头不同区域出现性能差别的原因是由于在FSW过程中不同区域的塑性变形程度和热循环作用不同导致的,FSW接头强度可达母材的85.7%,断裂部位在HAZ区。     

Research Progress of Metal-Based Shielding Materials for Neutron and Gamma Rays

The radiation generated by nuclear reaction is harmful to human body and equipment,thus the radiation shielding materials that employ the shielding ability from neutron and gamma rays are the best candidates according to application situations and radiation sources.In this paper,the researches of metal-based neutron and gamma rays or multiple purpose shield-ing materials are systematically summarized,and the respective and principal problems of these materials with respect to shielding effectiveness and other performances,such as corrosion,mechanical properties,manufacture,etc.,are discussed.Finally,the prospect of shielding materials is outlined,which suggests that the development of highly efficient and multiply functional radiation shielding materials with good environmental compatibility is one of the future development trends.     

抗辐照材料研究进展

用于核反应堆的新候选材料研发是一项重要任务。由于反应堆环境恶劣,堆芯材料在高温下应具有良好的综合性能,如良好的强度、延展性、耐腐蚀性能和耐辐照性能等。此外,还应考虑低中子吸收横截面和中子活化。典型的空间核反应堆核心材料的选择主要由工作温度决定。随着反应堆设计工作温度的升高,一般以316不锈钢、镍基高温合金、氧化物分散强化（ODS）钢、铌合金、难熔金属和SiC陶瓷的顺序来选择设计堆芯材料。此外,高熵合金已经引起核领域的广泛关注。本文综述了以上不同材料体系在辐照过程中的力学性能演变,为进一步提升抗辐照性能提供研究指导。     

Application of In Situ Neutron Diffraction to Characterize Transient Material Behavior in Welding

A fundamental understanding of the transient and nonequilibrium material behavior during welding is essential in the pursuit of process control and optimization to produce defect-free, structurally sound, and reliable welds. The deep penetration capability of neutrons into most metallic materials makes neutron diffraction a unique and powerful tool in understanding the material structures and properties. However, the inadequate neutron flux limits its application in time-resolved study of transient material behavior. This article highlights recent developments toward in situ time-resolved neutron diffraction measurement of material behavior during welding with two examples: (I) measurement of the transient temperature and thermal stresses during friction-stir welding of an aluminum alloy and (II) measurement of the solid-state phase transformation behavior of an advanced high-strength steel under thermal conditions comparable to the welding processes. These newly developed experimental approaches can be broadly applied to other welding or thermomechanical processes for time-resolved measurement of the fast-changing material state in structural metals.     

中子衍射技术测量残余应力的研究进展

随着我国中子大科学装置技术的发展和进步,中子衍射技术已广泛应用于航空、航天、核电、汽车等各领域。本文介绍中子衍射残余应力测量原理及相关基础知识,与其他深部应力测试结果进行对比,中子衍射具有高穿透力,是无损获得材料及工程部件内部三维应力的最有效方法,尤其适用于局域位置的应力测量,在工程部件残余应力测试与分析,揭示制造加工工艺或使用过程中残余应力的演变及相关的形变、相变机理方面独具优势,相应原位实验与测试技术的发展为材料研制及性能评价提供重要的技术手段,中子衍射技术将在材料与工程领域发挥不可替代的作用。     

石墨烯基电磁功能材料

二维纳米材料拥有优异的电学、热学和力学性能,在高技术领域展现出巨大的应用潜力。其中,石墨烯具有大的比表面积和高的载流子浓度,是当代科技关注的对象。系统地展示了石墨烯基电磁功能材料的电磁响应机制以及吸波与屏蔽性能。在研究的电磁波频段(2~18 GHz),电磁损耗一般包括电导损耗、多重弛豫、磁共振及磁涡流。详细地介绍了这四种电磁损耗行为的物理形成机制和响应特性,总结了不同石墨烯基电磁功能材料的电磁损耗来源,并提出了设计高性能电磁功能材料的策略。随后,展示了高性能电磁功能材料的应用标准,给出了微波吸收与电磁屏蔽的响应规律,提出了两种改善电磁响应性能的方法。在电磁功能材料性能方面,介绍了石墨烯基电磁功能材料在微波吸收和电磁屏蔽领域最新研究进展。所涉内容涵盖石墨烯单相材料、异质材料及高温介电特性和电磁响应。另外,还系统地分析了石墨烯基电磁功能材料当前发展所面临的关键问题,并展望了未来的研究与发展方向。     

Gd含量对06Cr19Ni10不锈钢热中子屏蔽性能及微观组织的影响

针对核电站对中子屏蔽材料结构功能一体化的需求，开展了Gd含量对06Cr19Ni10不锈钢热中子屏蔽性能及微观组织的影响研究，通过热中子屏蔽计算仿真分析，并以此为指导开展了不同Gd含量的Gd-06Cr19Ni10熔炼和轧制试验，采用OM、SEM等方法对不锈钢试样进行分析检测，结果表明：Gd的添加可以细化06Cr19Ni10不锈钢晶粒，但易形成脆性的Ni-Gd第二相，随着Gd含量的提高，Ni-Gd第二相面积百分数也明显增加，使得06Cr19Ni10不锈钢塑性下降，轧制性能明显降低。结合热中子屏蔽计算分析和轧制试验结果，认为Gd含量为1.7wt.%左右时Gd-06Cr19Ni10可以获得较为均衡的热中子屏蔽性能和材料轧制性能。     

Textured Bi2Sr2Ca2Cu3O10+y tiles manufactured from sintered and plasma-sprayed precursors for magnetic shieldingtiles manufactured from sintered and plasma-sprayed precursors for magnetic shielding

Superconducting magnetic shields have potential weight advantages over conventional materials as efficient, light, shielding materials. Shielding properties in high fields depend on many material features, including alignment, critical current densities, and flux pinning. Diffusion texturing can produce grain alignment with the c-axis parallel to the sheet plane. In this article, the superconducting tile is made by bonding the ceramic precursor, SrCaCu₂, to a metal substrate before texture growth with Pb-Bi-O. The bonding can be produced by sintering or by plasma spraying. After diffusion texture growth, a tile with a superconducting transition temperature of 110 K and a critical current density greater than 2500 A/cm² has been manufactured and characterized.     

Optimization of arc welding processes using a neural network

X-ray and neutron diffractometric methods are described for the early-stage diagnosis of materials. A comparison is made between traditional and innovative technologies, which aim at being included amongst the NDT methods usable on-site. Emphasis is also placed on the gradual removal from instruments of structural restraints, with a tendency towards anthropomorphic functionalities and flexibility. Prototype production and conceptual schemes are presented and discussed. Conceptual tests, applications and case studies are shown as per the state of the art. Particular reference is made to results obtained from data collected from materials containing welding (e.g. titanium alloys, P22, T92 and P92 steel) and micro- and nano-structural alterations (e.g. ceramics, glass and other materials). These results indicate the meaning and usefulness of the early observation of effects induced in the reticolum of metals by loads, residual stress and structural micro/nano variations. It follows that reticular measurements and the diffractometric methods related to them are onlythose currently available to obtain appropriate early-stage diagnosis. A discussion is provided of photonic (X-ray) and neutronic diffraction with corresponding limits and advantages. The hypothesis of creating a new mobile diagnostic device intended for the application of neutron diffraction is introduced.     

Influence of nitrogen in the shielding gas on corrosion resistance of duplex stainless steel welds

The influence of nitrogen in shielding gas on the corrosion resistance of welds of a duplex stainless steel (grade U-50), obtained by gas tungsten arc (GTA) with filler wire, autogenous GTA (bead-on-plate), electron beam welding (EBW), and microplasma techniques, has been evaluated in chloride solutions at 30 °C. Pitting attack has been observed in GTA, electron beam welding, and microplasma welds when welding has been carried out using pure argon as the shielding gas. Gas tungsten arc welding with 5 to 10% nitrogen and 90 to 95% argon, as the shielding gas, has been found to result in an improved pitting corrosion resistance of the weldments of this steel. However, the resistance to pitting of autogenous welds (bead-on-plate) obtained in pure argon as the shielding gas has been observed to remain unaffected. Microscopic examination, electron probe microanalysis (EPMA), and x-ray diffraction studies have revealed that the presence of nitrogen in the shielding gas in the GTA welds not only modifies the microstructure and the austenite to ferrite ratio but also results in a nearly uniform distribution of the various alloying elements, for example, chromium, nickel, and molybdenum among the constitutent phases, which are responsible for improved resistance to pitting corrosion.     

民用核安全设备焊接材料验收

民用核安全设备焊接材料的验收是指民用核安全机械设备制造和安装阶段RCC-M规范级设备用焊接材料的验收,焊接材料验收的目的是为了保证核岛机械设备在制造和安装过中所用的成批焊材具有稳定的质量,并保证其质量符合订货技术条件的要求。主要探讨了民用核安全设备焊接材料验收的内容以及焊接材料验收的步骤,为民用核安全设备焊接材料的验收提供参考。