稀有金属材料加工技术进展

介绍了目前我国所掌握的稀有金属材料生产技术及常规板、棒、丝、管材制备技术现状.提出了稀有金属材料未来发展的三大趋势:即:产品设计、材料精确制备与成形加工趋向一体化;新技术及新产品的开发与具体应用结合更加紧密;向“规格大型化、品种多样化、性能优质化和经济低成本化”的“四化”方向发展.强调我国亟需发展的稀有金属精深加工技术为稀有金属带箔材精加工和近净成形深加工两大技术.发展稀有金属加工技术,有利于提高稀有金属产品的成品率及利用率,促进我国稀有金属从资源优势向技术优势转变;发展加工技术有利于产业技术升级,加速产业链由低端向高端延伸,促进产业结构的优化与调整.     

铌基高强合金的微观组织和力学性能

按预定成分制备Nb-Ta-W-Zr预合金坯条,经二次真空电子束熔炼、大变形量锻造开坯加工成合金棒材。用扫描电镜、Olympus光学显微镜、万能电子拉伸试验机和真空高温拉伸试验机对该合金的微观组织和力学性能进行研究。结果表明:该合金是固溶强化和第二相沉淀强化共同作用的高强铌合金,在1300℃仍有较高的强度和塑性。     

B粉对分步法制备MgB2超导体的影响

通过分步反应法,利用晶态B粉和无定形B粉分别与Mg粉反应制备了MgB2超导体。其中分步反应法的第1步采用不同状态的B粉与Mg粉按原子比Mg:B=1:4混合,对于掺杂的样品另加5%,8%(质量分数)的SiC,采用900℃,30min或800℃,1h进行高温热处理。第2步是补充Mg粉,使Mg:B=1:2,均混的粉末经装管拉拔后进行第2步750℃,2.5h热处理。通过XRD、SEM研究样品的相组成、微观结构。采用标准四引线法测定了样品的I-V曲线。结果表明:晶态B粉与Mg粉可在第1步的热处理过程中生成大量低反应活性的MgB4。从微结构分析发现晶态B粉制备的样品具有更好的晶粒连通性,从而也得到了更稳定的I-V关系曲线。     

鄂尔多斯盆地铁边城地区长8沉积相研究

铁边城地区位于陕西吴旗县境内,构造处于鄂尔多斯盆地陕北斜坡西部。研究区长8储层为一套以碎屑岩为主的内陆湖泊三角洲相沉积。本文以测井相分析及岩心观察的岩石相标志为基础,通过砂地比值分布规律、单井剖面的相序分析,对鄂尔多斯盆地铁边城地区长8油层组沉积相类型及发育规律进行综合研究。结果表明铁边城地区长8期的主要沉积体系属于"浅水"湖泊-三角洲沉积体系,发育三角洲平原和三角洲前缘亚相,主要微相类型包括有三角洲平原分流河道、分流河道间、天然堤微相和三角洲前缘水下分流河道、分流间湾、水下天然堤微相。根据沉积微相展可以得出研究区的沉积模式。     

A theory of avalanche breakdown during anodic oxidation

The breakdown characteristics during anodization of valve metals are interpreted in terms of a recent model. The model quantitatively takes into account, in addition to the oxidation ionic current, the current transported by the electrolyte incorporated into the oxide and the avalanche electronic current. The primary electronic current of the avalanche is attributed to the electrons released by the electrolyte species in the oxide.     

天然气长输管道工艺场站噪声的治理

天然气长输管道的部分工艺场站(不包括压气站)在生产运行过程中存在噪声超标现象,如何有效地控制其噪声对外界的影响,是工艺场站在环境保护方面应该面对的问题;结合其生产运行的实际,提出治理措施,降低其噪声对外界的影响。     

Deformation behavior of isothermally forged Ti–5Al–2Sn–2Zr–4Mo–4Cr powder compact

The isothermal deformation behavior of hot isostatic pressed (HIPed) Ti–5Al–2Sn–2Zr–4Mo–4Cr(Ti-17) powder compact was investigated by compression testing in the temperature range of 810–920 °C and constant strain rate range of 0.001–1 s^?1. The true stress–true strain curves of the powder compact exhibit flow oscillation and flow softening phenomenon in both beta field and beta + alpha field. The flow softening behavior is related to the globularization of the primary acicular microstructure and deformation heating. The apparent activation energy for deformation in beta field is estimated to be 149 kJ mol^?1, indicating that the deformation is controlled by diffusion. The high apparent activation energy of 537 kJ mol^?1 for deformation in beta + alpha field may be related to the dynamic recrystallization of the primary acicular microstructure. Constitutive equations with the form of Arrhenius-type hyperbolic-sine relationship are proposed to delineate the peak flow stress as a function of the strain rate and the temperature for isothermal forging HIPed Ti-17 powder compact.     

Meso-scale analysis of the creep behavior of hydrogenated Zircaloy-4

During dry storage, creep is the most likely degradation mechanism for spent Zircaloy fuel cladding. The fuel cladding integrity during dry storage depends on the amount of oxidation, irradiation hardening and hydrogen-uptake during in-reactor operation. In this paper, the effect of hydrogen on the creep behavior of Zircaloy-4 cladding material was investigated at different temperatures. Depending on temperature, hydrogen can be found in the sample in solid solution and/or hydride. To capture this phenomenon, a numerical mesoscale model of the hydrogenated material has been built using the Finite Element (FE) Method. The numerical setup explicitly describes the hydrides as an inclusion in a hydrogenated Zircaloy-4 matrix. The matrix creep behavior follows a combined Norton-Bailey and Norton creep rules whereas the hydrides are considered to be elastic material. The creep law was defined in FE Code ABAQUS using the user subroutine CREEP. The comparison of predicted creep behavior obtained from numerical modeling showed good agreement with the results reported in literature. The predicted creep behavior shows a significant effect of hydrides morphology. Particularly, our model is able to seize the competition between the creep strain rate enhancement induced by hydrogen in solid solution and its reduction due to precipitated hydrogen.     

奥维互动地图在工程施工中的应用

结合郑徐高铁和栗高高速公路工程项目,对奥维地图在工程施工中的应用方法和作用进行了详细的阐述,并提出了一些观点。主要内容包括:CAD平面图导入奥维互动地图的两种方法(即关联点坐标转换法和横轴墨卡托投影坐标法)的应用及其各自的优势分析;奥维地图在工程前期交接桩、项目前期临建方案的编制、控制网加密中网形的优化设计和水准路线优化设计等方面的应用。这充分显现了该软件在工程施工中的高效性和便利性等优势,对其他工程建设可提供借鉴。