金属凝固细晶技术及发展

介绍了凝固过程控制在材料加工技术中的地位,阐述了凝固过程的研究内容和凝固组织细化的作用,并对金属凝固组织细化技术中的浇注过程和传热条件控制方法、化学处理方法、机械处理方法以及外加物理场方法作了简单评述;认为温度扰动、成分扰动、外加超声波、脉冲电流或脉冲磁场不仅能有效地细化金属凝固组织,还可以避免其他细化方法对环境和金属材料本身的污染,有利于材料的循环利用.     

On the principles of the deformation methods of grain refinement in aluminum alloys to ultrafine size: II. Ultrafine-grained alloys

The applicability and efficiency of the principles of optimum structural heterogeneity and stage-by-stage grain refinement in relation to the formation of an ultrafine-grained (UFG) structure (with a grain size smaller than 1 μm) in bulk billets during severe plastic deformation are analyzed. The evolution of the criteria of these principles is considered when going from a fine-grained structure to a UFG structure and from conventional deformation treatment to severe deformation treatment. The dependence of the intrinsic mechanisms of grain refinement to ultrafine size on the initial structure of an alloy, including the heterogeneity of the initial structure, is analyzed.     

On the principles of the deformation methods of aluminum-alloys grain refinement to ultrafine size: I. Fine-grained alloys

Basic principles of the optimum heterogeneity of the structure and its step by step refinement, which underlie the design of aluminum-alloys structure required for processing the fine-grained structure (with a grain size from ～10–15 to 1 μ m) and the thermomechanical methods for its obtaining are considered. The physical nature of these principles is analyzed, their specific features for heat-treatable and non-heat-treatable alloys are discussed, and their realization in intermediate and two-stage thermomechanical treatment is illustrated. The related effects are considered and the conclusion is made on the expediency of combining both principles in one processing of bulk fine-grained workpieces.     

The laser-induced combustion synthesis of iron-oxide nanocomposite coatings on aluminum

The potential of synthesizing nano-structure coatings on aluminum cast alloys during laser surface engineering has been explored based on combustion synthesis and underlying rapid-solidification principles. The roles of cooling rate, heterogeneous nucleation site density, and grain multiplication in structure refinements are well known. By combining combustion synthesis and laser surface engineering, refinement to nanostructure is envisioned.     

带镶件球状塑件的两种注射模结构设计对比

基于"带镶件球状塑件的两例注射模结构设计"实例,从设计、制造到生产,进行了详细的对比和分析,以期说明注射模结构设计,越简单越好这个极其重要的基本原则。     

Mixed site occupancies in the μ phase

The μ phase has been studied in different systems (Ta–Ni, Mo–Co, Nb–Ni) as a function of the composition. In addition, its stability in the Mn–Si system has been investigated. The atom distribution on the five different sites of the crystal structure has been obtained from Rietveld refinement of X-ray powder diffraction data. These experimental data are compared to the values computed from first principles results and from existing Calphad assessments of the different systems. Conclusions are drawn concerning the model to be chosen for describing this phase.     

Improving the carbon macrosegregation in high-carbon steel by an electric current pulse

Thus far, the relationship between the macrosegregation and refinement of solidification structures in metals is not clearly understood. In this paper, the effect of an electric current pulse (ECP) on the refinement of the solidification structure as well as carbon macrosegregation in high-carbon steel was investigated. The experimental results revealed that if central porosity exists in the solidification structure, the carbon macrosegregation in high-carbon steel cannot be improved by applying an ECP, although increased equiaxed dendrites and a reduced primary dendritic arm in a solidification structure were obtained after an ingot was exposed to an ECP. In contrast, after central porosity was eliminated, carbon macrosegregation was improved through the refinement of the solidification structure in high-carbon steel through the use of an ECP.     

Effect of the deformation zone on the structure refinement in metals

Structure refinement in pure metals has been considered on the base of the concept of large deformations [1] with allowance for the role of intracrystallite and intercrystallite components. The effect of a parameter expressed as the ratio of the area of the deformation zone surface to its volume on the deformation mechanisms and the level of structure refinement has been demonstrated. A model of structure refinement in metals during cold deformation has been proposed.     

Effective safety training programs for aluminum cast shops

To compete effectively in a global economy, aluminum casting operations must develop and maintain a qualified and competent workforce. A significant part of this effort must center on employee training, especially safety training. In addition to providing employees with accurate information, effective safety training programs will recognize certain principles governing human behavior. This paper reviews topical content appropriate for safety training programs to be used in aluminum casting operations and suggests ways to enhance the effectiveness of such training by incorporating principles of human behavior. For more information, contact J.M. Ekenes, Hydro Aluminum Hycast, Spokane, Washington; e-mail jmekenes@jmekenes@mstar2.net     

脉冲电流细化金属凝固组织研究综述

评述了近年来脉冲电流细化金属凝固组织方面的研究进展,总结探讨了脉冲电流影响金属凝固组织机理的不同观点.指出脉冲电流细化金属凝固组织机理尚存争论,但是技术已经比较成熟,已具备工业应用的基本条件.     

磁流变阻尼器设计中的基本问题分析

详细讨论了磁流变阻尼器的设计过程，对于在设计中的流体、结构选择等问题进行了探讨，对主要零件的结构参数和材料选择做了分析，通过Bingham模型计算分析，得到不同的结构尺寸对阻尼力和阻尼系数的增加存在很大差异，给出了设计尺寸的选择要求，并提出了设计中应遵循的基本原则和设计步骤。     

基于ICEM CFD与ANSYS FLUENT的热力射流喷嘴流场分析

为了解喷嘴的内部结构对射流流场的影响,为选择合适的射流喷嘴提供依据,以锥形和锥直形喷嘴两种典型喷嘴为研究对象,根据计算流体力学（CFD）的基本理论,综合运用ICEM CFD网格划分与ANSYS FLUENT流体分析软件对锥形和锥直形喷嘴的射流流场进行分析。结果表明：在相同初始条件下,锥形喷嘴具有较大的出口速度,变化剧烈,射流的等速核长度较大;锥直形喷嘴的速度变化平稳,短管内由于颈缩现象易产生负压。通过试验,再次验证了仿真结果。     

Comparison on grain refinement efficiency of peritectic and eutectic alloying elements on pure aluminium

The work investigated the grain refining efficiency of peritectic forming solutes as well as eutectic solutes on pure Al. Significant grain refinement for peritectic and small refinement for the eutectic elements were achieved and the mechanisms of refinement were studied. In order to investigate the grain structure and solidification phenomena for each set of alloys, a TP-1 test, as well as thermal analysis, was performed and back scattered images were used to analyze the phases that may contribute to the grain refinement. It appears that the significant grain refinement of peritectic elements is due to the formation of in-situ properitectic particles and their appropriate constitutional undercooling. The results suggest that the availability of potent nuclei and exogenous particles play major roles in the grain refinement efficiency. However, in the case of eutectic elements only segregation power contributes to refinement whilst the availability of potent nuclei is of paramount importance.     

Modeling of the mechanical alloying process

Two programs have been developed to compute the dimensional and property changes that occur with repetitive impacts during the mechanical alloying process. The more sophisticated of the programs also maintains a running count of the fractions of particles present and from this calculates a population distribution. The programs predict powder particle size and shape changes in accord with the accepted stages of powder development during mechanical alloying of ductile species. They also predict hardness and lamellar thickness changes with processing, again with reasonable agreement with experimental results. The benefits of these predictions are twofold. First, they offer support of the model (and thereby give insight into the possible “actual” happenings of mechanical alloying) and hence allow refinement and calibration of the myriad aspects of the model. Second, they provide a vehicle for establishing control over the dimensions and properties of the output powders used for consolidation, thereby facilitating optimization of the consolidation process.     

临床试验机构研究者培训的标准操作规程

合格的研究者是保证临床试验质量的关键。临床试验机构对研究者的培训, 是研究者获得参加其所承担试验项目资格的必备条件。本操作规程是依据GCP 以及我院对研究者培训的实践制订的。内容包括制定培训计划, 研究者的岗位培训, 临床试验项目开始前的研究者培训, 培训原则, 培训技巧,培训评估, 培训者资格审定, 以及文件和档案的建立等。     

工程设备图形化管理系统的程序设计

介绍工程设备图形化数据库管理系统设计的一般方法和技术，分析和实施将设备对象作为图形对象处理时的程序设计技术，重点叙述图形对象与数据库关联的面向对象的程序设计方法。     

车活塞销双端面自动机床

介绍一种先进的、专门用于车活塞销两端面及倒内外角的全自动机床，扼要讨论了该机床的性能和工作过程，液压及电气系统的工作原理，和主要部件的结构特点及混凝土－钢板焊接车身的应用。     

液态金属电磁离心凝固的力场分析

运用磁流体动力学原理，对在稳恒磁场中高速旋转的液态金属凝固时的受力状态进行了理论解析，结果表明在电磁力场、离心力场和重力场共同作用下，旋转液态金属中受到大小周期变化的径向压力和切向分力，后者起电磁搅拌作用，是细化电磁离心凝固组织的根本原因．     

焊接接头表面改性的研究进展

概述了高能喷丸、表面机械研磨处理、超音速微粒轰击、超声冲击、激光冲击改性等表面改性方法的基本原理,重点分析了其对不同材料焊接接头表面进行改性的效果。这些改性方法可以细化焊接接头表面的晶粒,甚至使晶粒尺寸达到纳米级;提高焊接接头表面的显微硬度,从而提高焊接构件的强度;消除接头处的残余拉应力,使拉应力转变为残余压应力,从而抑制焊接接头裂纹源的产生,提高焊接接头的抗疲劳断裂能力,进一步提高焊接构件的寿命。了解了现有表面改性处理方法应用的领域范围及其优缺点,并对焊接接头表面改性处理方法的发展及研究方向进行了展望。