脉冲电流对金属材料的作用及其研究进展

综合评述了脉冲电流作用下的金属的凝固过程，金属的电致塑性效应，非晶结构变化和纳米晶化，金属材料的仿生恢复和愈合等方面的最近进展，着重介绍了脉冲电流在材料制备，加工和使用中的应用，同时提出了利用瞬态能量输入进行材料仿生复效处理这一新途径。     

直接晶化法制备块状纳米材料的探索──Ⅰ脉冲电流作用下无序金属介质的成核理论

利用经典热力学和连续介质电动力学理论计算了脉冲电流作用下无序介质（包括金属熔体和非晶态金属）的成核率．结果表明：对于无序介质的晶化过程，随脉冲电流密度增加，形核率成指数增大；超短时脉冲有可能使熔体直接冷凝成大块纳米晶材料，并能限制已经形成的纳米晶粒的长大．     

EXPLORATION ON THE FABRICATION OF BULK NANOCRYSTALLINE MATERIALS BY DIRECT-NANOCRYSTALLIZING METHOD Ⅰ. Nucleation in Disordered Metallic Media by Electropulsing

利用经典热力学和连续介质电动力学理论计算了脉冲电流信息处理作用下无序介质（包括金属熔体和非晶态金属）的成核率。结果表明：对于无序介质的晶化过程，随脉冲电流密度增加。形核率成指数增大；超短时脉冲有可能使熔体直接冷凝成大块纳米晶材料，并能限制已经形成的纲米晶粒的长大。     

脉冲电流烧结技术的研究进展

脉冲电流烧结（Ｐｕｌｓｅ ｅｌｅｃｔｒｉｃ ｃｕｒｒｅｎｔ ｓｉｎｔｅｒｉｎｇ，ＰＥＣＳ）是材料科学领域开发出的一种新型快速烧结技术，已广泛应用于金属与合金、结构陶瓷、氧化物超时体、复合材料、热电材料、离电材料、高分子材料以及功能梯度材料的制备；检验结果，对脉冲电流烧结非导电性粉体的烧结过程和机理，提出自己的观点。     

脉冲电流烧结机理研究

脉冲电流烧结(Pulse electric current sintering,PECS)是材料科学领域开发出的一种新型快速烧结技术,已广泛应用于金属与合金、结构陶瓷、氧化物超导体、复合材料、热电材料、高分子材料以及功能梯度材料的制备.本文在介绍脉冲电流烧结装置与研究进展的基础上,研究PECS烧结条件对氧化铝粉末致密化及显微结构的影响,以探讨脉冲电流烧结机理.     

脉冲电流烧结机理的研究进展

脉冲电流烧结（Ｐｕｌｓｅ ｅｌｅｃｔｒｉｃ ｃｕｒｒｅｎｔ ｓｉｎｔｅｒｉｎｇ,ＰＥＣＳ）是材料科学领域开发出的一种新型快速烧结技术,已广泛应用于金属与合金、结构陶瓷、氧化物超导体、复合材料、热电材料、高分子材料以及功能梯度材料的制备．本文简介脉冲电流烧结特征,结合ＰＥＣＳ烧结条件对铜粉末和氧化铝粉体致密化及显微结构影响的实验证据,就脉冲电流烧结过程和机理进行探讨．     

脉冲电流条件下Ni箔流动应力及其尺寸效应的神经网络模型

目的揭示脉冲电流对金属箔材室温流动应力及其尺寸效应的影响规律,构建脉冲条件下Ni箔室温塑性流动的本构模型。方法采用单向拉伸试验,测试不同试样尺寸的Ni箔在不同电流密度条件下的单向拉伸性能。根据本构方程的输入、输出参数,设计BP神经网络结构,并利用试验数据对其进行训练及预测精度检验。结果单向拉伸试验结果表明,箔材厚度与晶粒尺寸之比及变形过程中引入的脉冲电流均会对材料的流动应力产生显著影响,且其影响规律高度复杂。脉冲电流条件下,构建的金属箔材流动应力尺寸效应神经网络模型,其预测相对误差控制在6%以内,相关系数R达到0.99。结论该神经网络模型准确描述了脉冲电流条件下金属Ni箔流动应力尺寸效应,为该材料塑性变形过程分析及合理制定工艺参数奠定了理论基础。     

结构仿生材料的研究进展

自然界中生物体的优异结构和特性给人类研究材料带来了灵感和启发.借鉴这些生物体的优秀结构特征是结构仿生材料的主要设计思想和方法.重点阐述了仿生增韧陶瓷材料、仿生粘附材料、仿生减阻材料、仿生减振材料和仿生系统应用在设计和制备方面的研究进展,并展望了结构仿生材料的发展前景,强调了多学科协作的重要性.     

在脉冲电流或脉冲磁场作用下LY12合金的凝固组织

在LY12铝合金凝固过程中施加脉冲电流或脉冲磁场，研究脉冲电流或脉冲磁场对这种合金凝固组织的影响。结果表明，脉冲电流和脉冲磁场均可使晶粒明显细化，等轴化，在脉冲电磁艇下金属凝固组织的晶粒细化机制为：在脉冲电磁场的作用下剧烈的强迫对流促进晶粒从型壁上游离，大大增加金属熔体的形核率，导致晶粒细化；温度相对均匀使得游得的晶粒得以保存下来，抑制了晶粒在某个方向上的优先,从而抑制了树枝晶的形成。     

脉冲电流对7475铝合金超塑性变形力学性能的影响

旨在确定脉冲电流对7475铝合金超塑性变形的宏观力学性能的影响，以探求脉冲电流对降低7475铝合金超塑性变形条件的可能性，实验结果表明，施加脉冲电流后，合金的延伸率和反变敏感性指数都有很大提高，对于普通超塑性变形所能达到的延伸率，施加脉冲电流后在降低变形温度和提高变形速度的情况下仍能达到，电流对超塑性变形金属内物质迁移的促进应是产生这一现象的原因。     

Microstructure and Temperature Distribution in ZnAl2O4 Sintered Body by Pulse Electric Current

Microstructure of reaction sintering of ZnAl2O4 at 1500℃ by hot-pressing(HP) and pulse electric current was investigated. The results indicated that the existed cracks in sintered body were caused by structure mismatch. It is the evidence that periodical temperature field existed during pulse electric current sintering of nonconductive materials.The distance between high temperature areas was related to die diameter.     

仿生层状复合材料研究概况

从仿生的角度介绍了仿生复合材料尤其是层状复合材料的设计原理，制备方法，主要研究内容和现状。指出了仿生复合材料的应用前景和今后的发展方向。     

Biomimetic and Bioinspired Synthesis of Nanomaterials/Nanostructures

In recent years, due to its unparalleled advantages, the biomimetic and bioinspired synthesis of nanomaterials/nanostructures has drawn increasing interest and attention. Generally, biomimetic synthesis can be conducted either by mimicking the functions of natural materials/structures or by mimicking the biological processes that organisms employ to produce substances or materials. Biomimetic synthesis is therefore divided here into “functional biomimetic synthesis” and “process biomimetic synthesis”. Process biomimetic synthesis is the focus of this review. First, the above two terms are defined and their relationship is discussed. Next different levels of biological processes that can be used for process biomimetic synthesis are compiled. Then the current progress of process biomimetic synthesis is systematically summarized and reviewed from the following five perspectives: i) elementary biomimetic system via biomass templates, ii) high‐level biomimetic system via soft/hard‐combined films, iii) intelligent biomimetic systems via liquid membranes, iv) living‐organism biomimetic systems, and v) macromolecular bioinspired systems. Moreover, for these five biomimetic systems, the synthesis procedures, basic principles, and relationships are discussed, and the challenges that are encountered and directions for further development are considered.     

Electric pulse current effect on stress-strain state in the notch vicinity in a cantilever beam under cyclic bending

Calculation results of the thermal effect assessment induced by electric pulse current on stress variation in the edge notch vicinity in a metal cantilever beam under cyclic bending are presented. The results obtained indicate that thermal action of electric pulse current diminishes the level of the maximal tensile stresses in the notch vicinity, while the cyclic stress range remains constant during further loading. The preliminary uniform heating enhances the electric pulse current action. Under plain stress state loading conditions, the electric pulse current effect is much less pronounced, as compared to plain strain state loading conditions.     

The Ultimate State of Structural Alloys for Superconducting Electromagnetic System of Thermonuclear Reactor

The analysis of service conditions for the elements of a superconducting electromagnetic system of thermonuclear reactor is performed. Based on the study of the peculiarities of deformation and fracture of alloys subjected to an electric pulse current and cryogenic temperatures, criteria for the ultimate state of the materials are established and the methods for their determination are outlined.     

脉冲电流对45钢损伤的恢复作用

研究了脉冲电流对４５钢淬火裂纹的修复作用。结果表明,脉冲电流显著提高有裂纹的马氏体材料的强度和塑性,但硬度降低不多,脉冲电流处理后,裂纹周围的组织发生了显著变化。对裂纹钝化有利,探讨了裂纹在脉冲电流作用下的愈合效应,说明电流,热效应及热压应力可能是诱发该效应的主要因素。     

Bio-inspired study of structural materials

The terminology of materials study inspired by biological systems or phenomena is analyzed at first. It is pointed that the term “bio-inspired” may be better than the terms “bionic” or “biomimetic”, since the former is relatively easy to be accepted. The new trends of bio-inspired study of structural materials are analyzed in short. Some progress in bio-inspired design and processing of materials in this institute (IMRCAS) are summarized briefly in this talk, such as biomimetic design of worst bonding interface for composites; dumbell-like whiskers simulating animal bone; fractal tree reinforcement by mimicry of branched roots in soil; etc.The possibility of modification and recovery of materials by nonequilibrium bio-inspired treatment are further explored, including the nonequilibrium process under transient heating, dissipative structure and self-organization process of open system, inspiration by living process, influence of high intensive electropulsing on the working life of materials, a possible way of fatigue recovery of materials and the healing effect of electropulsing in metals. Some tentative practice in biomaterial modification are also studied such as the reformed bamboo reinforced aluminium laminates, etc. A discussion on the methodology of bio-inspired study of materials consists briefly in the last part of the talk.     

仿生结构复合材料研究现状

综述了贝壳珍珠层、蛛丝结构、竹材外密内疏结构、植物的根部网状结构以及骨骼哑铃型结构等天然生物材料的结构特征及其相应的仿生材料近年来的研究进展,展望了结构仿生材料的应用前景.认为应对现有生物体的结构特征与其性能的相关性进行进一步的研究,从材料科学角度研究它们的规律,进行仿生设计,以推动仿生材料学的发展.