Preparation of transmission electron microscopy cross-section specimens of crack tips using focused ion beam milling

The preparation of transmission electron microscope (TEM) thin foil specimens from metal alloys containing cracks is usually thwarted by the difficulty in preventing preferential erosion of material along the flanks and at the tips of cracks. Recent developments in focused ion beam (FIB) micromachining methods have the potential to overcome this inherent problem. In this article we describe the development of new procedures, one using FIB alone and the other using a combination of FIB with more conventional ion milling to generate TEM specimens that largely retain the microstructural information at stress corrosion cracks in austentic alloys. Examples of corrosion product phase identification and interfacial segregation are included to verify that detailed information is not destroyed by ion bombardment during specimen preparation.     

The Atmospheric Scanning Electron Microscope with open sample space observes dynamic phenomena in liquid or gas

Although conventional electron microscopy (EM) requires samples to be in vacuum, most chemical and physical reactions occur in liquid or gas. The Atmospheric Scanning Electron Microscope (ASEM) can observe dynamic phenomena in liquid or gas under atmospheric pressure in real time. An electron-permeable window made of pressure-resistant 100 nm-thick silicon nitride (SiN) film, set into the bottom of the open ASEM sample dish, allows an electron beam to be projected from underneath the sample. A detector positioned below captures backscattered electrons. Using the ASEM, we observed the radiation-induced self-organization process of particles, as well as phenomena accompanying volume change, including evaporation-induced crystallization. Using the electrochemical ASEM dish, we observed tree-like electrochemical depositions on the cathode. In silver nitrate solution, we observed silver depositions near the cathode forming incidental internal voids. The heated ASEM dish allowed observation of patterns of contrast in melting and solidifying solder. Finally, to demonstrate its applicability for monitoring and control of industrial processes, silver paste and solder paste were examined at high throughput. High resolution, imaging speed, flexibility, adaptability, and ease of use facilitate the observation of previously difficult-to-image phenomena, and make the ASEM applicable to various fields.     

平面齿双曲线锥齿轮的运动学分析

提出了1种平面齿双曲线锥齿轮啮合的运动学公式，利用此公式去比较双曲线锥齿轮啮合面与其他形式啮合面的最大赫兹接触应力，得出平面齿双曲线锥齿轮传动比其他形式齿轮传动能传递更大功率。     

液力变矩器-机械无级变速器自动变速汽车综合控制策略研究

针对采用液力变矩器作为汽车起步和低速行驶时的调速装置,金属带无级变速传动为高速行驶时调速装置的双状态无级自动变速汽车,在液力变矩器台架试验的基础上,建立了双状态无级自动变速汽车的动力学仿真模型和金属带无级变速传动系统的综合控制策略,分析了分段加速行驶过程中,汽车液力变矩器和金属带无级变速器速比的变化规律,为开发设计双状态无级自动变速汽车提供理论依据。     

数控转塔冲床主传动的发展

对数控转塔冲床主传动部件的发展历程进行了综述,并分析了三种传动方式的优劣。提出将交流伺服控制系统用于数控转塔冲床,采用大规模集成化技术及智能化功率模块,实现对交流伺服的位置环、速度环和电流环的全数字化控制,提高冲床的加工精度及效率。     

车辆动力传动系的耦合与匹配研究

阐述产品设计耦舍与匹配的概念，提出了车辆动力传动系统匹配的基本内容。包括结构布置、性能、控制和强刚度等4类匹配。以栽重汽车传动系各挡传动比分配为应用示例，建立优化数学模型并求解，得出比原车性能更好的传动比分配结果。     

STRATEGIES FOR SOLVING KEY PROBLEMS IN RESEARCH AND DEVELOPMENT OF AUTOMOTIVE CONTINUOUSLY VARIABLE TRANSMISSION

ＳＴＲＡＴＥＧＩＥＳＦＯＲＳＯＬＶＩＮＧＫＥＹＰＲＯＢＬＥＭＳＩＮＲＥＳＥＡＲＣＨＡＮＤＤＥＶＥＬＯＰＭＥＮＴＯＦＡＵＴＯＭＯＴＩＶＥＣＯＮＴＩＮＵＯＵＳＬＹＶＡＲＩＡＢＬＥＴＲＡＮＳＭＩＳＳＩＯＮ①ＨｕａｎｇＸｉａｎｇｄｏｎｇＹａｎｙｕＬｉｎＢｉｎ...     

Dislocation identification and in situ straining in the spinodal Fe30Ni20Mn25Al25 alloy

Dislocations in the spinodal alloy Fe(30)Ni(20)Mn(25)Al(25), which is composed of alternating BCC and B2 (ordered BCC) phases, have been investigated using weak-beam transmission electron microscopy (TEM). The alloy was compressed at room temperature in an as-hot-extruded state to strains of approximately 3% for post-mortem dislocation analysis. Dislocations with a/2<111> Burgers vectors were found to glide in pairs on both {110} and {112} slip planes. TEM in situ straining experiments were also performed on both the as-extruded alloy and an arc-melted alloy. The in situ straining observations confirmed that dislocations were able to pass between both spinodal phases. Partial dislocation separations were relatively wide in the BCC phase and narrow in the B2 phase. Dislocation glide, as opposed to twinning (both of which have been observed in other BCC-based spinodals), was also found to be the only room temperature deformation mechanism.     

新型牵引-制动型液力变矩减速器原始特性计算

液力变矩器的原始特性能够确切地表示液力变矩器的基本性能,而且通过计算方法可以获得几何相似的系列变矩器的外特性或通用特性。对设计牵引-制动型液力变矩减速器具有一定的指导意义。这里基于束流理论建立了某新型牵引-制动型液力变矩器原始特性参数的计算数学模型。得出了该牵引-制动型液力变矩减速器的变矩工矿原始特性参数曲线。