逆变弧焊电源中变压器的偏磁与防护

分析了全桥式逆变孤焊电源中变压器产生偏磁的原因及危害；阐述了在变压器一次侧串联电容或设置自动纠偏电路等防止偏磁的原理和方法。     

Nanocrystallization of Pd74Si18Au8 metallic glass

The crystallization process of Pd₇₄Si₁₈Au₈ amorphous alloy has been investigated by transmission electron microscopy, small angle X-ray scattering and three-dimensional atom probe techniques. Although literature suggests that the alloy decomposes into two glassy phases prior to the crystallization, we found that the crystallization occurs directly from a single amorphous phase by the primary crystallization of fcc Pd–Au solid solution, followed by the polymorphous crystallization of the remaining amorphous phase to a Pd₃Si phase.     

基于小波分析仪的CO2焊机波形分析

对焊接过程中的电信号进行小波滤波处理后，可以在消去信号中噪声的同时．保持电信号的特征形状不失真。采用自行研制的焊接电弧动态小波分析仪。对2台IGBT逆变焊接电源的焊接过程进行了测试分析．为焊接电源检测和工艺评判提供了一个有效的途径。对比分析结果表明：提高电压恢复率、各理增加短路过渡电流上升率和短路峰值电流，能够有效提高焊接电源的动态性能，改善焊接工艺质量。     

贝氏体相变特点的研究

研究贝氏体相变的特点，弄清贝氏体相变反应与共析分解的区别极为重要。本文应用QUANTA--400环扫电镜和JEM-2010高分辨电镜观察了多种钢的珠光体和贝氏体组织形貌和亚结构。综合以往的研究资料，从表象到本质上分析了贝氏体相变的特征，阐述了贝氏体相变与共析分解的区别。认为：贝氏体相变具有过渡性特征，贝氏体相变绝非共析分解。有的学者将贝氏体相变说成是共析分解的延续，那是不正确的。从贝氏体的物理本质出发，提出了钢中的珠光体、贝氏体、共析分解、钢中贝氏体相变等重要概念的新定义。     

不同应力状态下铝合金变形及损伤机理的研究

利用改装的Arcan夹具对铝合金（6063）的蝶形试样进行0°，30°，45°，60°，90°的拉伸及拉伸卸载试验，研究了铝合金在不同应力状态下变形及损伤机理。结果表明：铝合金在不同应力状态下的工程应力一应变曲线明显不同。0°加载时，在蝶形中心产生微孔洞，微孔洞之间剪切，从而产生了微裂纹。随着微裂纹的扩展、连接导致试样断裂。随着试样中三轴应力度的减小，在蝶形试样中心的剪切应力不断增大，同时在蝶形试样中的剪切变形带越来越集中。显微裂纹首先在剪切带中产生，随着微裂纹的扩展导致试样的断裂。90°拉伸时，在蝶形中心形成明显的剪切变形带。90°加载时，在试样中产生的剪切带是形变剪切带而非相变剪切带。利用有限元软件ABAQUS对不同角度拉伸试验进行模拟，从而得出了不同应力状态下的塑性区的形状和大小。     

Low-Cost,High-Speed Domain Refinement without Damage to Insulative Coatings

Rolling large- diameter hardened steel balls over the surface of high- permeability grain- oriented electri-cal steel allows lines of plastic deformation to be laid down. Choice of proper Young’s modulus and ball diameter enables artificial grain boundaries to be created, producing appropriate domain refinement and loss reduction.     

钼精矿供应紧张支撑钼市场

介绍了2006年上半年国际、国内钼市场的产量、供需平衡及进出口情况。西方世界钼产量平稳，钼价格呈现出上涨趋势。西方世界钼铁平均价格1月份为53．5～55．8美元／kg，6月份为58．71～60．07美元/kg，上涨9．72％；中国产钼铁在鹿特丹仓库现货价格1月份为50．99～53．70美元／kg，6月份为58．51～60．03美元／kg，上涨14．74％。分析了上半年国际、国内钼市场的形势，预测下半年国际钼市场钼精矿供应仍将紧张，副产钼供应平缓，因此下半年的钼市场将得到支撑。     

Thermophysical properties of a Ti–44%Al–8%Nb–1%B alloy in the solid and molten states

The families of titanium aluminide intermetallic alloys have attractive high temperature mechanical properties which make them potential candidate materials for a wide range of applications, particularly in the aeronautic and automobile sectors. The development of appropriate manufacturing techniques is an essential stage in the engineering exploitation of these materials, e.g., Induction Skull Melting is one of the techniques which needs to be optimised for the casting of titanium aluminides. Research is underway to develop a computer model of this process but data are required for the key thermophysical properties. Pulse-heating techniques have been used to measure properties for the Ti–44Al–8Nb–1B system. Rectangular samples have been prepared and are resistively heated as part of a fast capacitor discharge circuit. Time-resolved measurements with sub-μs resolution of currents through the specimen were made with a Pearson probe current monitor using the induction principle. Voltages across the specimen were determined with knife-edge contacts and voltage dividers, and radiance temperatures of the sample were measured with a pyrometer. These measurements allow the calculation of specific heat and dependencies between enthalpy, electrical resistivity and temperature of the alloy up into the liquid phase. Data for thermal diffusivity have been obtained by using the Wiedeman–Franz relation. The results are compared with those obtained using DSC and the four-probe method to measure the temperature dependence of the resistivity.     

The effect of plasma spraying power on the structure and mechanical properties of hydroxyapatite deposited onto carbon/carbon composites

This paper deals with the effect of plasma spraying power on hydroxyapatite (HA) coatings on carbon/carbon composites (C/C composites). The microstructure and phase composition of the as-sprayed coatings have been examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The shear strength of the HA coatings–C/C substrates was detected on a RGD-5 tensile testing machine. Results indicate that the melting extent and the shear strength of the coatings were evidently improved with the increasing of spraying power. Moreover, the amount of decomposed phases is increased and the content of crystalline HA of coatings was slightly changed. Observation of fracture surfaces shows that carbon fiber bundles can bond well with HA coatings using 40 kW spraying power.     

纳米晶镁铝水滑石／聚乙烯复合阻燃料的制备

采用共混法制备聚乙烯／镁铝水滑石纳米复合材料。XRD、SEM、TEM和性能测试表明：镁铝水滑石纳米晶体分散在聚乙烯基体中，且有少部分发生插层；阴离子表面活性剂对水滑石的处理效果要优于偶联剂；pH值对处理效果有一定影响；镁铝水滑石阻燃剂填充聚乙烯体系阻燃效果，要优于填充A1（OH）3阻燃剂。