Ir和IrRh40合金热电偶丝的显微组织和力学性能研究

采用光学显微镜(OM)、扫描电镜(SEM)和力学试验机等测试手段,对Φ0.5 mm的加工态Ir丝和IrRh40合金丝的金相组织、断口形貌和力学性能进行了分析。结果表明:Rh能明显细化Ir合金的显微组织,IrRh40合金比纯Ir具有更细的晶粒,但Rh并不能提高Ir合金的强度和延伸率,Ir丝的平均抗拉强度为2103 MPa,IrRh40合金丝的平均抗拉强度为1765 MPa,2种合金的延伸率为8%~10%;Ir丝和IrRh40合金丝的拉伸断裂方式主要为穿晶断裂,在断裂之前存在明显的"颈缩"现象。     

Influence of Mg Contents on Aging Precipitation Behavior of Al-3.5Cu-xMg Alloy

The influence of Mg content on the microstructures and mechanical properties at room temperatures of Al-3.5Cu-(0.71-1.81)Mg alloys was studied.Precipitation phases in the alloys were identified by TEM and HRTEM.The results show that when Mg contents increase from 0.71 to 1.81 wt%,the precipitates are transformed from S,S″,Ω,and θ' phases to Sand S′phases,and Ω phase is first observed in Al-3.48Cu-0.71 Mg alloy with Cu/Mg mass ratio of 5 during the conventional aging heat treatment(190 ℃/12 h).Regard to aging hardness effect of the tested alloys,the hardness of the alloys improves with the increase of Mg content,but the increases become slow when Mg content is greater than 1.35 wt%.     

Precipitation behavior in Al-Zn-Mg-Cu alloy after direct quenching

The precipitation behavior in an Al-6.8Zn-1.9Mg-1.0Cu-0.12Zr alloy after direct quenching from solution heat treatment temperature of 470 °C to 205–355 °C was investigated by means of hardness tests, electrical conductivity tests, and transmission electron microscopy. At temperatures below 265 °C, the hardness increased gradually to a peak value and then decreased rapidly with time. At 265 °C, the hardness was almost unchanged within the initial 2000 s and then decreased gradually. At higher temperatures, the hardness decreased slowly with time. The electrical conductivity started to increase after a certain period of time and then tended to maintain a constant value at all temperatures. Microstructure examination indicated heterogeneous precipitation of the η phase at grain boundaries and inside grains during holding at 205 °C and 325 °C. Based on the electrical conductivity data, the precipitation kinetics could be described quite well by the Johnson-Mehl-Avrami-Komolgorov relationship with a n value varying between 0.78 and 1.33. The activation energy was estimated to be about 44.9 kJ/mol, which is close to that expected for a dislocation diffusion mechanism. Time-temperature-transformation diagrams were constructed and the nose temperature ranged from 295 °C to 325 °C.     

Isothermal Section of Al-Si-Ce Ternary System at 1073 K

The phase equilibria in the Al-Si-Ce ternary system at 1073 K is investigated by means of x-ray diffraction and scanning electron microscope coupled with energy dispersive spectroscopy. There exist 12 three-phase regions exist in this system and one can be deduced. One ternary compound T (Ce(Al _x Si_1?x )₂) found in the isothermal section at 1073 K has the LaPtSi structure with a lattice parameter a = 0.4242 nm which composition span ranges from 32.1-47.8 at.%Al, 17.9-33.7 at.% Si, 33.4-34.0 at.% Ce. The maximum solubility of Al (in at.%) in CeSi_2?α, CeSi, Ce₅Si₄, Ce₃Si₂ and Ce₅Si₃ at 1073 K is 29.3, 23.8, 2.8, 13.6 and 6.5 respectively, and the maximum solubility of Si (in at.%) in Al₄Ce, Al₃Ce, Al₂Ce and AlCe at 1073 K is 1.4, 1.7, 1.8 and 2.1 respectively.     

采用层次分析法（AHP）综合评价轧制油（Ⅱ）：评价结果与分析

在国内外首次引入层次分析法（AHP）对轧制油进行评价和综合排序，解决了由金属加工用润滑剂及油品及工艺润滑性能指标较多，选择最佳润滑剂困难的问题；而且工业应用表明AHP法是非常有序的。本文的第I部分已介绍了层次分析法及其求解步骤∧［1］。第Ⅱ部分则应用层次分析法对轧制油进行评价和综合排序。     

基于GIS技术的湖南省水环境信息系统设计

随着我国水资源保护工作的不断开展,应用GIS系统将实现水行政主管部门对水资源的形象、高效和直观管理。设计以ARCINFO为平台,采用C/S和B/S相结合的混合体系结构对系统进行开发和设计。文章主要介绍了系统构成和系统功能。     

2000t快锻机的在线监测与维护

结合生产实际，介绍２０００ｔ快锻机液压传动系统的组成和工作情况，并从信号检测，计算机数据采集和处理等方面介绍快锻机在线监测的设计和使用情况。最后从信息构成、知识综合和量化分析讨论监测技术在设备中的作用     

钽丝的织构和再结晶行为研究

研究了变形钽丝在不同温度下退火后的织构演变和再结晶行为，发现1360℃退火后钽丝初次再结晶基本完成；1500℃退火后，钽丝中发生了二次再结晶，晶粒异常粗大。提出了拉拔钽丝的再结晶织构模型。     

光纤轴角传感器设计

基于反射原理的光纤角度传感特性，利用输入光纤光束照射可以绕偏心轴转动柱型反射面，其反射光斑在入射光纤端平面所在的接收平面上呈近椭圆状。位于入射光纤两侧的接收光纤耦合光斑能量。接收面上光斑的长短轴、中心、面积都是轴角的函数。以接收光功率与入射光功率比映射轴角曲线关系具有高的共模抑制比。