镍基双合金扩散偶的拉伸性能研究

采用热等静压(HIP)扩散连接工艺,获得了镍基单晶高温合金与粉末高温合金的扩散偶。研究了热等静压和热处理工艺对扩散偶的组织和拉伸性能的影响。结果表明,不同温度热等静压的扩散偶均实现了冶金结合,瞬时拉伸断口位置处于DD402侧,断裂面为{111}滑移面。随着HIP温度升高,DD402母材的γ′相粒子粗化,FGH95粉末合金母材的再结晶晶粒长大;1 166℃HIP扩散偶热处理后,FGH95粉末合金的γ′相由晶界大尺寸γ′相、晶粒内中等尺寸的和细小的γ′相组成。扩散偶试样的650℃抗拉强度受HIP温度影响小,而屈服强度随着HIP温度升高而降低。     

氧化工艺对Ag-ZnO触头材料性能的影响

论述了研制Ag-ZnO触头材料的两种氧化工艺,即粉末预氧化和压块预氧化,重点讨论了氧化工艺和氧化时间对材料性能的影响,采用预氧化法与复压工艺研制Ag-ZnO触头材料,可提高材料的密度,改善该材料的物理机械性能。     

合金粉末预氧化法制备Ag-SnO2-Y2O3电接触材料的研究

Ag-SnO2是各国电接触材料研究人员近年来新开发的一种无镉新型触头材料,它具有较好的导电导热性,优良的耐热性、抗电弧烧蚀性和抗熔焊性,是目前代替Ag-CdO的最理想材料。本文通过合金粉末预氧化法、复合粉体改性处理技术来制备Ag-SnO2-Y2O3电接触材料,添加稀土后合金粉末容易氧化,氧化粉体经改性处理后可有效改善氧化物颗粒与银基体间的润湿性、改善材料的后续加工性能,并且所制备的Ag-SnO2-Y2O3材料密度高、组织均匀、不存在宏观偏析,SnO2和Y2O3颗粒在材料中弥散均匀分布。     

Ag-ZnO触头材料制备工艺对其组织和性能的影响

讨论了Ag-ZnO触头材料的三种制备工艺——粉末预氧化法、压块预氧化法和机械混合法。当采用粉末预氧化工艺时,重点讨论了烧结温度和烧结时间对于材料组织和性能的影响。采用预氧化法制备Ag-ZnO触头材料,可提高材料密度,改善氧化物的分布状况,从而改善材料的组织和物理性能。     

Ag-Sn-In合金粉末高压氧化机制的研究

采用雾化法制备了Ag-8 Sn-3.7 In(%,质量分数)合金粉末。分别研究了氧气压力、氧化温度及氧化时间对Ag-8 Sn-3.7 In合金粉末氧化行为的影响规律。系统地分析了Ag-8 Sn-3.7 In合金粉末氧化前后的物相组成、粉末粒度、表面形貌及表面成分。研究结果表明:Ag·SnO_2·In_2O_3合金粉末高压氧化条件中,温度起决定性的作用,选择合适的氧化温度是该氧化工艺的关键。当温度不够高时,需要长时间才能达到完全氧化。氧气压力可以加快氧化的进程,当氧气压力达到0.75 MPa以后,增大氧气压力,意义不大。对三种不同氧化工艺得到的Ag·SnO_2·In_2O_3合金粉末进行成分分析,在氧化完全的条件下,氧化温度越高,其表面偏析现象越低。在Ag-Sn-In合金粉末高压氧化过程中,氧向合金粉末内部扩散, Sn和In向粉末表面扩散,与O_2反应分别形成SnO_2和In_2O_3,聚集在颗粒表面的SnO_2相和In_2O_3相在表面反应,形成表面2In_2O_3·3SnO_2壳层,阻碍了Sn原子的进一步扩散。对于Ag-8 Sn-3.7 In(%,质量分数)合金粉末,较好的氧化参数为:氧化温度500℃,氧气压力0.75 MPa,氧化时间2 h。     

Nd系磁体原料粉的制取方法

Nd系磁体原料粉的制取方法有还原扩散法和合金法两种,其后者又可分为快淬法和粉末法。还原扩散法与合金法不同的是合金法必须把氧化钕(Nd_2O_3)转化成金属后才能作为原料使用,而还原扩散法则是直接以氧化物(Nd_2O_3)的形式使用,既简化了工艺流     

Fe-1.0Cu-2.0Ni-0.55Mo扩散型合金钢粉的研制

本文针对莱粉公司生产的Fe-1.0Cu-2.0Ni-0.55Mo扩散型合金钢粉的生产工艺、粉末性能及其烧结件性能进行了研究。结果表明,采用本工艺生产的扩散型合金钢粉基本保持了基体粉末压缩性高、流动性好的特点,可获得高的压坯密度和烧结体密度;合金粉末损失少且分布均匀,制件尺寸精度高、机械性能稳定;扩散合金化效果好,制件具有较高的硬度和抗拉强度。同时,该生产工艺减少了合金粉末(细粉)的损失和飞扬,生产环境得以很大改善。     

镍铬合金包覆粉末的制取

本文研究了用湿法冶金氢还原技术与固相热扩散法相结合制取镍铬合金包覆粉末的工艺。探讨了热扩散温度、时间、活化剂、原料铬粉、核心粉材质等对复合粉末性能的影响。测定了用不同工艺条件制备的合全复合粉的物化特性及复合粉在空气中的高温抗氧化性能。     

扩散温度对车用Al_2O_3/Sn0.3Ag0.7Cu合金粉末组织及物理性能的影响

对以Al_2O_3作为增强体的Sn0.3Ag0.7Cu合金粉末进行扩散强化处理,研究扩散温度对其组织及物理性能的影响。结果表明:将Sn0.3Ag0.7Cu合金粉末升温到700℃再进行扩散强化,压坯的尺寸偏差为±0.04 mm,尺寸均匀性较高,合金粉末具备良好的成形能力。扩散合金化温度升高至700℃实现Sn与Cu的完全固溶,得到的粉末颗粒内锡含量为8.6%～9.7%,合金粉末中形成了均匀分布状态的锡。在各温度下进行扩散强化处理得到的Sn0.3Ag0.7Cu合金粉末具有相近的流动能力与松装密度,表现出了优异的流动性。以700℃进行扩散强化得到的细小粉末,具备可控松装度与流动能力,表现出良好压缩特性。     

金属粉末还原中的冶金反应工程学探讨

就冶金反应工程学中的质量传输及化学反应在金属粉末还原过程中的应用进行了初步探讨。指出:气-固反应是常见的金属粉末还原反应之一;常用的还原设备,如管式电炉,可看成活塞流反应器,并用活塞流反应器的物质恒算方程来描述;气固间的对流传质可用舍伍德数、雷诺准数和施密特数的组合来表征,固相内气体扩散的质量通量是孔隙率、孔的曲折度、有效扩散系数和浓度梯度的函数,固相内的气固反应可用缩小的未反应核模型来描述;粉末物料的还原程度取决于固体内的气体扩散及气固反应,哪一个过程进行得最慢,则该过程就是全过程的控制环节。     

Contact precipitation of silver on copper powder

The processing characteristics of articles made from copper powder can be improved by alloying the copper powder with additions of silver (up to 0.2%). The simplest and most economical method is deposition of silver onto copper powder particles by contact exchange. We have studied the effect of different types of electrolytes (nitrate, pyrophosphate, sulfosalicylate, sulfite, ferricyanide, cyanide thiocyanate, and thiocyanate) on the kinetic characteristics of the electrode processes. We have done structural studies of copper powder alloyed with silver. We have determined the bulk (as-poured) density of the powders after cementation, and also the density, shrinkage, electrical resistance, and hardness of specimens prepared by the traditional procedure from the alloyed powders. In most of the studied systems, the cementation process occurs with diffusion control of the cathode reaction. However, this does not lead to visible formation of growths and dendrites of silver on the surface of the copper particles. According to x-ray phase analysis results, during cementation a solid solution of copper in silver is formed on the surface of the particles. After sintering the green compacts, the alloy is homogenized with formation of a solid solution of silver in copper. The nature of the electrolyte markedly affects the properties of the Cu−Ag material. In some cases, the hardness and electrical conductance of the specimens increase simultaneously. Technological and economic considerations lead to choosing cyanide thiocyanate electrolyte as the best for alloying copper powder with silver. Urals State Technical University; Institute of High-Temperature Electrochemistry, Urals Branch, Russian Academy of Sciences, Ekaterinburg. Translated from Poroshkovaya Metallurgiya, Nos. 7–8(408), pp. 22–29, July–August, 1999.     

气体雾化LaNi5型储氢合金粉末特性的研究

采用金相显微镜、扫描电镜、俄歇能谱探针、Ｘ射线衍射对气体雾化法制备的储氢合金粉末的物理特性、表面化学状态、显微组织结构进行了初步探讨，并将其与熔铸破碎法所制备的合金粉末相比较。结果表明：气体雾化法制备的储氢合金粉末氧含量低，呈球形无表面缺陷；物相组成为单一ＬａＮｉ５相；显微结构呈细小胞状晶和枝状晶组织。     

利用废弃银铜合金触点直接制备银铜双金属粉

研究了利用废弃银铜合金触点(Ag、Cu、Sn质量分数分别约为30%、60%和2%)直接制备银铜双金属粉的工艺。原料以硝酸溶解后,采用葡萄糖预还原和水合肼二次还原,在聚乙烯吡咯烷酮(PVP)的保护下制得了粒径在1μm左右类球形超细银铜双金属粉和超细铜粉。还原前加入尿素,控制反应温度在60℃温度下,加入抗氧化剂苯并三氮唑,均可防止铜粉的表面氧化,从而获得高质量的银铜双金属粉,银、铜的回收率达到99%以上。所得产品可再用于粉末冶金法制备银铜合金触点,或者直接用于制备电子浆料。该工艺可避免银、铜的分离过程,使废弃银、铜合金触点中银、铜的回收和深加工得到有效结合,从而实现节能减排的目标。     

Microstructures and Properties of Nanocrystalline NiFe Alloy With and Without Particulate TiC Reinforcement by Mechanical Alloying

In the current study, Ni₅₀Fe₅₀ alloy powders were prepared using a high-energy planetary ball mill. The effects of TiC addition (0, 5, 10, 20, and 30 wt pct) and milling time on the sequence of alloy formation, the microstructure, and microhardness of the product were studied. The structure of solid solution phase, the lattice parameter, lattice strain, and grain size were identified by X-ray diffraction analysis. The correlation between the apparent densities and the milling time is explained by the morphologic evolution of the powder particles occurring during the high-energy milling process. The powder morphology was examined using scanning electron microscopy. It was found that FCC γ (Fe–Ni) solid solution was formed after 10 hours of milling, and this time was reduced to 7 hours when TiC was added. Therefore, brittle particles (TiC) accelerate the milling process by increasing crystal defects leading to a shorter diffusion path. Observations of polished cross section showed uniform distribution of the reinforcement particles. The apparent density increases with the increasing TiC content. It was also found that the higher TiC amount leads to larger lattice parameter, higher internal strain, and lower grain size of the alloy.     

State of Ni–Cr–B–Si–Fe/WC coatings after plasma powder surfacing with nanopowder modifier

The structure and phase state and internal stress fields of plasma powder Ni–Cr–B–Si–Fe/WC surface coatings are compared in the presence and absence of a modifier: Al₂O₃ nanoparticles. PS-12NVK-01 powder alloy applied to a steel 20 substrate is studied by transmission diffraction electron microscopy of thin films, scanning electron microscopy, and X-ray structural and local X-ray spectral analysis. The phase composition of the alloy is determined; its defect structure and internal stress are studied. The structure of the material is analyzed before and after the introduction of Al₂O₃ nanopowder in the melt. Introducing the modifier reduces the grain size of the material; leads to the formation of tungsten carbide W₂C and the boride Fe₃Ni₃B in the carbide subsystem; and reduces the internal stress and scalar dislocation density.     

Properties Enhancement of an Eco-Friendly Electrical Contact Material by Silver Nanoparticles Addition

Silver-tin oxide electrical contact material with 10?wt pct stannic oxide and balance nanosized and micronsized silver was developed successfully. Stannic oxide particles chemically coated by a layer of silver nanospheres are homogeneously dispersed in a silver microcrystalline matrix made by chemical synthesis. The material processed by pressing-sintering-repressing exhibited enhanced properties: density: 97.1 to 97.9?pct relative density, Vickers hardness: 103 to 115, electrical conductivity: 65 to 69?pct IACS, volumetric shrinkage: 28.9 to 30.9?pct, and a very fine and uniform microstructure.     

机械合金化制备Fe-Co系非晶合金

在高纯氩气保护下采用高能球磨法对原子组成为Fe44Co44Zr3.5Nb3.5B4Cu1的混合粉末进行机械合金化(MA)实验,成功地制取了非晶合金粉末.利用X射线衍射(XRD)、扫描电镜(SEM)、差热分析(DTA)对其进行测试,结果表明:Fe-Co系的混合粉末在MA过程中,通过原子之间的相互固溶、扩散可形成非晶态.此非晶合金的形成是晶粒细化、球磨过程中的缺陷、应力和致密堆垛结构等多种因素综合作用的结果,这与机械合金化的合成机理之一的扩散型机制相吻合.用非晶化的热力学条件判据和动力学条件判据对此合金进行计算,其结果也表明此合金已非晶化.     

Study on Microstructure and Performance of Advanced Bush Strip

Therearemanykindsofbushmaterials ,suchasbabbitalloy ,copper leadalloy ,aluminum tinalloyandaluminum leadalloy .Therearisesabigdemandforthematerialusedinmotorastheautomotivein dustrydevelops .Inordertosatisfythedemandofhighspeedandlonglife ,anewbushmaterialAlSn8Si2 5Pb2 Cu0 8Cr0 2 (ASP ) [1] wasdevelopedinAmerica .Becausethedistributionsoftin ,silicon ,lead ,copperandchromiumareuniformanddisper sive ,thismaterialhasmanyadvantages ,suchasgoodantifriction ,highwearresistance ,goodfrictionc…