Experimental Phase Diagram Investigations in the Ni-Rich Part of Al-Fe-Ni and Comparison with Calculated Phase Equilibria

The phase equilibria in the section Ni₃Fe-Ni₃Al and phase boundaries of γ′(Ni₃Al) at 1000 °C were studied by a combination of powder X-ray diffraction (XRD), differential thermal analysis (DTA), and electron probe microanalysis (EPMA). The existence of a continuous solid solution at 450 °C was confirmed by a linear decrease of the lattice parameter from Ni₃Al to Ni₃Fe. The phase boundaries of γ′ with γ and the B2-type phase were determined at 1000°C by EPMA. A vertical section of the phase diagram from Ni₃Al to Ni₃Fe above 450 °C, including the liquidus temperatures, is proposed based on the DTA investigations. The invariant four-phase equilibrium U: L + γ′ = γ + B2 is found to occur at 1366 ± 1 °C. The experimental data are compared with a calculated phase diagram obtained by extrapolation from the corresponding binary data sets.     

Plasma Electrolytic Oxidation of Arc-Sprayed Aluminum Coatings

Different posttreatment methods, such as heat treatment, mechanical processing, sealing, etc., are known to be capable to improve microstructure and exploitation properties of thermal spray coatings. In this work, a plasma electrolytic oxidation of aluminum coatings obtained by arc spraying on aluminum and carbon steel substrates is carried out. Microstructure and properties of oxidized layers formed on sprayed coating as well as on bulk material are investigated. Oxidation is performed in electrolyte containing KOH and liquid glass under different process parameters. It is shown that thick uniform oxidized layers can be formed on arc-sprayed aluminum coatings as well as on solid material. Distribution of alloying elements and phase composition of obtained layers are investigated. A significant improvement of wear resistance of treated layers in two types of abrasive wear conditions is observed. This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain Montavon, Ed., ASM International, Materials Park, OH, 2007.     

高压水射流在铝板带清洗设备上的应用

介绍了铝板带清洗原理及高压水射流喷射距离的选择,通过对打击力进行理论分析,建立了打击力的计算公式,从而找到提高清洗效果的途径;对清洗机组设备结构与工艺过程进行了介绍,总结了铝板带的高压清洗系统节水、节能、提高洗净率的方法;文中给出了入射角、压力、喷嘴结构、喷射距离、喷流角度等实用参数选择的原则和方法,具有实用价值。     

冒口对A201(0.75%Ag)铝合金平板铸件力学性能影响的研究

系统地改变A201(0.75%Ag)铝合金平板铸件的长度、厚度及冒口大小,以探讨这些冒口对不同尺寸A201平板铸件抗拉强度及微孔隙的影响程度,进而在铸造生产中,可为冒口设计及金属凝固控制提供参考。型砂为100%硅砂。试验结果表明,A201铝合金平板铸件的力学性能及微孔隙受冒口补充的影响,当微孔隙增加时,会降低铸件的抗拉强度及伸长率。     

SiCp/AlCuMgAgCe复合材料的显微组织与力学性能

采用压铸浸渗法制备了53%SiCp增强的AlCuMgAgCe基复合材料。通过X射线衍射、金相观察、扫描电镜与透射电镜分析以及力学性能测试,研究了SiCp/AlCuMgAgCe复合材料的显微组织与力学性能。结果显示,在AlCuMgAgCe合金中加入53%体积分数的SiC颗粒后,复合材料的组织致密,分布均匀,其断裂方式包括界面脱开、基体韧断和增强体开裂,SiC颗粒与基体之间并没有发生明显的界面反应。在185℃的等温时效析出过程中,复合材料的析出相主要由Ω相和少量θ′相组成。     

200kA预焙槽强化电流过程中发生电解质粘度增加的实践探讨

通过分析200kA预焙槽在强化电流条件下电解质粘度增大的原因及对电解生产的影响,提出了规范电解生产作业制度及处理电解质粘度过大的建议,以实现降低工人劳动强度,达到工艺参数优化和提高电流效率的目的。     

7050铝合金低频电磁铸锭挤压板的微观组织及时效特性

研究了低频电磁铸造和普通DC铸造7050铝合金铸锭经挤压变形后所得板材制品的微观组织及时效特性.结果表明,低频电磁铸锭挤压板材的微观组织保持了其原始铸态组织晶粒细小的特点.在相同挤压比条件下,低频电磁铸锭挤压板的平均晶粒直径约为10 μm,而普通DC铸锭挤压板的平均晶粒直径约为20 μm.低频电磁铸锭挤压板具有更快的时效强化速率和更好的时效强化效果.两种挤压板在120℃进行单级时效时,低频电磁铸锭挤压板经8 h达到强度峰值,其纵向和横向的拉伸强度分别为656和596 MPa;而普通DC铸锭挤压板经12 h才达到强度峰值,其纵向和横向的拉伸强度分别为647和590 MPa.     

热处理对铝板基PS版电解腐蚀性能的影响

采用极化曲线测定、扫描电镜和金相显微镜技术,对比国外优质1050 PS版板基,研究了热处理工艺对板基电蚀性能的影响.结果表明,具有大量细及均匀分布的第二相颗粒和均匀晶粒组织的板基电解腐蚀性能好.经过600 ℃×3 min的高温快速退火处理后的板基微观组织得到细化,均匀性提高,细小弥散的第二相颗粒大量析出,板基电解活化性能增强,腐蚀均匀、稳定,电解腐蚀性能显著提高.     

添加造孔剂法制备开孔泡沫铝及其性能研究

以球形尿素颗粒为造孔剂,采用传统的粉末冶金工艺制备开孔泡沫铝并研究了其性能.结果表明,添加造孔剂法制备的泡沫铝可以任意控制孔隙率及孔径的大小,且孔结构良好,保持了造孔剂的形状;高的烧结温度使泡沫铝的压缩强度提高,但过高的温度将导致孔壁熔化.本试验制成的泡沫铝其压缩曲线和泡沫金属典型压缩曲线相似,且抗压强度和经典理论计算结果一致.     

PTC热敏电阻铝电极玻璃成分与电性能的关系

作者通过实验证明PTC热敏电阻器欧姆接触、通电老化、高温老化及潮热老化与铝导电浆料中玻璃组分的关系.在B、Si、Pb玻璃中添加Zr、Al、V和Na的氧化物,PTC热敏电阻器的电性能可以满足使用要求.