俄罗斯粉末冶金高温合金

简述了俄罗斯粉末冶金高温合金的发展状况，介绍了已使用和新一代粉末冶金高温合金的成分、性能和主要用途。     

俄罗斯粉末高温合金涡轮盘的生产工艺

介绍了俄罗斯粉末高温合金涡轮盘的生工节,存在的问题和改进措施以及新合金,新工艺。目的是借鉴国外的先进技术以发展我国的粉末高温合金。     

Microstructure Evolution during Supersolvus Heat Treatment of a Powder Metallurgy Nickel-Base Superalloy

Microstructure evolution during the supersolvus heat treatment of a powder-metallurgy, low-solvus, high-refractory (LSHR) superalloy was established. For this purpose, three lots of LSHR with varying initial carbon/boron composition and thermomechanical history were subjected to a series of short-time (induction) and long-time (furnace) heat treatments followed by scanning electron microscopy/electron backscatter diffraction and quantitative metallography. The size of the (pinned) gamma grains exhibited a limited dependence on heating rate and soak time at peak temperature, and it was generally smaller than the predictions based on the classic Smith-Zener model. The differences were rationalized in terms of stereological and pinning-particle location effects. Observations of limited coarsening of the carbide/boride pinning particles were interpreted in the context of prior experimental observations and a modified Lifshitz-Slyosov-Wagner model applied previously for the coarsening of compound phases in steels.     

Deformation and Strain Storage Mechanisms during High-Temperature Compression of a Powder Metallurgy Nickel-Base Superalloy

High-temperature compression testing combined with high-resolution electron backscatter diffraction (EBSD) analysis has been used to study microstructural-scale straining processes that occur during high-temperature deformation of a powder-consolidated nickel-base superalloy, René 88DT (GE Aviation, Evendale, OH). Orientation imaging has been employed to study grain-level straining and strain storage at temperatures between 1323 K (1050 °C) and 1241 K (968 °C) for strain rates between 0.1/s and 0.00032/s at nominal strain levels between 0.1 and 0.7. Two distinct deformation mechanisms were observed. At strain rates below 0.01/s, superplastic deformation dominates, while power-law creep occurs during high rate compression. Stored strain and evolution of the grain structure during deformation are dependent on strain rate during compression. At low strain rates in the superplastic regime, low levels of stored strain and some grain growth are observed. At high strain rates, dynamic recrystallization occurs along with higher levels of stored strain within selected grains, particularly those at the high end of the grain size distribution. A constitutive model for superplastic deformation was employed to predict the temperature and strain rate dependence of the transition from superplastic to power law deformation. The transition in rate sensitivity was consistent with the transition in stored strain measured by EBSD. Superplasticity-enhanced grain growth is observed and the implications for the transition in deformation mechanisms are discussed.     

FGH95粉末高温合金蠕变裂纹扩展有限元数值模拟研究

对FGH95粉末高温合金标准CT试样在700℃下的蠕变裂纹扩展过程进行了有限元数值模拟研究.FGH95合金假设为弹性-蠕变体,蠕变变形采用Norton模型描述.蠕变裂纹扩展模拟时考虑了两种裂纹扩展速率,分别为3.25×10-2mm/h(快速裂纹扩展)和6.5×10-4mm/h(慢速裂纹扩展).数值模拟结果表明:FGH95合金在700℃下发生蠕变裂纹扩展时,弹性变形引起的标准CT试样加载线位移Vc在总位移中起主导作用,蠕变变形引起的加载线位移Vc很小,加载线位移率比值(·Vc)/(·V)远小于1,蠕变变形被限制在临近裂纹扩展路径的细长条带状区域内,裂纹尖端没有发生大范围蠕变变形.上述结果说明FGH95合金在700℃下为蠕变脆性材料,应力强度因子K可作为FGH95合金高温疲劳裂纹扩展的有效驱动力参数.     

Microstructure,Tensile Properties,and Hot-Working Characteristics of a Hot Isostatic-Pressed Powder Metallurgy Superalloy

A series of microstructure observation, tensile, and hot compression tests were conducted to investigate the variation of microstructure, tensile properties, and hot-working characteristics of a powder metallurgy (PM) superalloy with hot isostatic pressing (HIPing) temperature, to establish a basis for the parameter selection for PM superalloy preparation. The results show that the dendritic structure from the powder was not completely removed until the HIPing temperature is above the γ′ solvus; γ/γ′ eutectic formed when the powder particles were HIPed at 1533 K (1260 °C) or above. Prior particle boundaries (PPBs) were observed in alloys HIPed at 1513 K (1240 °C) and below; the PPB decoration is serious in alloys HIPed at 1483 K and 1513 K (1210 °C and 1240 °C), owing to melting and aggregation of the boride phase at the particle boundaries during HIPing; the PPBs were eliminated when the HIPing was done at 1533 K (1260 °C) or above. Tensile fracture mode of the alloy changes from inter-particle and transgranular mixed fracture to transgranular fracture with increasing HIPing temperature, which is in accordance with the change in precipitate distribution at the PPBs. The hot workability of alloy is poor for all combinations of HIPing/deformation conditions except for HIPing at sub-solvus temperature and deformation at low strain rates.

     

Microstructure, Properties and Heat Treatment Process of Powder Metallurgy Superalloy FGH95

 Microstructure and properties of nickel based powder metallurgy (PM) superalloy were presented. Effects of nonmetallic inclusions and heat treatment on microstructure and properties were discussed. Development tendency of microstructure and properties of PM superalloy was presented.     

粉末冶金用MnS粉末的制备方法

介绍了2种不同的制备MnS粉末的方法－元素化合法和反应沉淀法并作简要讨论。结果表明：元素法制备的MnS粉末氧含量较高，游离硫高，粒度较粗，但工艺简单，成本低；反应沉淀法制备的MnS粉，纯度很高，氧含量很低，无游离硫，粒度很细，平均粒度仅2μm，但工艺复杂，成本高。2种方法制备的MnS粉末的均达到粉末冶金添加剂的要求。     

Properties of a Tool Produced by Powder Metallurgy

To minimize the manufacturing costs of parts with specified operational properties, the machining processes must be optimized. Cutting accounts for at least 70% of such processes. To that end, tool materials with distinctive properties may be developed and utilized. Analysis of manufacturing components—in particular, power components in gas-turbine engines—shows the need for higher quality of the machined surfaces and more efficient use of expensive equipment with numerical and adaptive control systems, so as to ensure a wide range of cutting conditions, including high-speed cutting. To obtain products that are domestically and internationally competitive, we need to optimize cutting processes, in which the tool is the weakest link in the technological chain. Defects of the cutting tool impair the productivity and product quality. In the present work, the wear of cutting tools produced by the sintering of high-speed steel powder is studied. Tool materials based on high-speed steel with additional alloying by titanium carbide (carbide steel) are shown to be highly wear-resistant. They may be classified as a new category of self-organizing tool materials. The results indicate the expediency of additional alloying by two methods to modify the tool friction and wear: (1) alloying with compounds that considerably reduce the self-organization by decreasing the frictional coefficient at working temperatures; (2) alloying to expand the range of self-organization. Both methods result in lower frictional forces and temperatures, as confirmed by the change in wear resistance and frictional characteristics. The wear resistance of such tools is found to be 2–3.5 times that of regular high-speed steel tools.     

高温合金粉末内部孔洞的研究概况

阐述了等离子旋转电极工艺（PREP）制取的镍基高温合金粉末内部孔洞的形成机理，分析了导致孔洞形成的因素，提出了降低粉末内部孔洞应采取的措施，研究结果表明：孔洞的尺寸随着粉末粒度的下降而减小，在相同雾化制粉工艺参数条件下，粗粉中孔洞的数量多于细粉。随着棒料转速的提高，空心粉数量增加，此外，雾化室内混合惰性气体压力降低或混合惰性气体中氩气含量提高，均能使空心粉数量降低。     

Developmental trends in European Powder Metallurgy

The state of the art and development trends in European powder metallurgy are analyzed. The main ways to improve the production technology and quality of parts are discussed. It is pointed out that the injection-molding production of powder-metallurgy parts is rising. The areas of their application are analyzed. It is informed that European research centers and development programs on powder metallurgy grow in number. The role of the European Powder Metallurgy Association is indicated.     

钢结硬质合金预合金粉的研究

分析了钢结硬质合金预合金粉组织的特征，研究了不同含碳量对预合金粉组织的影响，制定出针对钢结硬质合金预合金粉特点的制粉工艺，通过还原退火处理降低了预合金粉的氧含量，并使合金粉组织得到了改善。     

粉末冶金发泡法制备泡沫铝工艺研究

泡沫金属是近年来发展起来的一种新型结构功能材料.采用粉末冶金发泡法制备出孔隙率为45%-85%、平均孔径＜5mm的多孔泡沫铝合金试样,并用极差分析法讨论了发泡温度、保温时间和发泡剂的状态对泡沫铝合金的孔隙率的影响,得到了最佳制备工艺条件.     

硬质合金用超细碳化铌(钽)粉生产工艺条件及质量控制的探讨

在碳化法生产铌(钽)碳化物的基础上,针对硬质合金用超细碳化铌(钽)粉的生产过程进行了因素分析,并总结概括了其质量控制要素,提出了具体的改进措施。     

FeNiCrWRE粉末冶金材料的研究

研究了含稀土元素的FeNiCrWRE粉末的研制工艺及其在粉末冶金制品和热喷涂方面的应用。探讨了稀土元素对FeNiCrWRE粉末性能的影响。结果表明,加入稀土元素可以获得致密化程度较高、分布均匀的组织,明显增加了合金碳化物中铬的含量,使碳化物的显微硬度提高,从而提高了材料的耐磨能力。