New technologies in powder metallurgy and ceramics developed in Belarus. A survey

Basic trends in scientific and technical activity, new technologies in powder metallurgy, and new materials created at the Institute of Powder Metallurgy of the National Academy of Sciences of Belarus since the early 1990s through the present day are considered. The article reviews the contribution of Belarus scientists to the development of sintered functional materials and anti-friction composite materials, the development of technologies of drop forging of sintered billets, infiltration of powder compacts, warm pressing of powders and additional pressing of compacts, in the creation of porous powdered materials with anisotropic structure, porous-capillary materials, and industrial ceramic, in the use of technologies of powder metallurgy to fabricate diamond tools, and create materials and technologies of thermal deposition of coatings from powders. __________ Translated from Poroshkovaya Metallurgiya, Nos. 1–2(447), 118–128, January–February, 2006.     

Structure and properties of powder metallurgy phosphorous steels

The effect of structure on the properties of powder metallurgy steels alloyed with phosphorus was investigated. Initial mixtures were prepared by the traditional method and by mechanical alloying. Mechanical alloying decreased the sintering temperature, increased the density, and improved the properties thanks to the formation of dispersed phases, a high-density cellular dislocation distribution, and the trapping of phosphorus atoms by the dislocation atmosphere, which prevented coagulation of the phosphides. It was established that when closed porosity is formed, the changes in mechanical properties and fracture resistance do not agree. National Research Institute for Powder Metallurgy and Coatings Technology, Perm'. Translated from Poroshkovaya Metallurgiya, Nos. 3–4(406), pp. 59–64, March–April, 1999.     

粉末冶金发展状况

随着全球工业化的快速发展,粉末冶金技术已广泛应用到各个领域。粉末冶金具有原材料利用率高,制造成本低,废料损耗少,材料综合性能好,产品尺寸精度高且稳定等优点。此外,粉末冶金可用于制备传统方法无法制备的材料和难以加工的零件,因此,研究粉末冶金的发展越来越具有重要的意义。粉末冶金产品已能满足现中国国民经济建设的基本需求,更重要的是粉末冶金科学为中国的国防建设提供了新材料,为重点军事工程建设做出了重要贡献。主要论述了粉末冶金演变历史,北美、欧洲、日本、中国及其他国家粉末冶金产业的发展状况,粉末冶金新技术和新材料的发展及应用;并分析了中国在此行业中存在的不足;针对中国粉末冶金产业和技术发展,提出几点建议。     

News from the European powder metallurgy association: Epma marks its tenth anniversary under conditions of increasing globalization of powder metallurgy

EPMA notes increasing shipments of West European powder metallurgy products in 1998 compared with 1988. Growth has been particularly strong in Germany, Switzerland, Austria, and Spain. This is closely connected with the growth of automobile production. Problems of automobile construction, including powder metallurgy, were considered at a special EPMA seminar on 29 May 1999. The powder metallurgy specialists noted that there is a clear tendency towards globalization of automobile producing companies and their suppliers, including powder metallurgy manufacturers. For further development of European powder metallurgy the following are necessary: to be in closer touch with customers; to have a critical mass for research and development in order to promote cutting edge technology, design, and engineering; a global presence and a leading market share, giving financial strength; the capability to design and supply systems; coordination of European demands for automobile parts with those in America; a decrease in the prices of high-quality powders for producing high-strength and dense parts; attainment of more competitiveness of powder metallurgy production technology as in joining and processing technologies. Translated from Poroshkovaya Metallurgiya, Nos. 5–6(413), pp. 123–126, May–June, 2000.     

Electroerosion resistance and structural phase transformations in electrospark and laser deposition of titanium alloys using composite ceramics based on ZrB2-ZrSi2 and TiN-Cr3C2 systems

The paper examines the mass transfer kinetics, structure, phase and chemical compositions, and micromechanical properties of electrospark and laser coatings on titanium alloys (including their combination) deposited using composite materials based on the ZrB₂-ZrSi₂ and TiN-Cr₃C₂ systems. The electrospark deposition of both materials is characterized by a relatively high mass-transfer coefficient (∼40–60%) over a wide range of treatment time t ≥ 1 min/cm². It is determined that after prolonged electrospark deposition (t = 7 min/cm²), ZrB₂-ZrSi₂ coatings have structurally heterogeneous surface with smoothed Ti-alloy localities caused by the melt crystallization and modified with alloying components. It is shown that ZrB₂-based coatings are promising along with conventional wear-resistant coatings based on refractory titanium compounds. __________ Translated from Poroshkovaya Metallurgiya, Vol. 47, No. 1–2 (459), pp. 151–161, 2008.     

机械合金化在Fe-Si合金制备中的应用

机械合金化是一种新的材料制备方法, 近年来在功能材料的制备中得到了广泛的应用. 该文简要回顾了机械合金化的发展历史, 阐述了机械合金化的原理及反应机制, 介绍了机械合金化技术在过饱和固溶体、非晶、纳米晶及金属间化合物等领域的应用状况. 指出机械合金化过程的热力学和动力学研究及合金相结构、性能与球磨工艺条件之间的规律是今后研究的重点, 后续处理工艺的改进是产品实现从实验室向工业应用转变的重要保证.     

Selection of Alloying Method to Produce Iron-Based Powder

There are different methods to produce low-alloyed iron-based powders. The properties of such powders depend on the method of alloying as well as on the characteristics of the basic grade of iron powder. A comparative experimental study to estimate the influence of the basic iron powders on low alloyed powder properties has been conducted. The method of co-reduction of powdered oxides that contain alloying elements and selected iron powder grades has been selected. Chemical and mass spectrometer analysis has shown satisfactory alloying element distribution. Tensile strength test of the sintered parts has shown that the best results are obtained for specimens produced from low alloyed powder of Indian “Blue Dus” concentrate as the basic iron powder grade. __________ Translated from Poroshkovaya Metallurgiya, Nos. 5–6(443), pp. 8–3, May–June, 2005.     

Preparation of TiAl15Si15 intermetallic alloy by mechanical alloying and the spark plasma sintering method

This work is devoted to the preparation of alloys based on intermetallic compounds in the Ti–Al–Si system by powder metallurgy using mechanical alloying and the spark plasma sintering (SPS) method. The aim was to describe the formation of intermetallic phases during mechanical alloying of TiAl15Si15 (wt-%) alloy and to consolidate the powder prepared by optimised conditions. Phase composition, microstructure and hardness of compacted alloy were determined. Four hours of mechanical alloying is sufficient time for preparation of pure elements free material composed only of intermetallic phases. After consolidation, the TiAl15Si15 alloy has a homogeneous structure composed of silicide (Ti₅Si₃) in aluminide (TiAl) matrix. The hardness of the material reaches 865?±?42 HV 5.     

粉末冶金法制备TiAl基合金

综述了粉末冶金制备TiAl基合金的几种方法，其中包括机械合金化，自蔓延高温合成、反应烧结及预合金粉末法等，同时论述了上述方法的局限性和发展趋势。     

Strength and Heat Resistance of New Antifrictional Powder Metallurgy Materials Based on Nickel

The hightemperature strength and heat resistance of new powder metallurgy antifrictional materials based on the powder metallurgy nickel alloy É:P975 were investigated. The effect of alloying elements on the structure and properties of the new materials at high temperatures was studied. It is shown that the developed materials can be successfully used in friction units operating at temperatures up to 900°C in air.     

Structure and mechanical properties of sintered Ni free structural parts

Abstract

Ni, Cu and in some cases Mo are the alloying elements which have traditionally been used in sintered steels. High performance of powder metallurgy (PM) structural parts from Fe powders is reached mainly by alloying of Ni. The use of Mn in Fe base PM structural parts has been avoided because of its high affinity to oxygen. It is difficult to sinter Mn steel, without oxidation, in industrial atmospheres. However, the PM industry follows also possibilities in order to develop Ni free sintered steels which render as high mechanical properties as diffusion alloyed Ni containing sintered steels and further fulfil the requirements of health protection. In recent years Mn have been introduced as alloying element in Fe based structural parts, on laboratory scale and also for pilot scale production. In this paper the factors that contribute to the structure and mechanical properties of sintered Mn steels are summarised.     

粉末冶金摩擦材料的应用现状及对原材料的要求

粉末冶金技术在中国的应用获得快速发展。系统介绍了粉末冶金摩擦材料在飞机刹车、坦克制动、离合器片、风电制动器主轴、高速列车制动闸片等领域的国内外应用现状,并对粉末冶金摩擦材料的原材料提出了具体要求,以期对粉末冶金技术的进一步发展提供参考。     

Contemporary powder metallurgy: Achievements and problems

The world’s production and use of powders is discussed. Factors that influence the development of powder metallurgy and measures that will promote wider application of powder products are considered. Estimates for the development of powder metallurgy up to 2011 and some developments that won awards of the Metal Powder International Federation (MPIF) in 2005 are presented. __________ Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 3–4 (454), pp. 122–126, 2007.     

机械合金化制备铜碳合金增强铜-石墨复合材料

通过机械合金化制备Cu-5 ％C合金粉,并采用粉末冶金工艺制备铜碳合金增强铜-石墨复合材料即Cu-(Cu-5％C)-C,研究了制粉工艺和Cu-5％C合金粉对该复合材料显微组织及物理性能的影响.结果表明:随着球磨时间的增加,合金粉中铜的晶格常数先增大后减小,衍射峰强度不断降低,半高宽逐渐增大;球磨40 h后合金粉中的石墨衍射峰消失,再经400℃退火3h则球磨产生的次生相Cu2O衍射峰消失,且石墨峰未复现.当石墨含量为4％,合金碳含量不超过1.5％时,Cu-(Cu-5 ％C)-C复合材料试样的电导率均达61％ IACS以上;当合金碳含量为1.0％时,复合材料的屈服强度显著提高;当合金碳含量达到1.5％时,复合材料中的合金相严重分解,其增强效果大为减弱.     

铁基烧结零件所需原辅材料性能探讨

烧结零件的力学性能,主要由零件密度、材料组成、材料特性、材料制备工艺等所决定。通过优化材料组成和制备工艺,可以降低零件的综合成本。所谓的新材料新工艺新技术,在零件制造的第一步——原材料,就已经展露出其特有的优势。着重综述了铁基粉末冶金零部件采用的各类原材料,对其力学性能、加工性能、使用性能的应用现状以及发展前景进行分析和探讨,力求探索优化烧结零件性能的有效途径。     

Interconnection between short-term strength, static stress-rupture strength, and creep resistance of tungsten, molybdenum, and alloys based on them

Comprehensive analysis of experimental data for the high-temperature mechanical properties of commercial purity tungsten, molybdenum, and their alloys with solid solution, dispersion, and mixed hardening prepared by powder metallurgy with different forms of uniaxial tension is provided. It was established that for materials of this class at high temperature (0.5–0.8 T_m) there is a close correlation between short-term and static stress-rupture strength, and creep resistance, which is described by unified functional dependences that are common for all of the metals and alloys studied. Institute of Strength Problems, Ukraine National Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 7–8(408), pp. 93–99, July–August, 1999.     

Effect of Iron Content on Sintering Behavior of Ti-V-Fe-Al Near-β Titanium Alloy

Two near-β Ti-10V-3Fe-3Al and Ti-10V-2Fe-3Al alloys were produced by blended elemental powder metallurgy using hydrogenated titanium and V-Fe-Al master alloy powders. The distributions of the alloying elements were investigated at different stages of transformation of the heterogeneous powder compacts into the final homogeneous alloy product. The influence of iron content on chemical homogenization, densification, microstructure, and mechanical properties of as-sintered alloys was discussed with respect to the fast diffusion mobility of iron in titanium. It was concluded that a 1 pct increase in Fe content, as the alloying element with the fastest diffusivity in titanium, has a positive effect on densification. However, this also results in some grain coarsening of the final material. The attained mechanical properties were comparable with those of cast/wrought near-beta titanium alloys.     

Supertransus processing of TiAl-Based alloys

Fine-grained lamellar microstructures would be expected to exhibit high strength, creep resistance, fracture toughness, and moderate ductility. High-temperature extrusion was used to produce fine-grained lamellar microstructures in both ingot metallurgy (I/M) and powder metallurgy (P/M) Ti-48Al-2Nb-2Cr alloys. The effect of processing parameters, such as extrusion temperature and cooling rate, on the microstructure and properties was determined. In addition, the thermal stability of the microstructure was evaluated by subsequent heat treatments. Although fine-grained lamellar microstructures were generated in both ingot and powder metallurgy materials, processing had a significant effect on the microstructure and properties of the resultant materials. This article is based on a presentation made in the symposium “Fundamentals of Gamma Titanium Aluminides,” presented at the TMS Annual Meeting, February 10–12, 1997, Orlando, Florida, under the auspices of the ASM/MSD Flow & Fracture and Phase Transformations Committees.     

Powder metallurgy in North America continues to grow

The current state of the production of metal powders and articles made from metal powders in North America is considered. New technologies that yield an increase in the density and an improvements in the mechanical properties of powder materials are considered. Technological developments and products that were awarded prizes by the North American Federation of Powder Metallurgical Enterprises in 2005 are presented. __________ Translated from Poroshkovaya Metallurgiya, Nos. 7–8(450), 122–128, July–August, 2006.     

Fatigue and Compression Characteristics of Al 6061–B 4 c Composite Materials

Aluminum matrix composites reinforced with boron carbide are a kind of materials that are widely used because of high strength, low density, and improved tribological properties. In this study, mechanical properties of Al 6061–B4C composites reinforced with B4C of three different particle sizes were investigated. In the Al 6061–B4C composite materials, produced by the powder metallurgy methods (extrusion of billets obtained by sintering at temperature of 550°C under pressure of 450 MPa), the change of mechanical properties such as hardness, compressive strength, and fatigue life, related to B4C particle size and the applied heat treatment mode (aging at 180°C for 5 h), were investigated. The hardness of the materials is increased with B4C grain size and the heat treatment. After the heat treatment, the fatigue life of Al 6061–B4C (3 μm) material increases slightly, while that of the composite materials decreases with larger size of B4C reinforcement. The fatigue life of the composite materials reinforced with a larger grain size B4C is reduced by heat treatment. While the compression test data of untreated composite materials were similar to each other, the heat treatment increased these values in all samples. The highest increase in the compression strength was observed in the composite reinforced with 17 μm sized B4C. The addition of graphite reduces the deformation ability of the composites.