Al、Cu二元合金系烧结过程的原位观察

利用高温光学显微镜（HTOM）对由纯铝粉和纯铜粉制得的二元粉末体系进行了原位烧结试验,原位观察结果表明：经典烧结理论对塑性粉末体系不再适用;该体系烧结的典型物理过程可概括为颗粒边界熔化、晶界熔化、颗粒熔化,最后为合金元素铜的扩散均匀化,而这四个阶段在时间上并不能严格分开,而是交叠进行的;边界熔化受颗粒表面氧化膜破碎、表面曲率和颗粒变形等因素影响;晶界扩散在烧结过程中始终起着非常重要的作用.这些结果为进一步合理制定和优化烧结工艺提供了直接的参照依据.     

装配模型在粉末冶金模具CAD系统开发中的应用

针对粉末冶金模具CAD系统的开发,研究了在Unigraphics NX3.0平台上基于装配模型的CAD系统二次开发方法.详细介绍了装配模型在粉末冶金模具CAD系统中的应用、装配建模的方法,以及系统开发中运用到的关键技术.系统开发实践表明:基于装配模型的开发方法有效地保证了零件设计的可装配性,提高了设计自动化程度.同时,最大限度地保证了零件与装配体修改的同步更新.     

INVESTIGATION ON THE DENSITY UNIFORMITY OF PRESSED PARTS BY LOW-VOLTAGE EI,RCTROMAGNETIC COMPACTION

Powder metallurgy is an efficient approach to fabricate varieties of high performance structure materials, function materials and special materials working under limited conditions. Research and development of new efficient technology to form high-density,high-performance and net shape parts is a key to widen application and development of powder materials. Recently, the low-voltage electromagnetic compaction (EMC) has been used by present authors to compacted copper, tin, aluminum powders and the products with 99% relative density have been acquired. In this work, the research has been extended to investigation on the density uniformity of pressed parts. The analysis results show that the density of the part compacted by low-voltage EMC decreases gradually in press direction as static compaction. But it is higher and more homogeneous. The densit3““ of the top part increases gradually from the center to the outer, which is just reversal of the bottom part. In some extent, the higher the discharging voltage is, the higher the densiO‘ is and the more homogeneous the distribution is. In addition, repetitive compaction can improve the density of powder parts and the distribution uniformity.     

Mechanical alloying of Mo—Si—Fe powders

Mechanical milling behavior of Mo-Si-Fe powders was investigated u sing XRD, SEM and TEM techniques. The mixtures of elemental molybdenum (>99%), s ilicon (>99%) and iron (>98%) powders with a stoichiometry of Mo5-xFe xSi3 (x=0.5, 1, 2) were milled in a planetary mill for up to 195 h. For all three powder mixt ures, high-energy milling of 60h led to formation of the Mo(Fe, Si) supers aturated solid solution (Moss); and to a remarkable expansion of the solub ility of Fe, Si in molybdenum. The transformation of Moss to an amorphous phase was identified after longer time milling. In the milling process, the grain size of Mo (Fe, Si) decreased gradually and the internal stress increased linearly. After 40 h milling, the grain size was reduced to about 11 nm. SEM analysis of milled powders showed that the particle size increased initially with milling time. After 195 h milling, particles exhibited a spherical morphology and the particle size were reduced to about 100 nm.     

粉末压制技术的研究与开发

粉末压制成形是生产低成本高附加值烧结产品的关键技术之一。烧结技术有许多应用，不仅仅用于制造机械零件还可以用来制造模具、磨石等。本文回顾了作者在东京大学工业技术研究所30年来所主持的压制技术的研究与开发。作者取得的主要成就如下：普通粉末成形(粉末锻造、流铸法、法算机数字控制压制)，表面精致的烧结模(多孔模、喷粉模、快速制造)，铸铁粉末烧结(脱碳铸铁粉末烧结、金刚石砂轮与铸铁的烧结)，纤维冶金，高导电性金属／聚合复合材料以及磁粉精制。这些新工艺中许多一部分已经用于实际生产中。     

2A12/SiCp陶瓷基复合材料伪半固态触变成形研究

在粉末冶金的基础上，结合半固态金属加工技术和21世纪陶瓷基复合材料成形的发展趋势，从而提出了陶瓷基复合材料伪半固态触变成形工艺，并且应用该工艺将2A12铝合金粉末和基体SiC颗粒按不同比例混合而得到的复合材料制备出卫星角框架制件。通过金相分析、拉伸等试验，证明了用该工艺成形陶瓷基复合材料是可行的。结果表明，该工艺成形的零件微观组织比较均匀，硬度比较高并且具有一定的塑性，为陶瓷复合材料以及高熔点材料在更多领域中的应用起到推进作用，同时为该工艺的进一步研究奠定了基础。     

提高身管寿命的粉末冶金内衬和衬管

本文介绍了国外用粉末冶金制合金内衬方法的特点,工艺过程和应用实例,阐述了钼合金衬管制造方法的研究和进展。     

粉末冶金法制备SiC颗粒增强AZ81镁基复合材料性能研究

研究了粉末冶金法制备SiC颗粒增强AZ81镁基复合材料的力学性能及力学性能变化的机理。实验结果表明，与AZ81基体相比，通过加入一定合适体积的SiC颗粒，SiCp／AZ81复合材料的拉伸强度、断裂韧性、硬度均有了较大提高，其最大值分别达到271．61MPa，5．96MPa·m^1/2，2．52GPa。