如何韧化颗粒增强金属基复合材料

对颗粒增强金属基复合材料的韧性进行了综述。指出这类材料与对应基体合金相比韧性较低,其原因主要是：基体中流变应力的改变、颗粒的断裂、颗粒的不均匀分布和产伸塑性的降低。     

金属基复合材料中网络结构陶瓷增强体的制备及研究进展

介绍了网络陶瓷增强体的多种制备工艺和方法，分析了各种方法的优缺点，指出有机前驱体浸渍法是最方便、经济而有效的方法。展望了网络陶瓷增强体在金属基复合材料中的发展前景，提出了下一步需要解决的问题。     

颗粒增强金属基复合材料加工技术进展

颗粒增强金属基复合材料具有优良的物理力学性能,但材料的难加工特性限制了其应用。因此,对颗粒增强金属基复合材料加工技术的研究与发展是促进其进一步应用的关键之一。本文从加工方法、加工质量等方面综述了国内外颗粒增强金属基复合材料加工技术的进展情况,并指出了当前存在的问题及解决对策。     

网络结构增强金属基复合材料的研究进展

网络结构增强是一种全新的复合材料增强方式,其特征是增强相与基体在复合材料中形成各自连续且相互贯穿的三维网络结构,增强相因与之相互贯穿的基体所具有的韧性而得到增韧,基体则由于硬质网络结构增强相的骨架刚性承载作用而得到增强。主要评述了国内外网络结构增强金属基复合材料的制备工艺、特点及组织结构,重点介绍了复合材料的力学、热学、摩擦学性能及其今后发展趋势。     

颗粒增强金属基复合材料加工表面质量的研究

颗粒增强金属基复合材料拥有比强度高、比模量高、膨胀系数低、耐磨性良好等良好的物理性能,但是由于其特殊的组织结构,导致其加工性能较差。本文从其加工表面质量方面综述了国内外颗粒增强金属基复合材料加工技术的进展情况,从传统加工和特种加工两个方面分析了几种加工颗粒增强金属基复合材料常用的加工方法,并指出当前存在的问题和不足。     

铸造金属基颗粒复合材料

铸造金属基颗粒复合材料潘冶（东南大学邮编２１００１８）关键词颗粒复合材料，金属基，铸造自本世纪六十年代初，人们就开始对金属基复合材料（ＭｅｔａｌＭａｔｒｉｘＣｏｍｐｏｓｉｔｅ，ＭＭＣ）进行研究。长纤维金属基复合材料（ＦｉｂｅｒＲｅｉｎｆｏｒｃｅｄＭｅ...     

金属基复合材料制备技术及发展

对金属基复合材料的分类、制备技术方法进行了综述,阐述了国内外研究现状,提出目前制备技术存在问题和发展方向。     

颗粒增强金属基复合材料的特种加工研究现状

综述了颗粒增强金属基复合材料的特种加工技术的研究进展,指出了存在的问题及其解决对策。     

Grinding-aided electrochemical discharge machining of particulate reinforced metal matrix composites

A grinding-aided electrochemical discharge machining (G-ECDM) process has been developed to improve the performance of the conventional ECDM process in machining particulate reinforced metal matrix composites (MMCs). The G-ECDM process functions under a combined action of electrochemical dissolution, spark erosion, and direct mechanical grinding. The tool electrode has a coating containing a hard reinforcement phase of diamond particles. The MMC employed in this study was Al₂O₃ particulate reinforced aluminum 6061 alloy. The material removal mechanism of this hybrid process has been analyzed. The results showed that the grinding action can effectively remove re-cast material deposited on the machining surface. The surface roughness (R _a) measured for the G-ECDM specimen was ten times smaller than that of the specimen machined without grinding aid (i.e., ECDM alone). Moreover, the material removal rate (MRR) of G-ECDM was about three times higher than that of ECDM under the experimental conditions of this study. The voltage waveform and crater distribution were also analyzed, and the experimental results showed that the G-ECDM process operates in a stable condition. The relative importance of the various processing parameters on MRR was established using orthogonal analysis. The results showed that MRR is influenced by the machining parameters in the order of duty cycle?>?current?>?electrolyte concentration. This study showed that the G-ECDM process is superior to the ECDM process for machining particulate reinforced MMCs, where a higher machining efficiency and a better surface quality can be obtained.     

X-ray microtomographic studies of metal matrix composites using laboratory X-ray sources

X-ray microtomography (XMT) is a non-destructive technique that allows the internal structure of a material to be imaged by the spatial distribution of its linear X-ray absorption coefficients. This paper demonstrates the use of XMT to investigate: (1) the distribution of TiB₂ reinforcement in composites formed by powder processing; (2) the local void volume fraction as a function of position in highly deformed regions of failed tensile specimens of SiC-reinforced material allowing a valid damage parameter to be defined at high strains; (3) absorption coefficients measured at different energies simultaneously using a multichannel analyser which can sometimes be used to separate linear absorption changes due to (a) density variations and (b) compositional variations in individual voxels; and (4) the use of sequential sections to provide a three-dimensional representation of the failed specimens.     

Spray forming of Al/SiC metal matrix composites

This paper describes the as-sprayed microstructure of a model Al-4wt%Cu/SiC particulate (Al4Cu/SiC_p) metal matrix composite (MMC) manufactured by spray forming, and the relationship between microstructure and solidification conditions during manufacture. Injection of SiC_p into the melt atomization region during the spray forming of Al4Cu results in significant SiC_p incorporation into molten droplets during atomization, and relatively little incorporation during flight to the substrate and at deposition. SiC_p clustering is evident in the Al4Cu droplets and results in clustering in the as-sprayed MMC deposit. Matrix dislocation and precipitation microstructures are dependent upon local solidification conditions during spray forming. Increased dislocation density and increased quantity of fine-scale θ′-Al₂Cu precipitation is found in the α-Al(Cu) matrix where local deposit cooling rates are high, i.e. in the vicinity of the substrate/deposit interface and when increased spray distances are used in manufacture. Lower dislocation density and increased quantity of grain-boundary θ-Al₂Cu is found where deposit cooling rates are relatively low, i.e. distant from the substrate/deposit interface and at decreased spray distances. In all cases, dislocation densities are higher in α-Al(Cu)/SiC_p interfacial regions than in the α-Al(Cu) matrix. There is no evidence of α-Al(Cu)/SiC_p interfacial reaction in the as-sprayed condition indicating that cooling rates during spray forming are sufficiently rapid to prevent reaction.     

金属基复合材料及其发展现状

综述了当前国内外金属基复合材料的发展现状、性能特点、应用及制备方法。     

Transmitted light microscopy of a fibre reinforced metal

A method is presented for studying fibre damage in continuous fibre reinforced composites. It is based on contrasting the transmission of light through intact translucent fibres with the light through fractured or dead‐ended fibres. The method is applied in order to detect processing‐induced fibre fractures in aluminium reinforced with continuous alumina fibres.     

Die design optimization for axisymmetric hot extrusion of metal matrix composites

Strain rate sensitive materials such as Ti alloys, superplastic materials and metal matrix composites (MMCs) can be deformed only in very narrow range of strain rate. In this work, a new process design method for controlling strain rate in workpiece during hot extrusion process is proposed. In this approach, a coupled numerical approach of finite element analysis and optimization technique to optimal profiled die which yields more uniform strain rate distribution in the deforming region is applied to the hot extrusion process of MMCs. Extrusion die profiles are defined by Bezier curves, and FPS (flexible polyhedron search) method is used as optimization technique. The change of relative deviation of strain rate, the progressive development of die profiles with increase of iteration for optimization and the corresponding strain rate distributions are investigated. In addition, the die profiles by optimization scheme for different extrusion ratios are compared with those by analytical solution.     

PCD刀具超声振动切削金属基复合材料SiCp/Al的特性研究

试验研究了普通和超声切削新型颗粒增强金属基复合材料SiCp/Al的切削特性 ,得到超声振动切削该材料的切屑形态、切削力变化规律     

Interface considerations in high-temperature titanium metal matrix composites

Near-α titanium alloys are of interest for continuous fibre reinforced titanium-based composites owing to their better creep resistance than other titanium alloys. The main advantage of these matrices is that they can improve transverse properties of the composite at high temperature. However, cracking at the fibre/matrix interface in the as-consolidated condition has been reported with some near-α matrices. Two composites were compared in the present work: SCS-6/Ti-6-2-4-2 and SCS-6/IMI 834. Very few defects were detected in the SCS-6/Ti-6-2-4-2 composite whereas an extensive cracking of interfibre spacings was observed in the SCS-6/IMI 834 composite manufactured in the same conditions. Our investigations revealed that the fibre/matrix interaction zone is very similar in both composites, so this region cannot explain the brittle behaviour of the IMI 834 matrix. It has been established that cracking of the SCS-6/IMI 834 composite results from a combined effect of thermal residual stresses and matrix microstructure.     

Simulation and quantitative assessment of homogeneous and inhomogeneous particle distributions in particulate metal matrix composites

Reinforcement distributions play an important role in various aspects of the processing and final mechanical behaviour of particulate metal matrix composites (PMMCs). Methods for quantifying spatial distribution in such materials are, however, poorly developed, particularly in relation to the range of particle size, shape and orientation that may be present in any one system. The present work investigates via computer simulations the influences of particle morphology, homogeneity and inhomogeneity on spatial distribution measurements obtained by finite-body tessellation. Distribution inhomogeneity was simulated both by the segregation of particles away from specified regions within a microstructure and by generating point density peaks at random locations within a microstructure. Both isotropic and anisotropic inhomogeneous distributions were considered to simulate distribution patterns in PMMCs before and after mechanical working. It was found that the coefficient of variation of the mean near-neighbour distance (COV( d _mean )), derived from particle interfaces using finite-body tessellation, was essentially independent of particle shape, size distribution, orientation and area fraction in homogeneous (random) distributions, but showed great sensitivity to inhomogeneity. Increased values of COV( d _mean ) were seen for both forms of inhomogeneous distributions considered here, with little influence of particle morphology. The COV( d _mean ) was also seen to be sensitive to anisotropic clustering, the presence of which was identified via nearest-neighbour angles and cell orientations. Although generally formulated for PMMCs, the present results may be generalized to other systems containing low aspect ratio finite bodies of low to moderate area fraction.