Fe-based Metal Matrix Composites Research Articles

Effect of mechanical milling on powder characteristics of Fe-based metal matrix composites reinforced with WC–Co and NbC particles

Effect of mechanical milling on powder characteristics of Fe-based metal matrix composites reinforced with WC–Co and NbC particles

Development of mathematical models to predict the density and hardness of Fe-ZrO2 composites

ABSTRACT Presently, Fe-based metal matrix composites are finding widespread applications in automobile, aviation and railway sectors. Powder metallurgy is one of the preferred techniques to develop these metal matrix composites. In this paper, an attempt has been made to develop the mathematical models to predict the density and hardness of Fe-ZrO2 metal matrix composites, fabricated by powder metallurgy. The experiments were performed on the plan of response surface methodology (RSM)-based Box–Behnken design. The three process parameters considered for this investigation were: sintering temperature (900–1100°C), weight percentages (10–30) of ZrO2, and sintering time (1–3 h). The responses considered for the analysis were density and hardness. Analysis of variance (ANOVA) was used to analyse the significance of the process parameters on the density and hardness. It was observed from the surface plots that sintering time and weight percentage of ZrO2 and their interaction had a significant influence on the density, whereas the weight percentage of ZrO2 individually affects the hardness. The mathematical models developed for the density and hardness were predicted at 95% confidence level. The optimum conditions for process parameters were determined and some useful conclusions were drawn.

Effects of Molybdenum and Boron Additions of Fe-Based Metal Matrix Composites by Warm Compaction Method

Effects of Molybdenum and Boron Additions of Fe-Based Metal Matrix Composites by Warm Compaction Method

Dry sliding wear investigation on tungsten carbide particles reinforced iron matrix composites

WC particles reinforced Fe-based metal matrix composites were synthesized by powder metallurgy process. The microstructure and composition of the specimens were analyzed and the wear-resistant properties against WC and alumina balls were comparatively investigated by SEM/EDS analyses. The wear rates of specimens were evaluated by optical profilometry. Microstructure exhibited austenite Fe-FCC dendrites, eutectic (iron austenite + carbides) and primary carbides. Two wear mechanisms have been identified from SEM as main mechanisms during dry sliding wear of Tungsten carbides reinforced iron matrix, namely oxidation and abrasion. The overall wear performance, which is obtained by considering the wear loss of the substrates, indicated less resistance against Alumina compared to WC ball contact.

Synergy effect of ultrafine tungsten, silicon carbides, and graphite microadditives on the Fe-based MMCs properties using the simplex lattice design

This paper is focused on the analysis of the changes in the structure and properties of metal matrix composites (MMCs) based on iron (Fe) material with tungsten carbide (WC), silicon carbide (SiC) and graphite microadditives. The synergy effect of the content of different carbides and graphite on MMCs properties was investigated using the simplex lattice design method. It was found that with the addition of carbides, namely WC and SiC, the ferrite content increases from 5 to 8% in the base material to 45% and 70% respectively. Depending on the percentage and the composition of reinforcing particulates MMCs hardness may decrease up to 25% or increase up to 30% in comparison with the base material. The residual porosity changes slightly, no more than 10%, even with an increased content of carbides and graphite, and relative volume changes of samples are between −2 to +1%.

Investigation of Mechanical Properties of Fe-Based Metal Matrix Composites by Warm Compaction for Gear Production

Investigation of Mechanical Properties of Fe-Based Metal Matrix Composites by Warm Compaction for Gear Production

Crack initiation and propagation behavior of WC particles reinforced Fe-based metal matrix composite produced by laser melting deposition

It is generally believed that cracks in metal matrix composites (MMC) parts manufacturing are crucial to the reliable material properties, especially for the reinforcement particles with high volume fraction. In this paper, WC particles (WCp) reinforced Fe-based metal matrix composites (WCp/Fe) were manufactured by laser melting deposition (LMD) technology to investigate the characteristics of cracks formation. The section morphology of composites were analyzed by optical microscope (OM), and microstructure of WCp, matrix and interface were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), in order to study the crack initiation and propagation behavior under different laser process conditions. The temperature of materials during the laser melting deposition was detected by the infrared thermometer. The results showed that the cracks often appeared after five layers laser deposition in this experiment. The cracks crossed through WC particles rather than the interface, so the strength of interface obtained by the LMD was relatively large. When the thermal stress induced by high temperature gradient during LMD and the coefficient of thermal expansion mismatch between WC and matrix was larger than yield strength of WC, the cracks would initiate inside WC particle. Cracks mostly propagated along the eutectic phases whose brittleness was very large. The obtained thin interface was beneficial to transmitting the stress from particle to matrix. The influence of volume fraction of particles, laser power and scanning speed on cracks were investigated. This paper investigated the influence of WC particles size on cracks systematically, and the smallest size of cracked WC in different laser processing parameters was also researched.

Microstructural evolution of iron based metal–matrix composites submitted to simple shear

New Fe-based metal matrix composites reinforced by around 11vol%. TiB2 ceramic particles have been characterized before and after planar simple shear tests up to 50% plastic shear strain. The morphology and the crystallographic texture of the particles have been studied by SEM-EBSD. Hardening behavior and damage development were compared for fine or coarse matrix grain size. Good ductility of the composite was observed at the macroscopic scale in both cases. Local damage by particle fracture was evidenced and quantified thanks to image processing. Effect of matrix strengthening and of particle size on damage was discussed.

Colloidal processing of Fe-based metalceramic composites with high content of ceramic reinforcement

Major difficulties of processing metal-matrix composites by means of conventional powder metallurgy techniques are the lack of dispersion of the phases within the final microstructure. In this work, processing through colloidal techniques of the Fe-based metal-matrix composites, with a high content of a ceramic reinforcement (Ti(C,N) ), is presented for the first time in the literature. The colloidal approach allows a higher control of the powders packing and a better homogenization of phases since powders are mixed in a liquid medium. The chemical stability of Fe in aqueous medium determines the dispersion conditions of the mixture. The Fe slurries were formulated by optimising their zeta potential and their rheology, in order to shape bulk pieces by slip-casting. Preliminary results demonstrate the viability of this procedure, also opening new paths to the microstructural design of fully sintered Fe-based hard metal, with 50 vol. % of Ti(C,N) in its composition.

Investigation of corrosion and wear properties of Fe based metal matrix composites consolidated by sintering and hot isostatic pressing

Many industrial applications, e.g. processing of polymers, suffer from high costs caused by corrosion and wear. Particularly the combination of both increases the requirements for the materials used. Corrosion resistant cold work steels were developed to withstand the combined attack. Resistance is achieved by a sufficient content of chromium in the metal matrix and by carbides dispersed in a martensitic matrix. A further gain in wear resistance is possible by adding hard phases to the steel to produce a particulate reinforced metal matrix composite (MMC). The common consolidation process for such MMCs is hot isostatic pressing, but they can also be processed by solid state or liquid phase sintering. This work focuses on detailed investigations of the properties in dependence on the processing route. The results show that the resulting corrosion and wear resistance depend not only on the processing method, but also on the incorporated hard phases in combination with the manufacturing method. In addition, the unreinforced metal matrices were compared to the MMC.

Improved Mechanical and Tribological Properties of Metal-Matrix Composites Dispersion-Strengthened by Nanoparticles

Co- and Fe-based alloys produced by powder technology are being widely used as a matrix for diamond-containing composites in cutting, drilling, grinding pplications, etc. The severe service conditions demand that the mechanical and tribological properties of these alloys be improved. Development of metal-matrix composites (MMCs) and alloys reinforced with nanoparticles is a promising way to resolve this problem. In this work, we have investigated the effect of nano-sized WC, ZrO2, Al2O3, and Si3N4 additives on the properties of sintered dispersion-strengthened Co- and Fe-based MMCs. The results show an increase in the hardness (up to 10 HRB), bending strength (up to 50%), wear resistance (by a factor of 2–10) and a decrease in the friction coefficient (up to 4-fold) of the dispersion-strengthened materials. The use of designed alloys as a binder of cutting diamond tools gave a 4-fold increment in the service life, without reduction in their cutting speed.

Manufacturing, microstructure and wear resistance of novel hot extruded Fe based metal matrix composites

Materials with high resistance against abrasive wear are of high interest for many tool applications, e.g. in mining industry. These materials usually contain a large amount of hard ceramic phases embedded in a metallic matrix and can only be manufactured by powder metallurgy, most often via hot isostatic pressing. Here a new manufacturing route via powder presintering and direct hot extrusion is presented, which enabled manufacturing of Fe based metal matrix composites with up to 30% of fused tungsten carbide (FTC, WC/W2C) or titanium carbide (TiC). The matrixes chosen are hot and cold work tool steels. The manufacturing process is elucidated and microstructures formed are presented. The microstructure–property relation of the new Fe based MMC is discussed.

Study for the Development of Fe-NbC Composites by Advanced PM Techniques

The development of Fe-based metal matrix composites (MMCs) with high content of hard phase has been approached by combining the use of advanced powder metallurgy techniques like high-energy milling (HEM), cold isostatic pressing (CIP) and vacuum sintering. The most innovative is the use of HEM for the obtaining of a composite powder avoiding the formation of clusters in the microstructure of the sintered material, and the study of hardenability of sintered materials. A 30 % vol. of NbC particles was mixed with Fe powder by HEM in a planetary mill under Ar atmosphere to prevent oxidation. The optimal milling time was determined by sampling every two hours until 10 hours of milling, characterising the powder by the observation of morphology and microstructure by scanning electron microscopy (SEM), and controlling the carbon content by a LECO analyser. Composite powders were compacted by CIP and then sintered in vacuum at temperatures between 1300 °C and 1375 °C, during 30 min and 60 min. The variation of density, hardness and carbon content with sintering temperature and time, besides the microstructural changes observed, permits to find the optimal conditions of processing. Afterwards, a heat treatment study was performed to study the hardenability of the cermet.

Development of Fe-based metal matrix composites

The objective of this study aims to the development of Fe-matrix composites with high carbide content to achieve properties between high-speed steels (HSS) and cemented carbides. Cemented carbides are harder and show higher wear resistance than HSS, but lower toughness. Besides, the substitution of Co or Ni for other binders is desirable due to the carcinogen character of these metals. In this work, a material constituted by an iron matrix and a 50 % wt of WC and TaC carbides is developed. High-energy milling has been used to obtain composite powders presenting a good bonding and homogeneous distribution of the carbides in the matrix. Those powders were characterised and compacted by die pressing. The green compacts were sintered at different temperatures, and properties like hardness and density were determined. Also, the wear behaviour was studied and microstructural analysis by SEM was carried out to complete the study.