Method Of Metal Matrix Composites Research Articles

The Mechanical Properties of Aluminum Metal Matrix Composites Processed by High-Pressure Torsion and Powder Metallurgy.

Al-Al2O3 and SiC metal matrix composites (MMCs) samples with different volume fractions up to 20% were produced by high-pressure torsion (HPT) using 10 GPa for 30 revolutions of Al-Al2O3, and SiC and powder metallurgy (PM). The effect of the processing method of micro-size Al MMCs on the density, microstructure evolution, mechanical properties, and tensile fracture mode was thoroughly investigated. HPT processing produces fully dense samples relative to those produced using powder metallurgy (PM). The HPT of the Al MMCs reduces the Al matrix grain size and fragmentation of the reinforcement particles. The Al matrix average grain size decreased to 0.39, 0.23, and 0.2 µm after the HPT processing of Al, Al-20% Al2O3, and SiC samples. Moreover, Al2O3 and SiC particle sizes decreased from 31.7 and 25.5 µm to 0.15 and 0.13 µm with a 99.5% decrease. The production of ultrafine grain (UFG) composite samples effectively improves the microhardness and tensile strength of the Al and Al MMCs by 31-88% and 10-110% over those of the PM-processed samples. The good bonding between the Al matrix and reinforcement particles noted in the HPTed Al MMCs increases the strength relative to the PM samples. The tensile fracture surface morphology results confirm the tensile properties results.

Tungsten particles reinforced high-entropy alloy matrix composite prepared by in-situ reaction

In this paper, a new preparation method of metal matrix composites is presented. The W/FeNiMnAlW high-entropy alloy (HEA) matrix composite materials have been prepared by a simple and efficient technology. The HEA matrix consists of a face-centered cubic (FCC) phase, an ordered body-centered cubic (BCC) phase and W2C phase. The volume fraction and average grain size of the reinforcing phase W particles, uniformly distributed in the microstructure of HEA matrix, are 30.9% and 13.57 µm, respectively. Good metallurgical bonding between W particle and matrix is achieved, and the formation mechanism of near spherical tungsten particles is discussed, and the density of the composites is 10.55 g/cm3. The hardness of W-phase, B2 phase and FCC phase was 681.48 HV, 533.82 HV and 286.70 HV, respectively. The yield strength (σ0.2) of the W/FeNiMnAlW composites is 1241 MPa, the maximum compressive strength (σmax) and the maximum plastic strain (εp) are over 2530 MPa and 15% respectively, which showed superior mechanical properties. The effective combination of FCC phase and ordered BCC phase and the uniform distribution of W particles without edges are the main reasons for its good mechanical properties. The volume wear loss and wear rate of the W/FeNiMnAlW composites are respectively 0.42 mm3 and 4.95 × 10−3 mm3/N m, and the worn mechanism is mainly adhesive wear and abrasive wear.

Investigation into the kinetic behavior of molten aluminum pressureless infiltration into SiC preforms

Abstract Infiltration of molten metal into ceramic performs without using external force is a new fabrication method for metal-matrix composites. In this research, the kinetics of pressureless infiltration in the processing of Al/SiC composites have been investigated. In order to improve the wettability and infiltration properties, Al-6Mg (wt.%) alloy was prepared. Also, the ceramic component was coated for 15 min using electroless copper plating at a temperature of 60 – 70 °C (pH = 12.5) and a rate of 17 – 20 μm s−1. Infiltration of molten aluminum into the coated ceramic perform was successfully carried out in the temperature range of 850 to 950 °C under nitrogen atmosphere. Microstructural investigations indicated a well-bonded metal–ceramic joint. Kinetic studies showed that the melt infiltration into the ceramic foam follows an S-shaped curve. The infiltration rate was specified with respect to variables such as the experiment temperature and the size of the pores of the ceramic component. The results revealed that by increasing the temperature and the size of pores, the infiltration rate increases. For infiltrating molten metal into the 10 and 30 ppi foams, activation energies of 5.902 kJ mol−1 and 7.232 kJ mol−1 are required, respectively.

The Effect of Flake Powder Metallurgy on the Microstructure and Densification Behavior of B4C Nanoparticle-Reinforced Al–Cu–Mg Alloy Matrix Nanocomposites

When mechanical milling technique is used as a production method of metal matrix composites (MMCs), the problem of excessive work hardening adversely affecting product properties is observed, whereas the composites with homogeneous particle distribution without the use of further milling times in a ball mill can be fabricated by a new method called “flake powder metallurgy.” In this study, B4C nanoparticle-reinforced Al–Cu–Mg alloy matrix nanocomposites (MMCs) were produced by flake powder metallurgy method. The effect of flake powder metallurgy on the morphology, particle size, apparent density, nanoparticle distribution, density and hardness of B4C nanoparticle-reinforced Al–Cu–Mg alloy matrix composites was investigated. Flake powder metallurgy was assisted by using a short-term ball milling, which resulted in improved homogeneity of the B4C nanoparticle distribution. For fine Al–Cu–Mg matrix powders (FNP group) and 1 h of flake time, as the B4C nanoparticle content gets smaller from 1 to 5 wt %, density reduces from 2.7733 to 2.7350 g/cm3 and hardness increases from 117.11 to 125.21 BHN. Moreover, as the initial particle size of Al–Cu–Mg alloy matrix increases, density and hardness decrease due to agglomeration effect.

A Comparative Evaluation of the Wear Resistance of Various Tool Materials in Friction Stir Welding of Metal Matrix Composites

Friction stir welding (FSW) is the preferred joining method for metal-matrix composites (MMCs). As a solid-state process, it precludes formation of the intermetallic precipitates responsible for degradation of mechanical properties in fusion welds of MMCs. The major barrier to FSW of MMCs is the rapid and severe wear of the welding pin tool, a consequence of prolonged contact between the tool and the harder reinforcements which give the material its enhanced strength. This study evaluates the effectiveness of harder tool materials to combat wear in the FSW of MMCs. The tool materials considered are O1 steel, cemented carbide (WC-Co) of the micrograin and submicrograin varieties, and WC-Co coated with diamond. The challenges which accompany the application of harder tool materials and diamond coatings in FSW are also discussed. This study represents the first use of diamond-coated tools in FSW and the first comparative evaluation of tool materials for this application.

Fabrication of metal matrix composite by electroforming technique

An easily fabricating method of metal matrix composites was developed applying the electroforming technique. After continuous dielectric fibres are wound on a cylindrical electrode, metal matrix is electroformed. The fibres are buried in the matrix inevitably because metal matrix precipitates not on the dielectric fibres but on the electrode under the wound fibres. Winding the yam and electroforming the metal matrix are repeated until the composite has desired thickness. Al2O3—fibre/Ni and SiO2—fibre/Cu composites were fabricated by way of trial. In every combination, the matrix infiltrated into the yarn very well. This result suggests that any dielectric fibres can be dispersed in metal matrix. Tensile strength of the composites along the fibres was measured from room temperature to 600°C. Specific strength of the SiO2/Cu composite was higher than that of rolled copper. It shows the possibility of fibre reinforcement of metal by this method.

Data Acquisition and Analysis of Tensile Properties for Metal Matrix Composites

Abstract Problems arise when existing standard tension tests are used for the measurement of the properties of metal matrix composites (MMCs), largely because the elastic limits in these materials are low due to intrinsic residual stresses. A new and validated data acquisition and analysis system has been developed to provide reference data for comparison with the results of two U.K. interlaboratory exercises on the tension test method for MMCs. Particular attention is paid to assessing an automatic system for calculating Young's modulus from the input data and using plots of secant or tangent modulus against stress or strain to present information on properties in a clear and succinct manner, and to methods for validating the software. The results of both interlaboratory exercises, on different types of MMCs, showed that the analysis system produced the smallest deviation from the mean.