Kind Of Metal Matrix Composites Research Articles

Processing of silicon carbide particulate reinforced aluminum alloy composites using rotary electrochemical discharge machining

ABSTRACT As a kind of metal matrix composites, silicon carbide particulate reinforced aluminum alloy composites (SiCp/Al) have been widely applied in numerous fields. However, it is still difficult to process this composite material with electrical discharge machining (EDM) at present. To address this problem, this study introduces a novel rotary electrochemical discharge – chemical composite machining (RECDM-CM) method. This method uses rotating electrodes and workpieces to improve the flushing effect of working medium and utilizes the electrolysis to reduce the recast layer thickness. The chemical reaction between sodium carbonate (Na2CO3) and aluminum oxide (Al2O3) at high temperatures is used to remove the non-conductive Al2O3 in this composite machining. Rotary electrochemical discharge – chemical composite machining is used to process silicon carbide particulate reinforced AA2009 aluminum alloy composites with the silicon carbide volume fraction of 55%. The experimental results reveal that the material removal rate (MRR) of rotary electrochemical discharge – chemical composite machining is 5.2 times that of rotary electrical discharge machining, and its relative tool wear rate (RTWR) is 37.42% of rotary electrical discharge machining. The recast layer thickness is reduced to less than 13 μm via rotary electrochemical discharge – chemical composite machining.

Investigation of solid particle erosion behavior of Al-Al2O3 and Al-ZrO2 metal matrix composites fabricated through powder metallurgy technique

The proposed research article presents an experimental investigation of solid particle erosion wear of Al2O3 and ZrO2 ceramic oxide reinforced metal matrix composite developed via powder metallurgy method. Two different kinds of metal matrix composites, Al-Al2O3 and Al-ZrO2 were developed with different proportions (0, 2.5, 5 and 10 wt%) of micro-sized ceramic oxide reinforcement powders. Vickers Hardness (HV), experimental densities of sintered samples, XRD and EDS were evaluated for mechanical characterization of fabricated metal matrix composites. Solid particle erosion wear tests were carried out at impingement angles 30–90° at varying set impact velocities of 30–90 m/s on air-jet erosion wear test rig using tiny micro-sized Al2O3 powders as an erodent. Air–jet erosion experiments were conducted as per the G76 standard for study of the steady-state erosion wear. ANOVA test revealed that wt% of reinforced contents was a significant parameter followed by impact velocity. 5 wt% of ZrO2 was observed to be the best wt% of reinforcement of all the combination of fabricated composites.

The Research of Reinforced Cu-SiCp/ZA40 and Cu-SiCp/AZ91D Metal Matrix Composites’ Mechanisms

In this paper, the strengthening mechanism of the SiCp on two different kinds of metal matrix composites was studied by adding SiCp with a diameter of 4 micron in AZ91D alloy and ZA40 alloy. The study found that the strengthening mechanism was the dispersion strengthening when 0.5-1.5%Wt SiCp was added into ZA40 zinc alloy. In order to solve the wettability of the ZA40 and the SiCp, Cu layer was coated on the surface of SiCp. When Cu-SiCp was added into the ZA40 alloy, α-Al phase blocked by Cu-SiCp at the stage of solidification and crystallization. Therefore, the α-dendrite in the crystalline tissue was decreased and the grain was refined, and the strength of the alloy was improved significantly. SiCp was added to the AZ91D composite, the strengthening mechanism was solid solution strengthening when the adding amount was less than 10%Wt. The SiCp reacted with β-Mg17Al12, generated new Al4C3 phase and strengthened phase Mg2Si, formed Mg-Al solid solution. The formation of Al4C3 played a key role in grain refined and the formation of Mg2Si replaced the harmful divorced eutectic β-Mg17Al12 phase in the material that improved the strength and hardness of the alloy. When SiCp adding amount was more than 10%Wt, in order to alleviate the agglomeration and the wettability of the SiCp and the liquid AZ91D, a Cu layer was coated on SiCp surface, the strengthening mechanisms were both solid solution strengthening and dispersion strengthening.

Preparation and property study of La(Fe, Si, Co)13/Cu composite with nearly zero thermal expansion behavior

In this work, a new kind of La(Fe, Si, Co)13/Cu composite with near zero thermal expansion property was successfully synthesized. The composite shows almost zero thermal expansion with a coefficient of thermal expansion of 0.8 × 10−6 K−1 in the temperature range of 301–325 K. In addition, the thermal conductivity and electrical resistivity were investigated. Compared with pure La(Fe, Si, Co)13 materials, the La(Fe, Si, Co)13/Cu composite shows significant improvement in both thermal and electrical conductivities. The thermal conductivity of the LaFe10.5Co1.0Si1.5/Cu composite is 25.1 W m−1 K−1, which is about five times than that of the pure LaFe10.5Co1.0Si1.5. The electrical resistivity reaches 0.16 × 10−6 Ω m. This offers a new kind of metal matrix composites with low/near zero thermal expansion, high thermal and electrical conductivity properties.

Evaluation of microstructure and mechanical properties of Al/Al2O3/SiC hybrid composite fabricated by accumulative roll bonding process

In this investigation, a new kind of metal matrix composites with a matrix of pure aluminum and hybrid reinforcement of Al2O3 and SiC particles was fabricated for the first time by anodizing followed by eight cycles accumulative roll bonding (ARB). The resulting microstructures and the corresponding mechanical properties of composites within different stages of ARB process were studied. It was found that with increasing the ARB cycles, alumina layers were fractured, resulting in homogenous distribution of Al2O3 particles in the aluminum matrix. Also, the distribution of SiC particles was improved and the porosity between particles and the matrix was decreased. It was observed that the tensile strength of composites improved by increasing the ARB passes, i.e. the tensile strength of the Al/1.6vol.% Al2O3/1vol.% SiC composite was measured to be about 3.1times higher than as-received material. In addition, tensile strength of composites decreased by increasing volume fraction of SiC particles to more than 1vol.%. Scanning electron microscopy (SEM) observation of fractured surfaces showed that the failure mechanism of broken hybrid composite was shear ductile rupture.

Modeling and optimization of cylindrical grinding of Al/SiC composites using genetic algorithms

The Al/SiC composites have received more commercial attention than other kinds of Metal Matrix Composites (MMCs) due to their high performance. However, a continuing problem with MMCs is that they are difficult to machine, due to the hardness and abrasive nature of the SiC particles. Grinding is often the method of choice for machining Al/SiC composites to acquire high dimensional accuracy and surface finish in large scale production. Based on the full factorial design (34), a total of 81 experiments, each having a combination of different levels of variables, are carried out to study the effect of grinding parameters such as wheel velocity, work piece velocity, feed and depth of cut on the responses such as tangential grinding force, roughness and grinding temperature. Modeling and optimization place a vital role in controlling any process for improved product quality, high productivity and low cost. In the present work, experimental results are used to calculate the analysis of variance (ANOVA) which explains the significance of the parameters on the responses. Based on the results of ANOVA, a mathematical model is formulated using multiple regression method. A genetic algorithm (GA) based optimization procedure has been developed to optimize the grinding parameters for maximum material removal by imposing constraints on roughness. This methodology would be useful for identifying the optimum grinding parameters in order to achieve the required material removal rate (MRR).

Characterization of Al2O3NP–Al2024 and AgCNP–Al2024 composites prepared by mechanical processing in a high energy ball mill

Mechanical alloying was used to produce two kinds of metal matrix composites based on 2024 aluminum alloy. The nanocomposites were reinforced with different percentages of Al2O3 and AgC nanoparticles. The content of nanoparticles has an important role on the mechanical properties of the nanocomposites. A milling time of 10h is enough to form the Al2024 nanocomposites. The thermograms obtained by differential scanning calorimeter show the temperatures of phase precipitation, which were identified by X-ray diffraction. The results revealed that mechanical alloying is an excellent route for the incorporation and distribution of nanoparticles into Al2024.

Internal friction in a new kind of metal matrix composites

We have developed a new kind of metal matrix composites, based on powders of Cu–Al–Ni shape memory alloys (SMAs) surrounded by an indium matrix, specifically designed to exhibit high mechanical damping. The damping properties have been characterized by mechanical spectroscopy as a function of temperature between 150 and 400 K, frequency between 3 × 10 −3 and 3 Hz, and strain amplitude between 5 × 10 −6 and 10 −4. The material exhibits, in some range of temperature, internal friction as high as 0.54. The extremely high damping is discussed in the light of the microstructure of the material, which has been characterized in parallel.

Solid Particle Erosion Behavior of Metal Matrix Composites

Phenomenological studies on the erosion of metal matrix composites (MMCs) have not been done enough. So experiments were carried out to clarify the effects of fiber volume fraction, type of reinforcement fibers and impact angle on the solid particle erosion behavior of MMCs. Three kinds of MMCs were used for the erosion experiments. They were the aluminum 6061 alloy reinforced by βSi3N4 whiskers, the aluminum 1070 alloy unidirectionally reinforced by Si-Ti-C-O fibers and the pure aluminum reinforced by SiC plain-woven cloths. In the case where the sizes of reinforcement fibers are much smaller than those of particles impacted, almost all the fibers removed from a MMC are included in a matrix material removed by the impact of particles. In this case, the difference in erosion rate is small between a MMC and the corresponding matrix material. In the case where the reinforcement fibers are included in the form of unidirectionally long fibers or cloths, a lot of fibers are removed from an eroded surface of a MMC. In this case, a MMC has much larger erosion rate than the corresponding matrix material.

Non destructive ultrasonic evaluation of fibrous metal matrix composites

An iterative numerical elastic constants optimization method associated to a classical ultrasonic immersion device is used for the entire characterization of two kinds of metal matrix composites. The usual methods of optimization are generally based on Newton's algorithm. Sometimes this algorithm converges towards relative minima that gives elastic constants which do not correspond to the physical reality of the material. As a remedy, we have developed a numerical analysis technique based on a different algorithm allowing a better convergence to the unique global solution. Using the Levenberg-Marquard algorithm, the methodology to recover the elastic constant, consists in minimizing the square deviation between calculated velocities and the experimental ones measured under variable incidence from a computer controlled ultrasonic immersion device.