Development and Characterization of Aluminium-Based Metal Matrix Composites

Aluminum based metal matrix composites were fabricated using stir casting where silicon carbide and alumina were the reinforcements. Different types of properties (physical-density, mechanical-tensile, hardness, chemical-corrosion etc.) were measured and compared with base metals/alloys. The properties were significantly varied. The highest density was obtained for pure aluminium with 5% Al2O3 whereas the lowest was obtained for AA-4032 alloy. The highest hardness was obtained for AA-4032 with 5% Al2O3 whereas the lowest was obtained for pure Al with 5% Al2O3. The highest strength was obtained for AA-6061 with 5% coarse SiC whereas the lowest was obtained for pure Al. The highest impact strength was obtained for AA-4032 with 5% Al2O3 whereas the lowest was obtained for AA-6061. The corrosion resistance of all composites was lower than that of the base materials.

Preparation of three-dimensional braided carbon fiber reinforced mullite composites from a sol with high solid content

To prepare the three-dimensional braided carbon fiber reinforced mullite （3D C/mullite） composites, an Al2O3-SiO2 solwith a solid content of 20% （mass fraction） and an Al2O3/SiO2 mass ratio of 2：1 was selected as the raw material. Characteristics andmullitization of the sol were analyzed throughly. It is found that the formation of mullite is basically completed at 1300℃ and thegel powders exhibit favorable sintering shrinkage. The 3D C/mullite composites without interfacial coating were fabricated throughthe route of vacuum impregnation-drying-heat treatment. Satisfied mechanical properties with a flexural strength of 241.2 MPa anda fracture toughness of 10.9 MPa·m1/2are obtained although the total porosity reaches 26.0%. Oxidation resistances of the compositesat 1200, 1400 and 1600 ℃ were investigated. Due to the further densification of matrix, the 3D C/mullite composites show tiny massloss and their mechanical properties are well retained after oxidation at 1600 ℃ for 30 min.

Influence of Reinforcement Type on Microstructure, Hardness, and Tensile Properties of an Aluminum Alloy Metal Matrix Composite

This paper presents the results of the comparative study of as cast microstructures and mechanical properties viz yield strength, ultimate tensile strength, elastic modulus, percentage elongation, hardness, percentage porosity and fracture characteristic of 5 wt% SiC and Al2O3 particulate reinforced Al-4% Cu-2.5% Mg matrix composites. These composite materials were prepared through stir casting process. Quantitative metallographic techniques were utilized to determine the average grain size of particles. The microstructures and tensile fracture characteristic of the representative samples of the composites were examined using optical microscope (OM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD) techniques. The experimental results demonstrate a fairly uniform distribution of 50.8 μm Al2O3 and 49.2 μm SiC spherical particles with some clustering in few areas. At the interfaces of Al2O3 and the matrix, MgO and MgAl2O4 were observed. Similarly, Al4C3 was formed at the interfaces between SiC and the matrix. The mechanical property test results revealed that, for the same weight percentage of reinforcement, Al-4% Cu-2.5% Mg/5 wt% SiC composite exhibit a 15.8%, 16.4%, 4.97% and 10.8% higher yield strength, ultimate tensile strength, elastic modulus, and hardness, respectively. On the other hand, even if some porosity was observed in the Al2O3 reinforced composite, the percentage elongation (ductility) was 31% higher than that of SiC rein-forced composite. The tensile specimen of SiC reinforced composite failed in a brittle fashion without neck formation, whereas the Al2O3 reinforced composite failed in a ductile fashion with noticeable neck formation.

Theoretical Analysis on Tensile Strength of ZA22/Al_2O_3 Short Fiber Composite Added with Ce

The tensile strength of squeeze casting ZA22/Al 2O 3 short fiber composite was measured with autograph AG 10TA universal testing machines made in Japan. The experimental results were analysed with the rule of mixture(ROM) model modified by Friend. The theoretical analysis agree well with the experimental results. Under the test condition of this study, the strengthening critical fiber volume fraction predicted is 34 5%. Because fiber volume fraction in the composite is under this value, the tensile strength of the composite is lower than that of ZA22 alloy matrix.

PEO processing of AZ91Nd/Al_(2)O_(3) MMC-the role of alumina fibers

This work reports the influence of alumina fiber reinforcement of an AZ91Nd MMC(metal matrix composite)on the PEO coating formation process in a sodium phosphate-based electrolyte.By comparison with the pure AZ91Nd,the evolution of alumina fiber during the processing and the characteristics of the resultant PEO coating were investigated.The voltage response as a function of processing time was changed.Lower voltage in the presence of alumina fiber is responsible for the lower coating thickness.The morphology and phase composition of the coatings are also influenced by the incorporation of the fiber.Firstly,the fiber is embedded in the coating and interrupts the continuity of the coating.With increasing processing time,the fiber is found to be reactively incorporated in the coating.The intention to produce a MgAl_(2)O_(4)containing coating is achieved and it is mainly accumulated near the coating surface.However,due to the low number of fibers,the Al content is overall still low and only near to the fibers the MgAl_(2)O_(4)spinel phase can form.

Taguchi approach to influence of processing parameters on erosive wear behaviour of Al7034-T6 composites

Taguchi technique was used to predict the influence of processing parameters on the erosive wear behavior Al7034-T6composite reinforced with SiC and Al2O3particles in different mass fractions.These hybrid metal matrix composites(HMMCs)werefabricated by using a simple technique called stir casting technique.Scanning electron microscope(SEM)was used to study thesurface morphology of the composite and its evolution according to processing time.The design of experiment(DOE)based onTaguchi’s L16orthogonal array was used to identify various erosion trials.The most influencing parameter affecting the wear rate wasidentified.The results indicate that erosion wear rate of this hybrid composite is greatly influenced more by filler content and impactvelocity respectively compared to other factors.This also shows the significant wear resistance with the increase in the filler contentsof SiC and Al2O3particles,respectively.

Al_2O_3SiO_2/ZL108复合材料的高温磨损性能

研究了压力铸造法研制的硅酸铝纤维增强ZL10 8复合材料的机械性能。结果表明 :复合材料在高温和室温下都具有良好的耐磨性 ,温度小于 30 0℃时 ,复合材料仍具有较好的耐磨性 ,而基体合金却严重粘着 ;而且复合材料的抗压屈服强度、抗弯强度及显微硬度比基体材料ZL10 8合金的强度高。磨损面的SEM电镜观察表明 :复合材料中纤维的存在起到抑制犁沟延伸与扩展的作用 ,从而提高了耐磨性。