Papers by Keyword: Metal Matrix Composite (MMC)

Abstract: Ceramic particle reinforced metal matrix composites (PRMMCs) combine the strength and brittleness of ceramics with the toughness of a metallic matrix. In order to use these materials in construction and operational design their fracture mechanical behavior must be evaluated. In this study, a 30 vol.-% Al₂O₃ reinforced austenitic TRIP steel processed by powder metallurgical technique was investigated using precracked miniature SENB-specimens in 3-point-bending. An elastic-plastic analysis by means of the J-integral method in combination with optical crack observation showed the materials ability of stable crack growth, i. e. R-curve behavior. In addition to the mechanical tests microstructural studies were performed, whereby particle debonding and fracture as well as martensitic phase transformation and crack bridging within the matrix were identified as fracture energy dissipating mechanisms.

Abstract: This paper focused on fabrication of Al-6vol%SnPb from recycled Aluminium and recycled solder and its characterization in different sintering temperature. Al-20SnPb was fabricated by using cold forging process of flakes chip raw materials. Constant pressure (56.4 MPa) was used to implement cold forging process. Various sintering temperature (200 0C, 250 0C, 300 0C and 3500C) was studied to obtain the optimum hardness properties. The diffraction pattern of X-Ray diffraction (XRD) reveals the influence of varying sintering temperature of Al-6vol%SnPb. Vickers hardness result also support that, optimum result obtained is at sintering temperature 300 °C.

Abstract: Friction stir processing is a novel process evolved to fabricate surface metal matrix composites. Rice husk ash (RHA) is an agro-industrial waste and by product of rice husk. The feasibility of incorporating RHA powder into aluminium alloy AA6061-0 as reinforcement particles to make surface matrix composite via FSP is reported in this paper. The optical micrographs revealed a homogeneous distribution of RHA particles which were well bonded with the matrix in both first and fourth-passes of the FSP due to mechanical stirring. Microhardness of the stir zone SZ with the RHA particles of I-pass increased to about 106 HV, 40% higher than that of the base material 66 HV by dispersed RHA particles.

Abstract: There are relevant reports on preparing TiB₂ particle reinforced metal matrix composite (MMC) anti-wearing coating by plasma spraying and HVOF spraying methods successfully. The research uses electric arc spraying with low cost and convenient operation to prepare four TiB₂ particle reinforced composite coatings with high bonding strength and uniform microstructure. It makes comparative study on elevated temperature erosion actions of coating and 45CT of electric arc spraying. The results indicate the coating has excellent erosion wearing resistance. TiB₂ particles in M-TiB₂ coating have small size, have good unity with metallic matrix, and are distributed on metallic matrix with high hardness relatively uniformly, and porosity of coating is low. Such MMC coating microstructure feature avoids micro-cutting of coating effectively, and reduces plastic deformation and material transfer of wearing surface. The coating has excellent erosion resistance.

Abstract: In the present study, a high power direct diode laser (HPDDL) was used to deposit composite coatings consisted of Ni-based superalloy Inconel 625 matrix and of WC reinforcement particles with a volume fraction of 60%. The influence of parameters, such as laser power beam (heat input) and WC particles size in the cladding powder on the coatings microstructure and erosion wear properties was investigated. The coatings were examined by optical metallography and scanning electron microscopy. The results showed that direct diode laser cladding provides non-porous coatings with homogeneous distribution of WC particles and very low degree of WC dissolution during cladding process. Erosion resistance of the composite coatings decreases with the size of WC particles decreasing.

Abstract: The heat conditions of laser gas nitriding (LGN) of titanium alloy Ti6Al4V by high power diode laser (HPDL) were investigated experimentally by non-contact pyrometric measurements and infrared camera analysis. Additionally direct observations of the weld pool shape were conducted by means of high speed digital camera. In the numerical study of the laser surface processing of titanium plate 3D model of heat flow was examined. Results of temperature values, distribution and temperature isotherms obtained from the 3D model were next applied in the two-dimensional stationary model of liquid metal flow in the weld pool. Experimental and numerical study showed that the temperatures of the weld pool during laser gas nitriding of the titanium alloy are significantly higher compared to these determined during laser melting in argon atmosphere at the same heat input. Additionally severe turbulences of liquid metal in the weld poll (Marangoni convection) were found during both experimental and numerical analysis.

Abstract: The work explores the production of Al/SiC and Al/SiC/NiAl₂O₄ composites by thixoforming compacted mixtures of AA7075 machining chips and reinforcing particles. It is analyzed the influence of processing parameters in the various processing steps, such as mixing, compacting, heating and thixoforming, in the final quality of products. Results showed the general viability of producing composites by the proposed technique; the utilization of recycling material is particularly important in the high demanding energy processing sector, as the Al industry. NiAl₂O₄ particles and, in less extent, also SiC particles, can penetrate into the liquid phase present in the thixotropic microstructure within the chip, promoting their disaggregation; reinforcement distribution in the composite depends on appropriate choose of processing parameters.

Abstract: Continuous metal matrix composite strip casting (MMCS-ing) composed of six 0.3-mm diameter annealed bare copper wires in a eutectic SnPb matrix was manufactured by a two-roll melt dragged processing (TRMD-ing) method at a rate of 0.3 m/s. The wires were dragged through a semisolid pool with a fibre contact time of approximately 0.2 s. The required gap between rolls to thixoforge the semisolid material around the wire filaments was approximately 1.4 mm. A successful continuous composite strip casting was achieved with a notably good degree of wire alignment. No cracks were observed at the copper wire/matrix interface. However, regions of porosity occurred in the matrix; their possible formation mechanisms are discussed. The solidification structure of the matrix was analysed, and the analysis results indicated the formation of small globular grains measuring approximately 3 μm in diameter. The specimens were evaluated for their tensile properties and compared with the rule of mixtures. The surface fracture analysis indicated a good matrix/fibre union. MMCS-ing is an economically viable process and has significant advantages over other metal matrix composite (MMC) fabrication methods.

Abstract: The penetration characteristics of tungsten fiber reinforced metallic glass matrix composite with different tungsten fiber spacing were simulated by LS-DYNA programme. It is indicated that J-C constitutive model for describing deformation behaviour of tungsten fiber can accurately reflect the penetration process of the composite. The simulation results show that the composite has obvious self-sharpening behaviour, and its penetration performance is higher than tungsten alloy. The higher penetration performance depends on close-packing of tungsten fibers separated by metallic glass.

Abstract: Wear behaviour of aluminium matrix composites are characterized by pin on disc wear test using various parameters such as sliding distance, sliding speed and load. MMC consists of aluminium alloy (A356) as the matrix material and particulate alumina of 5% and 10% by weight as the reinforcement was fabricated using stir casting. Wear resistance of composites are improved by the presence of reinforcements. Experiments were conducted based on the plan of experiments generated through Taguchi Technique. L₉ orthogonal array was selected for analysis of data. The objective of this investigation is to study the influence of sliding speed, sliding distance, load and weight percentage reinforcement on wear rate of fabricated metal matrix composites.