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Day-to-day life advanced composite materials usage is increasing continuously and replacing the existing monolithic materials. These composite materials are designed and fabricated for human needs with specific applications and also meet the standard requirements. In present study, the agro and industrial wastes derived ceramic reinforcements based Aluminium metal matrix composites, i.e. AA7075/welding slag and AA7075/Rice husk ash are fabricated through liquid metal stir casting route with varying the reinforcement contents from 2 to 12 (wt.%) in the matrix. Mechanical and microstructural characterization of the AA 7075 metal matrix composite were measured and compared to the base material. The results show an improved mechanical strength and high hardness in composites. Impact energy has also significantly improved at higher concentrations of reinforcement particles. Impact energy of the composites increases to 3 J for 9% and 12%, the maximum tensile strength obtained is 173 MPa for 12% Weld Slag MMC. The highest hardness achieved is 98 BHN for 12% Weld Slag MMC. Furthermore, the microstructural results reflect significant grain refinement with stir casting process with good interface characteristics in the matrix and uniform dispersion of agro reinforcement's particles. [ABSTRACT FROM AUTHOR]

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The introduction of new reinforcing materials continues to be investigated to improve the final behaviour of AMCs as well as to avoid some drawbacks of using ceramics as reinforcement. The present work investigates the structure, properties and ability of joining aluminium EN-AW 6061 matrix composite materials reinforced with Ti3Al particles by resistance butt welding as well as composite materials produced by mechanical milling, powder metallurgy and hot extrusion techniques. Mechanically milled and extruded composites show finer and better distribution of reinforcement particles, which leads to better mechanical properties of the obtained products. Finer microstructure improves mechanical properties of obtained composites. The hardness increases twice in the case of mechanically milled composites also, a higher reinforcement content results in higher particle dispersion hardening, for 15 wt.% of intermetallics reinforcement concentration composites reach about 400 MPa UTS. Investigation results of joints show that best hardness and tensile properties of joints can be achieved by altering soft conditions of butt welding process e.g. current flow time 1.2 s and current 1400 A. To improve mechanical properties of butt welding joints age hardening techniques can also be used. [ABSTRACT FROM AUTHOR]

The microscale deformation behaviour of the Al-4.5Cu-2Mg alloy has been studied to understand the influence of various processing routes and conditions, i.e. the gravity casting with and without grain refiner, the rheocast process and the strain induced melt activation (SIMA) process. The micromechanics based simulations have been carried out on the optical microstructures of the alloy by 2D representative volume elements (RVEs) employing two different boundary conditions. Microstructural morphology, such as the grain size, the shape and the volume fraction of α-Al and binary eutectic phases have a significant effect on the stress and strain distribution and the plastic strain localization of the alloy. It is found that the stress and strain distribution became more uniform with increasing the globularity of the α-Al grain and the α-Al phase volume fraction. The simulated RVEs also reveals that the eutectic phase carries more load, but least ductility with respect to the α-Al phase. The SIMA processed alloy contains more uniform stress distribution with less stress localization which ensures better mechanical property than the gravity cast, grain refined and rheocast alloy. [ABSTRACT FROM AUTHOR]

The paper analyses the influence of chemical composition of silicone-based composites on their properties in the aspect of using them as long-term soft denture lining materials. Different concentrations of filler and methylhydrosiloxane-dimethylsiloxane copolymer were used. The filler was introduced into the composite with mechanical mixing combined with ultrasonic homogenization. Scanning electron microscopy was used to investigate the quality of filler dispersion. Shore A hardness, tensile strength, sorption, solubility and tensile bond strength to poly(methyl methacrylate) were measured. Tests show satisfactory results for some experimental composites, which met all the requirements for such materials. [ABSTRACT FROM AUTHOR]

The article presents the results of fatigue life tests and microstructure examinations of A359 alloy matrix composites (F3S.10S and F3S.30S) containing 10 and 30wt% of SiC particles, subjected to multiple remelting by conventional gravity casting. Mechanical characteristics were determined in a modified low cycle fatigue (MLCF) test, enabling rapid estimation of fatigue life and other mechanical parameters in practice of any material. Qualitative and quantitative metallographic examinations were also carried out. The quantitative evaluation of microstructure was performed by computer image analysis. A set of geometrical parameters of the reinforcing particles, pores and eutectic precipitates present in the metal matrix was determined. The relationships between the mechanical parameters, structural characteristics and the number of remelting operations were presented. It was found that up to the fourth remelting, the mechanical characteristics, including fatigue life, are slightly deteriorated but decrease gradually in the subsequent operations of remelting. The observed effect is mainly due to the shrinkage porosity occurring as a result of gravity casting. To eliminate this defect, the use of squeeze casting process was recommended. It has also been shown that multiple remelting can be an easy and economically well-founded alternative to other more expensive recycling methods. [ABSTRACT FROM AUTHOR]