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In the present study, the experimental results of the mechanical properties of Al6061-Graphite composites presented. The composites containing 6 to 9 wt% of graphite in steps of 3 wt% were prepared using liquid metallurgy route in particular stir casting technique. For each composite, reinforcement particles were preheated to a temperature of 250°C and then dispersed in steps of two into the vortex of molten Al6061 alloy to improve the wettability and distribution. Microstructural characterization was investigated by optical and scanning electron microscopy. Tensile and hardness tests were carried out in order to identify mechanical properties of composites. The results of microstructural study revealed uniform distribution of graphite particles and low porosity in micro composite specimens.The results of this study revealed that as graphite percentage was increased, there was significant increase in ultimate tensile strength, yield strength and ductility, accompanied by a nominal drop in the hardness of the material

In the present work systematic study has been conducted to investigate the matrix properties by introducing nanosize Al2O3 (particle size 100 nm, 0.5–10 wt %) fillers into an epoxy resin. High shear mixing process was employed to disperse the particles into the resin. The experimental results indicated that frictional coefficient and wear rate of epoxy can be reduced at rather low concentration of nanoAl2O3. The lowest specific wear rate 0.7 x 10-4 mm3/Nm is observed for the composites with 1 wt.% which is decreased by 65% as compared to unfilled epoxy. The reinforcement of Al2O3 particles leads to improved mechanical properties of the epoxy composites. The results have been supplemented with scanning electron micrographs to help understand the possible wear mechanisms.

In the present investigation, effect of minor additions of magnesium (Mg) content on the dry sliding wear behavior of A356 alloy has been reported. Alloy composition, normal pressures and sliding distances on A356 alloy has been studied. The worn surfaces were characterized by SEM microanalysis. The results indicate that, the wear rate of A356 alloy increases with increase in normal pressures and sliding distances in all the cases and decreases with 0.7% Mg addition to the A356 alloy. This is due to the change in microstructure resulting in improvement of hardness and strength of the alloy. The worn surface study indicates that, the formation of oxide layer between the mating surfaces during sliding improves sliding wear performance.

In the current investigation an attempt has been made and to produce ceramic Al2O3particulate reinforced 6061Al matrix composites by liquid metallurgy route (stir casting technique) and to study the dry sliding wear properties of the prepared composites. The amount of ceramic Al2O3particulate reinforcement addition was maintained at 9 and 12wt%. During the preparation of each composite the ceramic reinforcements were introduced in a novel way which involves three stage additions of reinforcements during melt stirring. The wear tests were conducted using pin on disc wear testing machine on 6061Al matrix before and after addition of Al2O3reinforcements Wear test results demonstrated the superior wear resistance of the composites over monolithic 6061Al alloy matrix. Key Words: MMC’s, Al2O3particulates, 6061Al, stir-casting

This present paper is an investigation made to study the un-lubricated sliding wear behavior of Al6061 alloy composites reinforced with graphite particulates of size 100-125 μm. The content of graphite in the alloy was varied from 6-9% in steps of 3 wt. %. The liquid metallurgy technique was used to fabricate the composites. A pin-on-disc wear testing machine was used to evaluate the volumetric wear loss, in which a hardened EN32 steel disc was used as the counter face. The results indicated that the volumetric wear loss of the composites was lesser than that of the Al6061 matrix alloy and it further decreased with the increase in graphite content up-to 6 wt.%. For composites containing 9 wt. % of graphite particulates, the volumetric wear loss was more than that of 6wt. % composites, but lesser than base matrix alloy. However, the material loss in terms of wear volume increased with the increase in load and sliding speed, both in case of composites and the alloy.

Aluminum boron carbide metal matrix composites (Al-MMC) have got wide applications in aeronautical and automobile industries due to their excellent mechanical and physical properties. Due to the presence of harder reinforcement particles, machining of these composites is a difficult task. The results of experimental investigation on mechanical and machinability properties of Boron carbide particle (B4Cp) reinforced aluminum metal matrix composites are presented in this paper.The influence of reinforced ratio of 7 wt% of B4Cpon mechanical properties was examined. It was observed that addition of B4Cpreinforcement resulted in improvement in hardness and tensile strengths to the extent of 71% and 38.4% respectively. Fabricated samples were turned on medium duty lathe of 3 kW spidle power with Poly crystalline diamond tool (PCD) of 10 μm particle size at various cutting conditions. The effect of machining parameters, e.g. cutting speed, feed rate and depth of cut on cutting forces and formation of BUE was studied.

In the present work, ternary Al-1Ti-3B master alloys were prepared in an induction furnace via salt route which involves reaction between preheated halide salts (K2TiF6and KBF4) and liquid molten Al. During preparation process parameters such as reaction temperatures of 800, 900, 1000°C and reaction times 45, 60, 75 min. have been used to study the influence of these parameters on the morphology of particles present in the master alloy and inturn on the grain refining efficiency of Al-7Si alloy. The indigenously prepared master alloys were characterized by chemical analysis; particles size analysis, XRD and SEM/EDX microanalysis. Results of particle size analysis suggest that the sizes of the particles present in Al-1Ti-3B master alloys increases with increase in reaction temperature (800-1000°C) and reaction time (45-75 min.). However, the population of the particles having sizes less than 10µm decreases with increase in reaction time and temperature. Further, SEM/EDX studies revealed different morphologies of the particles present in the master alloy when processed at different reaction temperatures and reaction times. Further, the performances of the above-prepared master alloys were assessed for their grain refining efficiency on Al-7Si alloy by DAS analysis and by CACCA studies. Results of grain refinement studies and CACCA studies suggest that, Al-1Ti-3B master alloy prepared at reaction temperature of 800°C with a reaction time of 60min. shows better grain refining performance on Al-7Si alloy when compared to the same master alloy prepared under different processing conditions.

In the present work binary Al-3Ti and Al-3B master alloys were prepared at different reaction temperatures in an induction furnace by the reaction of halide salts like potassium fluoborate and potassium titanium fluoride with liquid molten Al. The indigenously developed master alloys were used for grain refinement studies of Al-7Si alloy and evaluated for their grain refining ability by CACCA studies. The present results suggest that, the reaction temperature influences the size, size distribution and morphology of the intermetallic (Al3Ti in Al-3Ti, and AlB2/AlB12 in Al-3B) particles present in Al-3Ti and Al-3B master alloys. Grain refinement studies of Al-7Si alloy reveal that, Al-3Ti and Al-3B master alloys prepared at 8000C-60 min. have shown better grain refining efficiency on Al- 7Si alloy when compared to the master alloys prepared at 9000C-60 min and 10000C-60 min respectively. In addition, B-rich Al-3B master alloy shows efficient grain refinement than Ti rich Al- 3Ti master alloy.