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Go to Editorial ManagerThis research is devoted to study the influence of different weight percent concerning to the additions of Ti and Cu on mechanical and tribological properties of AA6061. The composite materials consist of different weight percentage of Ti (0.2, 0.4, and 0.6) wt% and constant weight percentage of Cu (0.2) wt% which were fabricated by liquid metallurgy route technique. Microstructural characterization and phases have been examined by using SEM (scanning electron microscopic).SEM examination showed uniform distribution of nano Ti and Cu in AA6061. The consequences of mechanical tests demonstrated clear enhancement in mechanical properties, such as ultimate tensile strength, yield strength, young modulus, ductility% and hardness at additive percentage of 0.4% Ti+0.2%Cu nano particles incorporated into molten AA6061. Percentage of enhancement ultimate tensile strength is about 73.3%, yield strength about 82.7%, young modulus is about 21.2%, the Vickers hardness about 42.6% and the decreasing in ductility was about 25.2% compared with the metal matrix (AA6061). The wear rate test was performed by using pin on disc rig for both hybrid nano composite and base metal (AA6061) under various loads (10,15and 20) N with sliding speed (1.282) m/sec at a (10) min’s time. The results showed a decrease in wear rate at 0.4%Ti+0.2%Cu compared with the base metal (AA6061). Improvement percentage of wear rate is about 105% at 20 N load.
Aluminum metal matrix composites are widely employed for improving the mechanical properties. Various fabrication routes like liquid state, solid state and liquid-solid state are currently available for producing these materials. The objective of the present work is the fabrication of nano particulate composites AA7075-Al2O3 with different amount of nano particles (20-30 nm) reinforced material Al2O3 (2, 4 and 6 wt%) using stir casting technique at three stirring speeds (300, 850 and 1500 rpm). Tensile tests of these composites were carried-out to obtain the mechanical properties (ultimate strength and ductility). Vickers hardness tests were also performed to obtain the hardness number (VHN) of these materials. All tests were performed at room temperature. The microstructures of the best mechanical properties’ composites were examined for the three stirring speeds. It was revealed that the ultimate strength (?u) and Vickers hardness (VHN) for the composite containing 6 wt% Al2O3 fabricated at 850 rpm show the best properties compared to the other composites fabricated at 300 and 1500 rpm and the matrix. The ?u and VHN were increased by about (36.6 %) and (24.5 %) respectively. Ductility of the strongest composite (6 wt% Al2O3 at 850 rpm speed), however, was the least when compared to other composites and the matrix. With increasing the amount of Al2O3, ?u and VHN, an increasing trend was noticed while the ductility shows a reduction trend. The maximum reduction in ductility occurred for the composite containing 6 wt% Al2O3 obtained at 850 rpm. The ductility of the developed composite was reduced by (23 %). The optical microstructures of unreinforced, as-cast Aluminum alloy AA7075 and 6 wt% Al2O3 composites for all stirring speeds show dendrite microstructure resulting from the casting process, but the composite at the stirring speed of 850 rpm shows a more refined microstructure.
Al2O3 is a major reinforcement in aluminum-based composites, which have been developing rapidly in recent years. The aim of this paper is to investigate the effect of alumina phases and amounts on the physical properties of fabricated Al-Al2O3 composite. Alpha micro and gamma nano of alumina with particle size of 30µm and 20 nm respectively reinforced aluminum matrix of 45 µm. The percentage of reinforcement material were in the range of (5, 10 and 15wt.%) fabricated by powder metallurgy technique. Specimens dimensions were a disc specimens with 11mm diameter and 5 mm thickness. The green density was achieved under compaction pressure of 500MPa, and then sintered under pressure less sintering at 500ºC in a vacuumed tube furnace for two hours Physical properties of the composite samples have been studied such as relative density, sintered density, porosity, microstructure characteristics, particles distribution, agglomeration, grain sizes and granularity accumulation distribution. It has been noticed that at the micro alumina phase, its relative densities are decreased when there is an increase in amount of micro alumina addition, on the contrary in case of nano composites, where the relative density are increasing along with the increase in nano alumina addition. At micro and nano composites, the produced relative densities are less than the pure aluminum relative density. Agglomeration are increasing with the increase in amount of reinforcement, while its more obvious with nano composite. Grain size reduced with the increase in amount of alumina in micro and nano composites, while, the obtained average grain size diameter is less in nano composite than in micro composites. It is obvious from the results that the variation in physical properties and microstructure of Al-Al2O3 composite are depends on both of alumina phases (size) and percentages. At 15wt.% of nano alumina higher relative density and lower porosity will be obtained.