The focus of the paper is the wear behavior of hybrid aluminum metal matrix composites. The main objective of the investigation is to conduct the wear test at room temperature for both the as-cast and age hardening conditions. Materials chosen for the study are Aluminum 7075 as a matrix, Silicon Carbide and Alumina are the reinforcements. Hybrid metal matrix composites are produced by utilizing stir casting route for 5-15 wt.% silicon carbide and alumina. Microstructural characterization of hybrid aluminum metal matrix composites reveals the homogeneous mixing of reinforcements. It is noticed that the higher composite hardness is obtained due to the raise in weight percentage of the reinforcement up to 10% of hybrid reinforcements. In the T6 heat treatment, there is a gain in hardness by 24 % for optimum percentage of reinforcement i.e. 10 % compare with as-cast composites.

In the present investigation, wear test is conducted on a pin-on-disc device at room temperature for both the age hardening and without age hardening conditions. Al7075 has been chosen as the matrix material. Hybrid aluminum metal matrix composites are produced utilizing stir casting route for enhancing the wear behavior and hardness number. The reinforcement used is silicon carbide with 5, 10, and 15 wt% and alumina as the reinforcement in 5, 10, and 15 wt%. In the aluminum matrix, microstructural characterization reveals homogeneous mixing of reinforcements. This investigation shows that the enhanced wear resistance is due to the increment weight fraction of reinforcement. By raising the sliding speeds, there is a reduction in the rate of wear and it reduces with increment in the sliding distance. With increasing weight fraction, there is decrement in the rate of wear of composites. In general, tribological property enhances because of the addition of the two reinforcements.

ABSTRACT. This paper presents the experimental work carried out on the fracture behavior of aluminium 6061 (Al6061) and graphite particulate composites. The required specimens are prepared using stir casting method with graphite proportions ranging from 3 to 12 % by weight. The fracture behavior of Al6061-graphite particulate composites produced using stir casting method, was investigated by conducting experiments on Universal Testing Machine (UTM). Circumferential Notched Tensile (CNT) specimens were utilized to evaluate the fracture toughness of the composites. From the experiment the fracture toughness KIC= 15.85MPa m 1/2 is obtained for Al6061-9% Graphite. Further, the experimental results revealed that, except 12% graphite, the fracture toughness of Al6061-graphite was observed to increases with an increase in weight percentage of graphite. The experimental results reinforce that Al6061-graphite particulate MMCs are suitable for automotive and aerospace applications requiring high fracture toughness apart from good wear resistance.

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The objective of this research work is to study the fracture behavior of Al6061 with graphite particulate composite produced by the stir casting technique. For the study different composition of the particulate metal matrix composite used is Al6061 with 3, 6, 9, & 12% of graphite particles. Compact Tension (CT) specimens were utilized to determine fracture toughness for different compositions of Al6061-graphite particulate metal matrix composite. Specimens with different composition will be prepared for different crack length to width (a/w) ratios according to the ASTM E-399 standard testing procedure. The maximum fracture toughness was found for Al6061-9%Gr for a/w =0.45 and the value is 16.74 MPa √m.Citation: Doddamani, S., Kaleemulla, M., Fracture toughness investigations of Al6061-Graphite particulate composite using compact specimens, Frattura ed Integrità Strutturale, 41 (2017) 484-490.

In the present investigations, dry sliding wear test is conducted using a pin on disc tribometer at room temperature for both the as-cast and age hardening conditions. Al7075 has chosen as the matrix material. The reinforcement used are particles of silicon carbide and alumina with 5 wt%, 10 wt%, and 15 wt%. Hybrid aluminum metal matrix composites are produced utilizing stir casting route for enhancing the wear behavior. In the aluminum matrix, micro-structural characterization reveals the homogeneous mixing of reinforcements. From the investigation, it is observed that composites containing 10% by weight of silicon carbide and aluminum oxide reinforcements with ageing exhibited superior tribological properties. From the micro-structural study, it has been observed that the generation of the mechanically mixed layer in the hybrid aluminum metal matrix composites will lead to a reduction in wear rate.

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