Processing, Microstructure and Properties of Hybrid
Metallic and Ceramic Reinforced Aluminium Composites

Abstract

In the present investigation, the combined Ti (micro) and Al2O3 (micro or nano) particles reinforced commercially pure Al matrix composites have been developed via powder metallurgy route. A detailed microstructural characterization and the evaluation of mechanical properties including wear and corrosion behaviour have been carried out. The various combinations were Al+8%Ti , Al+8%micro-Al2O3, Al+8%nano-Al2O3 , Al+8%Ti+8%micro-Al2O3 and Al+8%Ti+8%nano-Al2O3(all vol.%). Microstructural characterization revealed that there is no nano-Al2O3 particles agglomeration in the composites. The interfacial integrity between the matrix and the reinforcements was good. The Al+NA and Al+Ti+NA composites exhibited significant grain refinement following the addition of nano-sized Al2O3 particles. This might be due to the presence of relatively harder Al2O3 particles that inhibits grain growth. The hybrid composites Al+Ti+MA and Al+Ti+NAexhibited a relatively higher hardness values and the same was higher for the later composite.The stress values sustained by all the composites specimens in compression tests during 50% reduction of theirinitial height exhibited a similar trend as hardness.The hybrid composites exhibit a better wear resistance than the composite reinforced with individuals particles owing to their higher hardness as compared to that of the other composites. The short term and long term corrosion behaviour was evaluated by electrochemical corrosion tests. It is observed that the Al+Ti composite exhibited the lowest corrosion rate. The composites reinforced with the ceramic particles alone exhibited higher corrosion rate as compared to the Al+Ti composite. In addition, the Al+NA composites exhibited better corrosion resistance as compared to the Al+MA composite. Further relatively higher corrosion rates were exhibited by the hybrid composites. The same was also confirmed by the long term electrochemical impedance spectroscopy studies.