Microstructure and fracture behaviour of two stage stir cast Al6061-SiC composites

Gowri Shankar, M C and Sharma, S S and Kini, Achutha U and Hiremath, Pavan and Gurumurthy, B M (2017) Microstructure and fracture behaviour of two stage stir cast Al6061-SiC composites. Journal of Materials and Environmental Science, 8 (1). pp. 257-263. ISSN 2028-2508

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Abstract

Present work deals with a metal matrix composite (MMC) of Al6061 as matrix and SiC as reinforcing materials. These composites with different amount of SiC are produced by two stage stir casting process. They are then solutionized and aged at different temperature with varying duration. The influence of artificial aging on mechanical properties has been assessed. Microstructural details, macro-hardness and mechanism of fracture behavior after tensile test have been discussed. Fracture surface of the broken tensile sample is studied in details to know failure mode and parameters that influence the crack growth characteristics. It is found that mechanical properties of the MMCs have improved marginally with the addition of SiC reinforcing particulates while after aging this has been improved markedly due to the precipitation of secondary intermetallic phases. It is found that the fracture mode of the pure Al6061 is purely dimple rupture, characteristic of overload failure and this is due to coalescence of micro-voids. While after addition of SiC reinforced particles the fracture mode becomes predominantly de-cohesive rupture mode in addition of dimple and quasi-cleavage rupture mode.

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