Microwave Sintering and Characterisation of Magnesium Alloy AZ61/Carbon Nanotube Composites

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A. D. Akinwekomi
I. O. Oladele
A. Oyetunji


AZ61 magnesium alloy composites reinforced with 2 vol.% of carbon nanotubes (CNTs) were synthesized via the powder metallurgy and microwave (MW) sintering techniques. Using a mechanical alloying (MA) process, the CNTs were incorporated into the AZ61 matrix as the reinforcement phase within 15 hours. The milling medium consisted of steel balls with two different diameters to reduce the size of the AZ61 powder and homogeneously distribute the CNTs in the matrix. The CNTs were not damaged during the MA process as confirmed from the Raman spectra of the composite powder. MW sintering was completed in 10 minutes and the sintered samples had a porosity of ~6%. Further characterization showed that the monolithic sample exhibited 42 Hv, 110 MPa, and 136 MPa for microhardness, compressive yield strength and ultimate compressive strength, respectively. Significant improvements were observed in the properties of the composite sample, which amounted to increments of 68% in microhardness, and ~ 21% and ~56% in yield strength and ultimate compressive strength, respectively. The presence of CNTs in the matrix did not compromise the failure strain of the matrix.

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