Fabrication and Characterization of A5083-WC-Al2O3 Surface Composite by Friction Stir Processing

Abstract

In this study, WC-Al2O3 ceramic composite was incorporated into Al5083 to produce a surface composite by friction stir processing (FSP), and the microstructure, hardness and wear properties of Al5083-WC-Al2O3 surface composite were evaluated. Optical microscopy of FSPed samples showed grain refinement in the stir zone. The addition of WC-Al2O3 particles as well as increase in FSP pass number had a considerable effect on grain refinement, and the grain size of Al5083 base metal of 36 µm reduced to 11 µm for Al5083-WC-Al2O3 surface composite after four passes. The SEM observation of the surface composite revealed that the WC-Al2O3 particles distributed homogenously in the matrix and by increasing the FSP passes, the initial agglomerates of mechanochemically synthesized WC-Al2O3 powders could be fractured. Microhardness evaluation showed a substantial improvement by adding WC-Al2O3 particles and increase in FSP pass number. The maximum microhardness value of 101 HV belonged to surface composite after four passes, while the microhardness of the base metal was 65 HV. Wear test results revealed enhanced tribological behavior with a similar trend of microhardness values. Scanning electron microscopy tests revealed both adhesive and abrasive wear mechanisms on the surface of the wear test specimens.