Corrosion behavior of mechanically alloyed A6005 aluminum alloy composite reinforced with TiB2 nanoparticles

Corrosion susceptibility of the A6005 alloy reinforced with n-TiB2 was studied through electrochemical tests. The mechanical alloying (MA) technique was used as the processing route and a posterior hot extrusion was employed to consolidate the powders. Bulk samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and microhardness tests. The combination of both MA processing and 5 wt% n-TiB2 addition in the aluminum matrix produced 61% increase of microhardness. Electrochemical tests were performed in 3.5 wt% NaCl solution to assess the effect of MA processing and TiB2 presence on corrosion behavior. The corrosion resistance of the samples processed by MA increased slightly compared with the base A6005 alloy. The amorphous Al2O3 phase formed during MA processing was the cause of this increase, providing continuity to the passive layer. Furthermore, the addition of TiB2 on the sample processed by MA did not significantly affect corrosion resistance. Polarization tests confirmed that the reinforced sample had similar i(corr) to that of the unreinforced alloy, and cyclic polarization tests revealed that pit nucleation sites were localized in the interface between Al2O3 and the aluminum matrix.