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.