Characterization of blister formation and pitting of tungsten ion implanted aluminum

the application of W implantation to Al1100 has resulted in improved resistance to pitting corrosion in a neutral pH, 1 wt% NaCl solution. Doses ranging from 3 {times} 10{sup 16} to 9 {times} 10{sup 16} ions/cm{sup 2} greatly enhanced the range of passivity during anodic polarization, and potentiostatic and immersion testing results indicated the implanted W acts to resist the growth of a nucleated pit. Although moderate increases in the pitting potential of Al 1100 (and also 99.9999% pure Al) have been realized, the extremely high pitting potentials achieved by co-sputtering thin films of Al and W were not reproducibly translated to bulk aluminum alloys. This discrepancy can possibly be traced to the morphology of the localized corrosion and breakdown of the passive film on ion-implanted Al, which takes the form of oxide blistering as a forerunner of pit growth.