Nanocrystalline Al87Ni8.7Y4.3 and Al90Fe5Gd5 alloys that retain the localized corrosion resistance of the amorphous state

The localized corrosion properties of Al87Ni8.7Y4.3 and Al90Fe5Gd5, were investigated in the amorphous, high strength partially nanocrystalline, and fully crystalline states. The critical pitting potentials and pit growth behaviors of amorphous and nanocrystalline alloys were improved compared to high purity, polycrystalline Al in 0.6 M NaCl solution. Transition metal (TM) and rare earth additions (RE) were retained in solid solution in amorphous alloys and the remaining amorphous matrix of partially nanocrystalline alloys. Substantial TM and RE solute rejection occurred from nano- and microcrystals. Notably, the improved resistance to pitting was retained in the partially nanocrystalline condition, but was completely lost in the fully crystalline alloys. The opportunity exists to create partially nanocrystalline Al-TM-RE alloys of great strength with corrosion resistance equal to their amorphous counterparts. (C) 1999 The Electrochemical Society. S1099-0062(99)02-016-7. All rights reserved.