The Corrosion of Nb-Ni Alloys in a KOH Solution

The corrosion behavior of a series of Nb-Ni alloys containing 10 to 98% Ni was investigated in a 25% KOH solution at 25 C. It was found that the alloys containing 10 and 31% Ni, which are composed of δ and γ phases, essentially disintegrate during corrosion in this environment. Disintegration is caused not by dissolution, but by selective hydride formation in the δ phase between the grains of the γ phase. Alloys containing more than 47% Ni have very high corrosion resistance to the solution and do not exhibit rapid disintegration.