The corrosion behavior of Ni3(Si,Ti) intermetallic compounds with Al, Cr, and Mo in various acidic solutions

The corrosion behavior of specimens consisting of two regions of a Ni3(Si,Ti) single-phase of L12 structure and two phases of L12 and fcc Ni was examined in 0.5 kmol/m3 HCl, H2SO4 and HNO3. Ni3(Si,Ti) with Cr showed the highest corrosion resistance. The single L12 phase region was preferentially dissolved for all specimens in all solutions. This fact was interpreted in terms of lower corrosion resistance of the region due to the presence of active Al or due to the absence of protective Cr and Mo. Ni3(Si,Ti) with Al and Ni3(Si,Ti) with Cr showed intergranular corrosion in less corrosive HNO3.

► Ni3(Si,Ti) with Cr, Mo and Al consisted of the L12 phase and the two phase region of L12 and Niss.
► Ni3(Si,Ti) with Al had the lowest corrosion resistance in all acidic solutions.
► Ni3(Si,Ti) with Cr had the highest corrosion resistance in H2SO4 and HNO3.
► The preferential dissolution of the L12 single-phase region took place in all acidic solutions.