The corrosion behavior of Ni3Al/Ni3V two-phase intermetallic compounds in various acidic solutions

Abstract

The corrosion behavior of the Ni3Al/Ni3V two-phase intermetallic compounds with and without minor elements (Nb, Co, and Cr) to be composed of L12 phase (Ni3Al) and a mixed phase of L1 2 (Ni3Al) and D022 (Ni3V) has been investigated by using an immersion test in 0.5 kmol/m3 HCl, H 2SO4, and HNO3 solutions. The surface morphology was observed before and after the immersion test by scanning electron microscope (SEM). The results were compared to those of the L12 single-phase Ni3(Si,Ti) and austenitic stainless steel type 304. In all acidic solutions, preferential dissolution of (L 1 2 + D 0 22) phase was found in Ni3Al/Ni3V, but no intergranular attack, whereas the attacks took place on Ni3(Si,Ti). The Ni3Al/Ni 3V showed a higher corrosion resistance in HCl solution and a lower resistance in HNO3 solution than Ni3(Si,Ti) and type 304. The addition of the minor elements enhanced corrosion resistance in HNO 3 solution, but not clearly in HCl and H2SO4 solutions. In HCl and H2SO4, their weight losses during the immersion test were almost the same. © 2012 Gadang Priyotomo et al.