Corrosion behaviour of vacuum induction-melted Ni-based alloy in sulphuric acid

A vacuum induction-melted (VIM) Ni-based alloy was immersed in 60% H(2)SO(4) solution to investigate its corrosion behaviour and resistance. The results indicate that the microstructure contains a gamma-Ni solid solution + Ni(3)Si particles, dendrite Ni(3)Si, Ni(3)B, Cr(7)C(3), and CrB. The corrosion started at the zones of the gamma-Ni solid solution + Ni(3)Si particles and dendrite Ni(3)Si. These zones transformed to oxide films and protected the alloy from significant attack. However, the pitting corrosion created paths for acid solution and/or SO(4)(2-) to further attack. Therefore, the corrosion rate decreased and then stabilised at a high value as the immersion time increased. (C) 2010 Elsevier Ltd. All rights reserved.