Effect of TiC precipitation on the corrosion behavior of Monel K500 alloy in 3.5 wt.% NaCl solution

Abstract

The microstructure of Monel K500 alloy was investigated consisting of (Ni-Cu-Al) solid solution matrix distributed with TiC precipitates. The semi-coherent interface was formed between the precipitates and the matrix, which reduced the phase boundary energy, resulting in the preferential corrosion of matrix instead of the interface in 3.5 wt.% NaCl solution. Immersion experiment combined with electrochemical test exhibited the uniform corrosion behavior of the alloy, covered with passivation film consisted of surface polycrystal layer and inner amorphous layer. Moreover, the accumulation of CuO in the film with time, led to generation of microcracks as well as deterioration of corrosion resistance.