Analysis of the corrosion behaviour of Ti49.1Ni50.9 alloy after electrochemical tests

Abstract

This study investigated the surface microstructure of Ti49.1Ni50.9 alloy samples after electrochemical corrosion tests in coarse-grained (CG) and ultrafine-grained (UFG) states was investigated in acid solutions of different concentrations. Increasing the concentration of the solution leads to a significant acceleration of corrosion processes in the alloy Ti49.1Ni50.9 with a high content of Ni relative to the stoichiometry. It was found that the corrosion process proceeded in all investigated states and in all solutions in the form of formation of pittings, as well as with formation of corrosion products when tested in solutions of H2SO4 acid of different concentrations. When tested in HCl solution with increasing concentration of the solution there is a noticeable increase in the size of pits both in coarsegrained, and in the ultrafine-grained state. The maximum size of pittings is reached in the ultrafinegrained state at the concentration of the corrosion solution 3M. On all specimens after testing in H2SO4 solutions corrosion products are observed: in the form of rounded sulfur compounds (1M), in the UFG sample after equal-channel angular pressing with 3M solution concentration corrosion products have rectangular shape.