The Analyses of the Corrosion Process of a NI-Ti Shape Memory Alloy in Different Environment

Abstract

In this paper, we investigate the corrosion process of Ni-Ti alloy obtained by the new continius casting method. As the corrosion rate of the material depends on the environment in which the material is located and the corrosion product that slows down the corrosion process over time, in this paper we analyze changes in the base material and the formed corrosion product. This changes were analysed in three different marine environments and at different time intervals of 6 and 12 months. Investigation on the base Ni-Ti alloy, were conducted on base of analyses of the corrosion depth in nm which was measured using the Focus Ion Beam (FIB) method. The linear model was used to calculate the values of corrosion rate during the time of exposure. On the other hand, the corrosion product of the alloy increased over time, resulting in the formation of a corrosive layer on the alloy surface depending on the environment to which it is exposed. The content of the corrosive product was considered using semi-quantitative energy dispersive X-ray (EDX) analysis, and the percentage of oxygen in the corrosive product that appeared on the alloy in all environmental conditions after 6 and 12 months of exposure. As time is raning, corrosion rate is increasing same as percentage of oxygen in each of considered enviroment. Considering results it can be concluded that the formation of the corrosive layer in the sea has a dominant effect on the deceleration of the corrosion process of Ni-Ti alloy, comparing to the all of three considered enviroment.   Received: 11 September 2022 / Accepted: 19 November 2022 / Published: 20 December 2022