Effect of heat treatment processes on the corrosion behaviour of NiTi shape memory alloy material in chloride and acidic media

Shape memory alloys (SMAs) are metals that possess sensing and actuating functions which exhibit an exceptional thermo-mechanical behavior which allowing them to completely recover a pre-imposed shape after significant deformations. The consumption of shape memory alloy materials in the consumer and industrial sections however far exceeds the usage in the medical field, and the list of commercial applications is growing at a rapid pace. Nickel Titanium alloys, on account of their shape memory properties, have been proposed for various applications, most of which not involving any foreseeable corrosion problems. However, their corrosion behaviour should be taken into account in case of application in aerospace, sea lines and applications in orthopedic surgery. This work has been carried out in order to improve knowledge on corrosion behavior of Ni-Ti alloys in corrosive environments. The two media (acidic chlorides) have been suggested to Taylor the application of this material towards aerospace where rain water may be the corrosive medium and marine application where environment suffices using both chloride and acidic media. The effect of heat treatments on the corrosion of Ni base super alloys was investigated.