Non-medical applications of NiTinol.

Shape memory alloys based on the intermetallic system Nickel-Titanium (NiTi or NiTinol) are widely used in various kinds of industries. At present, the most popular market is medical industry, in which NiTinol finds a perfect environment with a narrow temperature specification ranging from room to body temperature. In this area we find a multitude of different applications, products and important patents. The awareness of engineers in R&D departments of the existence of NiTinol and the knowledge about the material properties has remarkably increased over the years. However, the penetration of other markets in non-medical industries with shape memory alloys, such as automotive industry, did not show a similar development. For many of those applications the use of NiTinol suffers from the fact that the relevant material properties are strongly related to the environmental temperature while some temperature specifications in such markets are remarkably wide. Thus, the number of commercially exploited applications is smaller than in the medical industry with its tightly defined requirements for the working temperature range. The purpose of this paper is to increase the awareness of R&D engineers for use of NiTinol by explaining the strengths and weaknesses of NiTinol, especially by describing and promoting the less well-known properties and effects of the material. These effects do not depend so much on the environmental temperature. In particular, the deformability of the martensitic phase and the linear superelastic effect will be subject of this paper together with some recent applications in non-medical areas.