Although scientists have known about and experimented with SMA's since 1932, it wasn't until 1962 that the materials came out of the laboratory. William Beuhler, working at the US Naval labs, discovered the SMA effect in an alloy of nickel and titanium. At the time the scientific team were trying to develop a heat and corrosive resistant alloy. In the process of creating a corrosive resistant alloy, they created a Shape Memory Alloy (SMA) made of 55% nickel and 45% titanium. This new material was relatively inexpensive and much safer (non-toxic) than previous SMA's.
The team named their new alloy Nitinol (pronounced night-in-all). The name represents its elemental components and place of origin. The "Ni" and "Ti" are the atomic symbols for nickel and titanium. The "NOL" stands for the Naval Ordinance Laboratory where it was discovered.
Although the mixture of nickel to titanium in nitinol is about equal, the smallest change in the ratio of the two compounds has a dramatic effect on the transition temperature of the resulting alloy. For instances, a 1-% difference in the ratio varies the transition temperature from -100 to +100 C. Every company manufacturing nitinol products today must hold the ratio of the components to a precise level to insure a stable and repeatable transition temperature. The nitinol alloy we are experimenting with has a transition temperature of 70C (158F).
Nitinol Products Index Page 2