Since the discovery of shape memory in titanium-nickel, a number of inventions have been made having applications in medicine, aerospace, automotive, and consumer products. These devices range in size from meters to micrometers.
Sales are now more than a hundred million USD per year.
Some have been successful in the marketplace, others not, suggesting directions for future development. The first SMAs appeared about 50 years ago, and gained momentum with the discovery at the Naval Ordnance Laboratory in the 1960s of titanium-nickel SMAs. The more common abbreviation is TiNi. This discussion is limited to titanium-nickel based systems. Actuators do not constitute the largest amounts of TiNi in use.