It can straighten teeth and may intercept blood clots. It can stop runaway trains and put out fires. It could help send telephone conservations hundreds of miles.
This miracle worker is a metal called Nitinol, a material with a "memory."
The name explains its origins, both physical and historical: It is alloy of nickel (hence the first syllable of its name) and titanium (the second syllable) developed at the Naval Ordnance Laboratory (third syllable), now called the Naval Surface Weapons Center, in White Oak.
Nitinol and its powers were first uncovered in 1962 by a Navy physicist who was looking for a way to get Navy missiles through the heat of reentry into the atmosphere. Since that time, experiments in both the public and private sectors have revealed a myriad of uses for Nitinol.
The metal derives its powers from "shape memory," which is activated by changes in temperature. This phenomenon is most simply demonstrated by dipping a long, thin strip of Nitinol into a container of ice water. Upon removal, the once rigid strip becomes flexible and can be bent into a "U" shape. Then, upon reaching room temperature, the strip will straighten itself again, returning to the shape it "remembers" as its original state.
The principle behind many of the feats Nitinol can help perform is that, when its shape changes, force is created. Therefore, if overheated bearings on a freight train car begin to cause its axles to fail, a piece of Nitinol in the braking apparatus can be activated by the heat, causing the metal to shorten and release a spring-loaded pin, which in turn starts to put the brakes in motion. A similar reaction takes place when a fire sets off a Nitinol-controlled sprinkler system.
Navy physicist David Goldstein, an ebullient man skilled at explaining the intricacies of the physics of Nitinol and the explorations of its possible uses, says, "The military uses (for Nitinol) are, of course, our prime mission in life--its use in piping systems aboard ship and tubing systems aboard aircraft. We would like to see private industry pick up Nitinol and make usable items for the Navy."
Indeed, private industry has not let the public patent on Nitinol lie dormant. Goldstein said representatives of Raychem Corp., of Menlo Park, Calif., "saw Nitinol being demonstrated at a trade show" and turned around and developed "shrink-fit plastic tubing" for pipes in Navy ships and, later, weldless connectors for the tubing in F-14 fighter planes.
Goldstein and Navy colleague John Tydings released last summer their research on a Nitinol connector for optical fibers, which are planned for use in carrying telephone messages.
"The fiber optic system will carry as much message traffic as a phone cable three inches in diameter," he said. "It's the coming thing in communications . . . .The problem is that you can't use one glass fiber over 650 miles, so if the (connecting) fibers are one-half misaligned, you lose information.
He added that he expects the Nitinol fiber connector to do the trick.
Possible biomedical uses of the metal have spawned testing of a Nitinol blood clot filter which would be inserted into the body in its straight, low-temperature shape and which, when heated by the blood, would return to the filter shape it had when it was originally created. In orthodontistry, braces made of Nitinol have proven less painful than those made of stainless steel.
On the down side, Goldstein notes that previous Department of Energy funding for Nitinol research has "dried up" and that the methods of processing the metal have not yet been perfected. But, as he names individual inventors and their Nitinol projects, Goldstein remains optimistic about the future of the metal with a memory.