Shape Memory Alloys

These unique metals made from combinations of two or more elements, exhibit hardness and elasticity properties that change radically at distinct temperatures. First observed in 1932 in a Gold-Cadmium alloy (expensive and toxic), interest and research greatly expanded upon the discovery of a Nickel-Titanium (lower cost and non-toxic) alloy in the 1960's.

After alloying and basic processing, SMAs can be formed into a shape (for example, a coil spring), and then set to that shape by a high heat treatment. When cooled, they may be bent, stretched or deformed (within limits) and then with subsequent moderate heating (well below the heat setting temperature), they can recover some or all of the deformation - they move when heated!

Shape memory alloys have found use in everything from space missions (Clementine, Pathfinder and many more) to floral arrangement (animated butterflies, dragonflies and fairys), from arterial stents for restoring blood flow to clogged arteries, to actuators for miniature robots. And cell phone antennas, orthodontic braces and even eyeglasses use SMA wires for their extreme flexibility.

Q: So what is the difference between the all these terms: memory metal, shape memory alloy, Nitinol, Muscle Wires, Flexinol and BioMetal? Are there differences or just marketing hype?

A: Excellent question! All these terms refer to a class of metal alloys having physical properties that change greatly at distinct temperatures, but the details of their performance, ease of use and what you can do with them varies widely.

More that just marketing words, the various terms and names help to convey important information about the different products.

For a comparison, consider the various forms of dough, bread, noodles, croissants and sandwiches. All start as a mix of flour, water and traces of other ingredients, but end up in very different forms for different uses. SMAs

SMA Category
Bread Category
How they compare
Memory Metal
Bread Dough
Like bread dough, you form and bake these raw Ni-Ti wires to your own needs.
Nitinol Spring
These Ni-Ti springs are fully formed and ready to go.
Muscle Wire logo
Wednor logo
A widerange of quality SMA products
Flexinol logo
Prepared and highly processed ready to use.
BioMetal logo
Soba Noodle
Actuator materials like a fine croissant or fresh soba noodles.

Nitinol logo
Nitinol denotes any nickel-titanium shape memory alloy. First developed in the 1960's, the name comes from Ni for nickel, Ti for titanium and NOL for Naval Ordnance Laboratory, its place of discovery.

We provide nitinol wires in their "as drawn" condition for experimenters who wish to form and train their own shapes. In our bread analogy, these wires are raw "dough" since you have to "cook it up" (form and anneal it) to suit your own needs. And just like bread dough, the many parameters of time, temperature and processing can give wide-ranging results.

We also carry nitinol springs that can be easily operated using hot and cold water, or even electric current. These come to you "ready to eat" and need no further processing.

Nitinol also finds use in cell phone antennas, flexible eyeglasses, orthodontic braces, aerospace release mechanisms, medical devices like stents and endoscopic guide wires, greenhouse window openers, hot water scald-prevention valves, magicians tricks and a whole lot more.

Muscle Wire logo
The Muscle Wires brand name includes a wide range of shape memory alloy kits, books and more.

Just as the brand Wonder® represents a wide range of bread, rolls and more, the Muscle Wires name covers a range of shape memory alloy products. The best-selling Muscle Wires Project Book has provided clear and useful introduction to SMAs for tens of thousands of experimenters. The award-winning Space Wings kit and Solar Space Wings kit give easy hands-on experience with electrically activated SMAs. Click for more.

Mondo-tronics has providing shape memory alloy materials and information as well as product design services utilizing these amazing metals to researchers, students, hobbyists and experimenters since 1986!

We've designed SMA devices for a wide range of clients including NASA, Lucasfilm's Industrial Light and Magic, Smithsonian Institute, Boeing, Neiman Marcus, Nature Company, Buckminster Fuller Institute, ShowBiz Pizza Time theaters, science museums, professional magicians (if we told you who they'd make us disappear!) and many others. In 1996 our wire landed on the red planet Mars aboard the Pathfinder Sojourner Rover. Thanks NASA!

Muscle Wires® is a registered trademark of Mondo-tronics, Inc.

Click here for more Muscle Wires Frequently Asked Questions and Answers.

View all MondoTronic Products

Flexinol logo
These highly processed nickel-titanium wires come in a variety of sizes and transition temperatures. They have extensive processing them permit them to operate "right out of the bag" in a wide range of applications. When properly used they can operate for tens of millions of cycles. See the Muscle Wires Project Book for projects using Flexinol wires.

Flexinol® is a registered trademark of Dynalloy Inc.

BioMetal logo
The original highly processed SMA wire. has carrying BioMetal products since we first started business in 1986. Now the line includs many diameters of linear wire, demonstration devices, and their latest innovation, the amazing BMX line of micro helixes - tiny coils of BioMetal wire that give large changes of length with surprisingly high forces.

BioMetal® is a registered trademark of Toki Corporation.