TiNi ALLOY SPECIFICATION
The most widely used shape memory material is an alloy of Nickel and Titanium called Nitinol. This particular alloy is commercially available and has the following charcteristics:
- Excellent mechanical properties
- Capable of long fatigue life
- May be joule heated
- High Corrosion Resistance
As an actuator, it is capable of up to 4% strain and 50,000 psi recovery stress, resulting in approximately 1 joule/gm of work output. Nitinol is readily available in the form of wire, rod, and bar stock with transformation temperature in the range of -100° to +100° Celsius.
CuAINi ALLOY SPECIFICATION
SCSMA is a remarkable material manufactured at TiNi Aerospace from Copper, Aluminum, and Nickel (Cu-Al-Ni). This alloy exhibits significantly enhanced performance over commercially available SMAs. These include:
- Significantly greater strain recovery (9% vs. 3%)
- Much higher transition temperature capability (250°C vs.100°C)
- True constant force deflection
- Very narrow loading hysteresis
- Recovery which is 100% repeatable and complete
SCSMAs are manufactured by “growing” as a single crystal from a melt, by a similar method as that used by the semiconductor industry to fabricate silicon boules. The “grown” material is generally fabricated as a rod but can have a range of cross sections (i.e., solid, hollow, flat, or oval). The material can also be subsequently formed into other shapes by traditional fabrication methods such as grinding, machining, or EDM (Electro-Discharge-Machining).
SCSMA raw materials and components are routinely manufactured to support R&D projects. Basic “as drawn” forms include wire, leaf, tube and rod. These may be subsequently machined into more complicated shapes that provide a broad range of functions. These are available in small manufacturing lots with a transition temperature ranging from -150C to +200C.