Nitinol technical properties
Nitinol or Nickel Titanium (also known as NiTi) is in the unique class of shape memory alloys. Nitinol shape memory alloys can be modified to a great extent by changes in composition, mechanical working, and heat treatment.
Nitinol transformation properties
| Transformation temperature | -200 to 110 deg. C | |
| Latent heat of transformation | 5.78 cal/g | |
| Transformation strain (for polycrystalline material) |
for a single cycle | max 8% |
| for 100 cycles | 6% | |
| for 100,000 cycles | 4% | |
| Hysteresis | 30 to 50 deg. C |
Nitinol physical properties
| Melting point | 1300 deg. C (2370 deg. F) | |
| Density | 6.45 g/cu.cm (0.233 lb/cu.in) | |
| Thermal conductivity | austenite | 0.18 W/cm * deg. C (10.4 BTU/ft * hr * deg. F) |
| martensite | 0.086 W/cm * deg. C (5.0 BTU/ft * hr * deg. F) | |
| Coefficient of thermal expansion | austenite | 11.0E-6/deg. C (6.11E-6/deg. F) |
| martensite | 6.6E-6/deg. C (3.67E-6/deg. F) | |
| Specific heat | 0.20 cal/g * deg. C (0.20 BTU/lb * deg. F) | |
| Corrosion performance | excellent |
Electrical and magnetic properties
| Resistivity [resistance = resistivity * length / cross-sectional area] |
austenite | approx. 100 micro-ohms * cm (39 micro-ohms * in) |
| martensite | approx. 80 micro-ohms * cm (32 micro-ohms * in) | |
| Magnetic permeability | < 1.002 | |
| Magnetic susceptibility | 3.0E6 emu/g |
Nitinol mechanical properties
| Young's modulus**** | austenite | approx. 83 GPa (12E6 psi) |
| martensite | approx. 28 to 41 GPa (4E6 to 6E6 psi) | |
| Yield strength | austenite | 195 to 690 MPa (28 to 100 ksi) |
| martensite | 70 to 140 MPa (10 to 20 ksi) | |
| Ultimate tensile strength | fully annealed | 895 MPa (130 ksi) |
| work hardened | 1900 MPa (275 ksi) | |
| Poisson's ratio | 0.33 | |
| Elongation at failure | fully annealed | 25 to 50% |
| work hardened | 5 to 10% | |
| Hot workability | quite good | |
| Cold workability | difficult due to rapid work hardening | |
| Machinability | difficult, abrasive techniques preferred |
Nitinol technical properties legend
** Values listed are for a full martensite to austenite transition.
** Hysteresis can be significantly reduced by partial transformation or ternary alloys.
*** Similar to 300 series stainless steel or titanium
**** Highly nonlinear with temperature