Description
Overview Of Nitinol
Nitinol, a nickel-titanium (Ni-Ti) shape memory alloy (SMA), is a cutting-edge material known for its shape memory effect (SME) and superelasticity. Nitinol powder, derived from this alloy, is a high-performance material with applications spanning medical devices, aerospace, energy, and electronics.
Powder Chemical Composition(wt,-%)
| Parameter | Range/Value | Notes |
| Nickel (Ni) | 53–58% (Standard) | Some variants (e.g., SM-100) may reach 60% Ni for specific applications. |
| Titanium (Ti) | 42–47% (Standard) | Can be adjusted to alter phase transformation temperatures. |
| Third Elements | Fe, Co, Al, Mo, Cu, Zr, Hf | Added to enhance properties (e.g., Mo improves wear resistance). |
| Purity | >99.5% (Medical Grade) | Strictly controlled for biocompatibility. |
Physical Properties
| Parameter | Value/Range | Notes |
| Density | 6.45–6.48 g/cm³ | At 25°C (Ti-55.1%Ni and Ti-55.4%Ni alloys). |
| Melting Temperature | 1240–1310°C | Solidus to liquidus range. |
| Thermal Conductivity | 8.6–18 W/(m·K) | Lower in martensite phase (8.6 W/(m·K)) vs. austenite (18 W/(m·K)). |
| Thermal Expansion | 6.6–11 × 10⁻⁶/°C | Martensite (6.6 × 10⁻⁶/°C) vs. austenite (11 × 10⁻⁶/°C). |
| Electrical Resistivity | 82 × 10⁻⁶ Ω·cm (Austenite) | Martensite phase is slightly higher (76 × 10⁻⁶ Ω·cm). |
Mechanical Properties
| Parameter | Value/Range | Notes |
| Yield Strength | 195–690 MPa | Varies with heat treatment and phase state. |
| Tensile Strength | 550–1200 MPa | Higher values in martensite; medical grades typically ～550–800 MPa. |
| Elongation | 20–25% | Superelastic alloys exhibit up to 8% recoverable strain. |
| Elastic Modulus | 28–83 GPa | Martensite (28–40 GPa) vs. austenite (75–83 GPa). |
| Superelastic Strain | Up to 8% | Stress-induced martensite transformation enables reversible deformation. |
Manufacturing Challenges
– Phase Control: Requires precise heat treatment to balance austenite and martensite phases.
– Defect Minimization: During additive manufacturing (e.g., L-PBF), cracks and porosity must be mitigated via optimized energy density.
– Surface Treatment: Electrolytic polishing improves biocompatibility by forming a TiO₂ passivation layer.
—
Nitinol metal powder represents a transformative material for advanced manufacturing, driven by its unique phase transformation capabilities. As powder processing techniques evolve and surface engineering matures, Nitinol is poised to expand into next-generation applications, including smart materials and sustainable energy systems.
Primary Applications
| Field | Examples | Property Utilized |
| Medical | Stents, orthodontic wires, surgical instruments | Biocompatibility, superelasticity |
| Aerospace | Actuators, sensors, lightweight structures | High strength, corrosion resistance |
| Automotive | Vibration dampers, crash sensors | Shape memory, fatigue resistance |
| Electronics | Temperature controllers, connectors | Thermal sensitivity, conductivity |
