Nitinol NiTi
NiTi, near-equiatomic nickel-titanium alloy with nickel nominally 54.5 to 57.0 wt % and titanium as the balance
Also known as ASTM F2063, SE508, 55-Nitinol
Nitinol is a near-equiatomic nickel-titanium alloy, about 55 wt % nickel with titanium as the balance, that recovers a set shape on heating and springs back from large strains.
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Recover its shape
69 to 138 MPa
Carry heat
0.18 and 0.086 W/cm·K
Weight
6.45 g/cm3
Stiffness
75 to 83 GPa austenite
Phase change
−20 to +110 °C
Recipe, share of the weight
- Ni 54.5 to 57%Nickel
- Ti balanceTitanium
Best for
Parts that must change shape or spring back: shape-memory actuators, torque tubes and self-erectable structures, with a 6.45 g/cm3 density and a 75 to 83 GPa austenite modulus
Weakest at
Nickel content and fatigue: the alloy is about half nickel, which an SDS classes with H317 and H351, and its transformation temperature moves with small composition changes
Risk at a glance
- People Moderate. Nickel-driven hazard
- If it fails High. Fatigue cracking in flexed devices
- Corrosion Moderate. Polishing cuts nickel release, and annealing weakens corrosion resistance.
Quick facts: NiTi
| Property | Value | Basis |
|---|---|---|
| Density | 6.45 g/cm³ | 1 sourced value |
| Yield strength | 70 to 690 MPa | 2 sourced values across conditions |
| Young's modulus | 28 to 83 GPa | 2 sourced values across conditions |
| Thermal conductivity | 8.6 to 18 W/(m·K) | 2 sourced values across conditions |
| Thermal expansion (CTE) | 6.6 to 11 ppm/K | 2 sourced values across conditions |
| Melting point | 1,240 to 1,310 °C | 1 sourced value |
| Electrical resistivity | 7.6e-7 to 8.2e-7 Ω·m | 2 sourced values across conditions |
What is the density of Nitinol?
Nitinol has a density of 6.45 g/cm³. The source and test conditions are listed in the properties table on this page.
What is the thermal conductivity of Nitinol?
Nitinol has a thermal conductivity of 8.6 to 18 W/(m·K). The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the coefficient of thermal expansion of Nitinol?
Nitinol has a coefficient of thermal expansion of 6.6 to 11 ppm/K. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the melting point of Nitinol?
Nitinol has a melting point of 1,240 to 1,310 °C. The source and test conditions are listed in the properties table on this page.
What is the yield strength of Nitinol?
Nitinol has a yield strength of 70 to 690 MPa. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What are the other names and codes for Nitinol?
Nitinol is also written as ASTM F2063, SE508, 55-Nitinol. Each code is printed in the source listed beside it in the designations table.
What is Nitinol used for?
Uses recorded in the sources include Torque-tube actuators in nitinol 55 and nickel-titanium-palladium; Self-erectable and expandable structures such as antennas.
Why it exists
Nitinol is a nickel-titanium alloy that can be deformed, hold its shape, and recover it when heated, and that can spring back from large strains. Its austenite phase has an elastic modulus of 75 to 83 GPa, and its martensite phase 28 to 40 GPa, so the same alloy is stiff or soft depending on its phase. Its density is 6.45 g/cm3 at 25 °C for a 55.1 wt % nickel alloy, as the NASA 1972 review reports.
Where it's used
Actuators
NASA Glenn Research Center sprayed NiTi and NiTiPd torque tubes that were tested in torsion as actuators for aircraft and aerospace controls.
Deployable structures
A NASA 1972 review describes self-erectable 55-Nitinol structures, such as antennas, that are compacted in a satellite at launch and expanded later by solar energy.
Recipe
NiTi, near-equiatomic nickel-titanium alloy with nickel nominally 54.5 to 57.0 wt % and titanium as the balance
Nitinol is made by melting nickel and titanium ingot with no other intentional additions, under vacuum or an inert atmosphere (ASTM F2063 abstract). Vacuum arc remelting and vacuum induction melting are the two main methods (Wikipedia). Titanium is so reactive that oxygen or carbon pick-up takes titanium out of the lattice and shifts the transformation temperature (Wikipedia).
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Nickel Ni | 54.5 to 57% | Sets the transformation temperature; typically about 50 to 51 atomic percent, or 55 to 56 weight percent, in the alloy (Wikipedia) |
| Titanium Ti | balance | Balance of the alloy; the reactive element that picks up oxygen and carbon during melting |
Weight shares are as printed in the sources.
What it can do
Recover its shape
69 to 138 MPa
Heating through its transformation range restores the shape it was set in. The martensitic transformation needs 69 to 138 MPa of stress.
Carry heat
0.18 and 0.086 W/cm·K
Thermal conductivity is 0.18 W/cm·K in the austenite phase and 0.086 W/cm·K in the martensite phase, from the Wikipedia property table.
Weight
6.45 g/cm3
Density is 6.45 g/cm3 at 25 °C for the 55.1 wt % nickel alloy in the NASA 1972 review.
Stiffness
75 to 83 GPa austenite
The austenite modulus is 75 to 83 GPa, and the martensite modulus 28 to 40 GPa, a wide swing with phase.
Phase change
−20 to +110 °C
The austenite finish temperature runs from about −20 to +110 °C with composition, and thermal hysteresis is about 20 to 50 °C.
How it compares
The two phases differ the most in this record: austenite has 75 to 83 GPa modulus and 0.18 W/cm·K thermal conductivity, against 28 to 40 GPa and 0.086 W/cm·K for martensite. The rows below compare density, thermal conductivity and thermal expansion, read from the record.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details.
| Measurement | NiTi |
|---|---|
| Thermal behavior and safety | |
| Melting range, 55.1 wt % Ni alloy | 1240 to 1310 °C2 |
| Thermal conductivity, austenite | 0.18 W/cm·K5 |
| Thermal conductivity, martensite | 0.086 W/cm·K6 |
| Thermal hysteresis of the phase transformation | 20 to 50 °C16 |
| Physical and electrical | |
| Density, 55.1 wt % Ni alloy | 6.45 g/cm³1 |
| Electrical resistivity, high-temperature CsCl(B2) form | 82 µΩ·cm3 |
| Electrical resistivity, low-temperature structure | 76 µΩ·cm4 |
| Temperature behavior | |
| Austenite finish temperature Af, upper end of the printed range | < 110 °C15 |
| Other measurements | |
| Coefficient of thermal expansion, austenite | 11 ppm/K7 |
| Coefficient of thermal expansion, martensite | 6.6 ppm/K8 |
| Elastic modulus, austenite | 75 to 83 GPa9 |
| Elastic modulus, martensite | 28 to 40 GPa10 |
| Yield strength, austenite | 195 to 690 MPa11 |
| Yield strength, martensite | 70 to 140 MPa12 |
| Poisson's ratio | 0.33 -13 |
| Stress needed for the martensitic transformation | 69 to 138 MPa14 |
Why choose it, and why not
Good for
- Shape-memory actuators and superelastic parts, with a 6.45 g/cm3 density and a 75 to 83 GPa austenite modulus.
- Medical devices where the NASA and Wikipedia sources rate biocompatibility as high, such as catheters and stents.
- Self-erectable structures that must fold for launch and expand in orbit, per the NASA 1972 review.
Watch out for
- Nickel: the alloy is about half nickel, and the SDS classes it with H317 and H351.
- Fatigue: failures have been observed in the most demanding applications.
- Composition sensitivity: the transformation temperature moves with small composition changes.
- No flight, outgassing or atomic-oxygen data for nitinol was found in this record.
Nitinol is a nickel-titanium alloy whose shape memory and superelasticity come from a reversible phase change. Its density is 6.45 g/cm3, and its phases differ in stiffness, 75 to 83 GPa against 28 to 40 GPa. The record still lacks UNS and EN designations, tensile and fatigue values with temper, and space-environment data, so it is a draft.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Other names and standards
The same grade under other systems, as datasheets and standards print them. Each code was checked against the page it comes from.
| System | Codes |
|---|---|
| ASTM | F2063 |
| Trade name | SE508 (Confluent Medical standard medical-device grade nitinol), 55-Nitinol (named for 55 wt % nickel) |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Density, 55.1 wt % Ni alloy | Measured value cited in the NASA 1972 review, attributed there to Buehler and Wiley (ref. 74) | composition 55.1 weight percent Ni alloytemperature 25 °C | — |
| 2 | Melting range, 55.1 wt % Ni alloy | Range cited in the NASA 1972 review (ref. 74); the review says it is not a true temperature range but reflects uncertainty in the phase diagram, and that NiTi as a congruent melting compound should show a clear melting point | composition 55.1 weight percent Ni alloypressure not stated | — |
| 3 | Electrical resistivity, high-temperature CsCl(B2) form | Value from the resistivity table in the NASA 1972 review, which cites Hanlon et al. (ref. 59) | composition 50.0 atomic percent Tiheat treatment annealed 1 h at 900 °C, water quenchedtemperature extrapolated to about 70 °Cstructure CsCl(B2), high-temperature formunit in source microhm-cm | — |
| 4 | Electrical resistivity, low-temperature structure | Value from the resistivity table in the NASA 1972 review, which cites Hanlon et al. (ref. 59) | composition 50.0 atomic percent Tiheat treatment annealed 1 h at 900 °C, water quenchedtemperature extrapolated to about 70 °Cstructure low-temperature (martensite) structureunit in source microhm-cm | — |
| 5 | Thermal conductivity, austenite | Typical value in the Wikipedia nickel titanium property table (secondary source; the table gives no test standard) | phase austenitecomposition not statedtemper not statedunit in source W/cm·K | — |
| 6 | Thermal conductivity, martensite | Typical value in the Wikipedia nickel titanium property table (secondary source; the table gives no test standard) | phase martensitecomposition not statedtemper not statedunit in source W/cm·K | — |
| 7 | Coefficient of thermal expansion, austenite | Typical value in the Wikipedia nickel titanium property table; the printed unit 10−6 per °C equals ppm per K | phase austeniteunit in source 11 × 10−6/°C | — |
| 8 | Coefficient of thermal expansion, martensite | Typical value in the Wikipedia nickel titanium property table; the printed unit 10−6 per °C equals ppm per K | phase martensiteunit in source 6.6 × 10−6/°C | — |
| 9 | Elastic modulus, austenite | Typical range in the Wikipedia nickel titanium property table (secondary source; no test standard printed) | phase austeniteunit in source 10.9 × 10^6 to 12.0 × 10^6 psi | — |
| 10 | Elastic modulus, martensite | Typical range in the Wikipedia nickel titanium property table (secondary source; no test standard printed) | phase martensiteunit in source 4.1 × 10^6 to 5.8 × 10^6 psi | — |
| 11 | Yield strength, austenite | Typical range in the Wikipedia nickel titanium property table (secondary source; no test standard or temper printed) | phase austenitetemper not statedunit in source 28.3 to 100.1 ksi | — |
| 12 | Yield strength, martensite | Typical range in the Wikipedia nickel titanium property table (secondary source; no test standard or temper printed) | phase martensitetemper not statedunit in source 10 to 20 ksi | — |
| 13 | Poisson's ratio | Typical value in the Wikipedia nickel titanium property table (secondary source) | phase not stated | — |
| 14 | Stress needed for the martensitic transformation | Range printed in the Wikipedia text on the martensitic transformation (secondary source); custom property name, see gaps | phase austenite to martensite under mechanical loadtemperature not stated | — |
| 15 | Austenite finish temperature Af, upper end of the printed range | Upper end of the Af range printed in the Wikipedia composition section (secondary source); custom property name, see gaps | composition varies with composition and processingnote range printed as about −20 to +110 °C; the lower end is not entered because the source writes it with a Unicode minus sign | — |
| 16 | Thermal hysteresis of the phase transformation | Typical range printed in the Wikipedia text on thermal hysteresis (secondary source); custom property name, see gaps | composition depends on the precise composition and processing | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Physiological saline and buffer solutions, static, up to two years (nanostructured NiTi wire, laboratory) | moderate | Polishing cuts nickel release, and annealing weakens corrosion resistance.1 |
| Heat-treated surface of medical nitinol, in tissue and body fluid | low | A thermal oxide layer of TiO2 acts as a barrier against nickel release.2 |
| In vivo, implanted medical device | not rated | In vivo corrosion can change the thermomechanical properties and the biocompatibility of a nitinol device.3 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Physiological saline and buffer solutions, static, up to two years (nanostructured NiTi wire, laboratory) | Mechanical polishing reduced metal ion release by a factor of two to three, while annealing deteriorated corrosion resistance. Mechanically treated samples soaked in saline for two years formed a Ni-free surface with a protective 25 nm titanium oxide film. | basis long-term static immersion, two yearsmaterial nanostructured NiTi wirerating note assistant reading of the abstract; ion release still occurs |
| 2 | Heat-treated surface of medical nitinol, in tissue and body fluid | During heat treatment nitinol forms a stable protective TiO2 layer that acts as a barrier against ion exchange, and nitinol releases nickel more slowly than stainless steel. A thicker oxide layer does not directly reduce nickel release in proportion. | basis medical device literature cited in the Wikipedia article |
| 3 | In vivo, implanted medical device | FDA says the corrosion resistance of nitinol depends strongly on surface processing, and that in vivo corrosion may decrease the safety profile or performance of a device by adversely affecting thermomechanical properties or biocompatibility. The guidance gives no corrosion rate. | basis draft FDA guidance, no rate given |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
Nitinol is about half nickel, and the nitinol alloy SDS classes it with skin sensitisation and carcinogenicity codes. The hazard applies once the material is processed, not in its shipped form.
- Codes on the SDS
- The nitinol alloys SDS lists H317 (allergic skin reaction), H351 (suspected of causing cancer), H372 (organ damage on repeated exposure) and H410 (very toxic to aquatic life), with nickel at 47.6 to 56 % by weight.
- Shipped form
- The same SDS says the product does not present hazards in its shipped form, and that downstream manipulation brings the listed hazards.
If it fails
The sources name three failure routes: fatigue in flexed parts, inclusions in the alloy, and a shift of the transformation temperature with composition or aging.
- Fatigue
- Wikipedia says fatigue failures have been observed in the most demanding applications, such as heart valves and actuators, even though its strain-controlled fatigue performance is described as superior to other metals.
- Composition drift
- Small changes in composition shift the transformation temperature, and aging raises it by taking nickel out of the matrix.
Handling and storage
- Surface
- A polished surface released two to three times less metal ion in the saline study, while annealing weakened corrosion resistance.
- Processing
- Titanium picks up oxygen and carbon in melting, which removes it from the NiTi lattice and shifts the transformation temperature.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Fatigue cracking in flexed deviceshigh severity | Repeated large strains, for example peripheral stents, heart valves and smart actuatorsWikipedia says fatigue failures have been observed in the most demanding applications, although strain-controlled fatigue performance of nitinol is described as superior to all other known metals. |
| Inclusions in the alloymoderate severity | Melting and processing of nickel-titanium ingotInclusions of TiC and Ti2NiOx occur in nitinol, and their size, distribution and type can be controlled only to some extent; the literature disagrees on how far they affect fatigue durability. |
| Shift of the transformation temperaturehigh severity | Small changes in nickel content, oxygen or carbon pick-up from titanium, or agingThe transformation temperature changes significantly with small composition changes, and aging increases it by removing nickel from the matrix, so a part can stop behaving as specified. |
| Nickel release into tissue or solutionmoderate severity | A thin, damaged or annealed surface oxideNickel is an allergen and a possible carcinogen; the saline study found that annealing weakened corrosion resistance and that polishing cut ion release two to three times. |
Handling and storage
- Control the nickel to titanium ratio tightly, because small composition changes shift the transformation temperature.
- Treat the shipped product as not hazardous in that form, but expect H317, H351, H372 and H410 once it is processed, and follow the supplier SDS.
Mitigations
- Mechanical polishing reduced ion release by a factor of two to three in the saline study.
Supply and geography
How common the raw materials are and where they come from.
Nickel, world mine production 2025e (3,900,000 t; Indonesia 2,600,000 t, Philippines 270,000 t, Russia 200,000 t, New Caledonia 140,000 t); shares calculated by Space Mushroom from the printed tonnages
World nickel reserves above 140,000,000 t (USGS 2026, reserves table)
- Top producers (2025)
- Indonesia 66.7%, Philippines 6.9%, Russia 5.1%, New Caledonia 3.6%
- Recycling
- USGS 2026: most secondary nickel was recovered as nickel in stainless-steel scrap, and most recycled nickel went into new alloys.
Titanium sponge metal, world production 2025e (370,000 t; China 260,000 t, Japan 53,000 t, Kazakhstan 16,000 t); shares calculated by Space Mushroom from the printed tonnages
The United States did not produce titanium sponge in 2025; U.S. sponge imports in 2021 to 2024 came from Japan (77 %), Saudi Arabia (13 %) and Kazakhstan (8 %)
- Top producers (2025)
- China 70.3%, Japan 14.3%, Kazakhstan 4.3%
- Recycling
- USGS 2026: consumption data for titanium scrap are limited because voluntary surveys had few responses.
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
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spore: profile
id: nitinol
spore_version: 0.2
family: nickel-titanium-alloys
name: Nitinol
abbreviation: NiTi
role: shape-memory and superelastic alloy for actuators and deployable parts
category: metals
type: shape-memory-alloys
summary: |
Nitinol is a near-equiatomic nickel-titanium alloy, about 55 wt % nickel with titanium as the balance, that recovers a set shape on heating and springs back from large strains. A NASA 1972 review gives its density as 6.45 g/cm3 at 25 °C for a 55.1 wt % nickel alloy, and a melting range of 1240 to 1310 °C. Its two phases differ widely in stiffness: the austenite phase has an elastic modulus of 75 to 83 GPa and the martensite phase 28 to 40 GPa.
best_for: 'Parts that must change shape or spring back: shape-memory actuators, torque tubes and self-erectable structures, with a 6.45 g/cm3 density and a 75 to 83 GPa austenite modulus'
weakest_at: 'Nickel content and fatigue: the alloy is about half nickel, which an SDS classes with H317 and H351, and its transformation temperature moves with small composition changes'
identity:
formula: NiTi, near-equiatomic nickel-titanium alloy with nickel nominally 54.5 to 57.0 wt % and titanium as the balance
source: astm
where: 'Abstract: nominally 54.5 % to 57.0 % nickel, made from nickel and titanium with no other intentional alloy additions'
designations:
- system: ASTM
code: F2063
note: wrought nickel-titanium shape memory alloys for medical devices and surgical implants
source: astm
where: Title and abstract of the F2063-26 store page
- system: Trade name
code: SE508
note: Confluent Medical standard medical-device grade nitinol
source: confluent
where: Nitinol material page, grade list SE508 and SE508 ELI
- system: Trade name
code: 55-Nitinol
note: named for 55 wt % nickel
source: nasa1972
where: Title and introduction, 55-Nitinol series
tags:
environments: []
stresses: []
applications:
- mechanisms
- structures
properties:
- benchmark: density
label: Density, 55.1 wt % Ni alloy
value: 6.45
unit: g/cm3
scope: material
conditions:
composition: 55.1 weight percent Ni alloy
temperature: 25 °C
method: Measured value cited in the NASA 1972 review, attributed there to Buehler and Wiley (ref. 74)
status: ground
source: nasa1972
where: Density section, first paragraph
- benchmark: melting_point
label: Melting range, 55.1 wt % Ni alloy
value: 1240
value_high: 1310
bound: range
unit: °C
scope: material
conditions:
composition: 55.1 weight percent Ni alloy
pressure: not stated
method: Range cited in the NASA 1972 review (ref. 74); the review says it is not a true temperature range but reflects uncertainty in the phase diagram, and that NiTi as a congruent melting compound should show a clear melting point
status: ground
source: nasa1972
where: Melting Point section, first paragraph
- benchmark: electrical_resistivity
label: Electrical resistivity, high-temperature CsCl(B2) form
value: 82
unit: µΩ·cm
scope: material
conditions:
composition: 50.0 atomic percent Ti
heat_treatment: annealed 1 h at 900 °C, water quenched
temperature: extrapolated to about 70 °C
structure: CsCl(B2), high-temperature form
unit_in_source: microhm-cm
method: Value from the resistivity table in the NASA 1972 review, which cites Hanlon et al. (ref. 59)
status: ground
source: nasa1972
where: Electrical Resistivity section, table column CsCl(B2) structure, first row
- benchmark: electrical_resistivity
label: Electrical resistivity, low-temperature structure
value: 76
unit: µΩ·cm
scope: material
conditions:
composition: 50.0 atomic percent Ti
heat_treatment: annealed 1 h at 900 °C, water quenched
temperature: extrapolated to about 70 °C
structure: low-temperature (martensite) structure
unit_in_source: microhm-cm
method: Value from the resistivity table in the NASA 1972 review, which cites Hanlon et al. (ref. 59)
status: ground
source: nasa1972
where: Electrical Resistivity section, table column Low-temperature structure, first row
- benchmark: thermal_conductivity
label: Thermal conductivity, austenite
value: 0.18
unit: W/cm·K
scope: material
conditions:
phase: austenite
composition: not stated
temper: not stated
unit_in_source: W/cm·K
method: Typical value in the Wikipedia nickel titanium property table (secondary source; the table gives no test standard)
status: ground
source: wiki
where: Infobox material properties table, row Thermal conductivity (austenite)
- benchmark: thermal_conductivity
label: Thermal conductivity, martensite
value: 0.086
unit: W/cm·K
scope: material
conditions:
phase: martensite
composition: not stated
temper: not stated
unit_in_source: W/cm·K
method: Typical value in the Wikipedia nickel titanium property table (secondary source; the table gives no test standard)
status: ground
source: wiki
where: Infobox material properties table, row Thermal conductivity (martensite)
- benchmark: cte
label: Coefficient of thermal expansion, austenite
value: 11
unit: ppm/K
scope: material
conditions:
phase: austenite
unit_in_source: 11 × 10−6/°C
method: Typical value in the Wikipedia nickel titanium property table; the printed unit 10−6 per °C equals ppm per K
status: ground
source: wiki
where: Infobox material properties table, row Coefficient of thermal expansion (austenite)
- benchmark: cte
label: Coefficient of thermal expansion, martensite
value: 6.6
unit: ppm/K
scope: material
conditions:
phase: martensite
unit_in_source: 6.6 × 10−6/°C
method: Typical value in the Wikipedia nickel titanium property table; the printed unit 10−6 per °C equals ppm per K
status: ground
source: wiki
where: Infobox material properties table, row Coefficient of thermal expansion (martensite)
- benchmark: elastic_modulus
label: Elastic modulus, austenite
value: 75
value_high: 83
bound: range
unit: GPa
scope: material
conditions:
phase: austenite
unit_in_source: 10.9 × 10^6 to 12.0 × 10^6 psi
method: Typical range in the Wikipedia nickel titanium property table (secondary source; no test standard printed)
status: ground
source: wiki
where: Infobox material properties table, row Elastic modulus (austenite)
- benchmark: elastic_modulus
label: Elastic modulus, martensite
value: 28
value_high: 40
bound: range
unit: GPa
scope: material
conditions:
phase: martensite
unit_in_source: 4.1 × 10^6 to 5.8 × 10^6 psi
method: Typical range in the Wikipedia nickel titanium property table (secondary source; no test standard printed)
status: ground
source: wiki
where: Infobox material properties table, row Elastic modulus (martensite)
- benchmark: yield_strength
label: Yield strength, austenite
value: 195
value_high: 690
bound: range
unit: MPa
scope: material
conditions:
phase: austenite
temper: not stated
unit_in_source: 28.3 to 100.1 ksi
method: Typical range in the Wikipedia nickel titanium property table (secondary source; no test standard or temper printed)
status: ground
source: wiki
where: Infobox material properties table, row Yield strength (austenite)
- benchmark: yield_strength
label: Yield strength, martensite
value: 70
value_high: 140
bound: range
unit: MPa
scope: material
conditions:
phase: martensite
temper: not stated
unit_in_source: 10 to 20 ksi
method: Typical range in the Wikipedia nickel titanium property table (secondary source; no test standard or temper printed)
status: ground
source: wiki
where: Infobox material properties table, row Yield strength (martensite)
- benchmark: poissons_ratio
label: Poisson's ratio
value: 0.33
unit: '-'
scope: material
conditions:
phase: not stated
method: Typical value in the Wikipedia nickel titanium property table (secondary source)
status: ground
source: wiki
where: Infobox material properties table, row Poisson's ratio
- benchmark: martensite_transformation_stress
label: Stress needed for the martensitic transformation
value: 69
value_high: 138
bound: range
unit: MPa
scope: material
conditions:
phase: austenite to martensite under mechanical load
temperature: not stated
method: Range printed in the Wikipedia text on the martensitic transformation (secondary source); custom property name, see gaps
status: ground
source: wiki
where: Section on the martensitic transformation, sentence beginning with the transformation requiring 69 to 138 MPa
- benchmark: austenite_finish_temperature
label: Austenite finish temperature Af, upper end of the printed range
value: 110
bound: upper
unit: °C
scope: material
conditions:
composition: varies with composition and processing
note: range printed as about −20 to +110 °C; the lower end is not entered because the source writes it with a Unicode minus sign
method: Upper end of the Af range printed in the Wikipedia composition section (secondary source); custom property name, see gaps
status: ground
source: wiki
where: Composition section, sentence beginning with Transformation temperatures in nitinol can be controlled
- benchmark: thermal_hysteresis
label: Thermal hysteresis of the phase transformation
value: 20
value_high: 50
bound: range
unit: °C
scope: material
conditions:
composition: depends on the precise composition and processing
method: Typical range printed in the Wikipedia text on thermal hysteresis (secondary source); custom property name, see gaps
status: ground
source: wiki
where: Thermal hysteresis paragraph, about 20 to 50 °C
corrosion:
- environment: Physiological saline and buffer solutions, static, up to two years (nanostructured NiTi wire, laboratory)
headline: Polishing cuts nickel release, and annealing weakens corrosion resistance.
effect: Mechanical polishing reduced metal ion release by a factor of two to three, while annealing deteriorated corrosion resistance. Mechanically treated samples soaked in saline for two years formed a Ni-free surface with a protective 25 nm titanium oxide film.
rating: moderate
conditions:
basis: long-term static immersion, two years
material: nanostructured NiTi wire
rating_note: assistant reading of the abstract; ion release still occurs
source: pmc6915
where: Abstract
- environment: Heat-treated surface of medical nitinol, in tissue and body fluid
headline: A thermal oxide layer of TiO2 acts as a barrier against nickel release.
effect: During heat treatment nitinol forms a stable protective TiO2 layer that acts as a barrier against ion exchange, and nitinol releases nickel more slowly than stainless steel. A thicker oxide layer does not directly reduce nickel release in proportion.
rating: low
conditions:
basis: medical device literature cited in the Wikipedia article
source: wiki
where: Nickel release paragraph in the Biocompatible and biomedical applications section
- environment: In vivo, implanted medical device
headline: In vivo corrosion can change the thermomechanical properties and the biocompatibility of a nitinol device.
effect: FDA says the corrosion resistance of nitinol depends strongly on surface processing, and that in vivo corrosion may decrease the safety profile or performance of a device by adversely affecting thermomechanical properties or biocompatibility. The guidance gives no corrosion rate.
rating: unknown
conditions:
basis: draft FDA guidance, no rate given
source: fda
where: Introduction, corrosion paragraph
risks:
hazards:
- text: 'Nitinol alloys SDS (2026): skin sensitisation Category 1 (H317, may cause an allergic skin reaction), carcinogenicity Category 2 (H351, suspected of causing cancer), STOT repeated exposure Category 1 (H372) and chronic aquatic hazard Category 1 (H410). Signal word Danger. Nickel is listed at 47.6 – 56 % by weight in the composition table.'
ghs:
- H317
- H351
- H372
- H410
source: sds-nitinol
where: Sections 2 and 3, hazard statements and composition table
- text: The same SDS says the product does not present hazards in its shipped form, and that downstream manipulation of the material gives the hazards listed.
ghs: []
source: sds-nitinol
where: Section 2 hazard summary
failure_risks:
- mode: Fatigue cracking in flexed devices
trigger: Repeated large strains, for example peripheral stents, heart valves and smart actuators
consequence: Wikipedia says fatigue failures have been observed in the most demanding applications, although strain-controlled fatigue performance of nitinol is described as superior to all other known metals.
severity: high
source: wiki
where: Fatigue section
- mode: Inclusions in the alloy
trigger: Melting and processing of nickel-titanium ingot
consequence: Inclusions of TiC and Ti2NiOx occur in nitinol, and their size, distribution and type can be controlled only to some extent; the literature disagrees on how far they affect fatigue durability.
severity: moderate
source: wiki
where: Fatigue and inclusions discussion
- mode: Shift of the transformation temperature
trigger: Small changes in nickel content, oxygen or carbon pick-up from titanium, or aging
consequence: The transformation temperature changes significantly with small composition changes, and aging increases it by removing nickel from the matrix, so a part can stop behaving as specified.
severity: high
source: wiki
where: Composition and Heat treatment sections
- mode: Nickel release into tissue or solution
trigger: A thin, damaged or annealed surface oxide
consequence: Nickel is an allergen and a possible carcinogen; the saline study found that annealing weakened corrosion resistance and that polishing cut ion release two to three times.
severity: moderate
source: pmc6915
where: Abstract
side_effects: []
handling:
- text: Control the nickel to titanium ratio tightly, because small composition changes shift the transformation temperature.
source: wiki
where: Composition section
- text: Treat the shipped product as not hazardous in that form, but expect H317, H351, H372 and H410 once it is processed, and follow the supplier SDS.
source: sds-nitinol
where: Section 2 hazard summary
mitigations:
- text: Mechanical polishing reduced ion release by a factor of two to three in the saline study.
source: pmc6915
where: Abstract
uses:
- application: mechanisms
device: Torque-tube actuators in nitinol 55 and nickel-titanium-palladium
example: NASA Glenn Research Center vacuum plasma sprayed NiTi torque tubes and tested them in torsion, for actuation in aircraft and aerospace controls.
source: glenn2008
where: Abstract
- application: structures
device: Self-erectable and expandable structures such as antennas
example: A NASA 1972 review says 55-Nitinol structures such as antennas could be compacted in a satellite during launch and later expanded to full size by solar energy.
source: nasa1972
where: Chapter on applications for 55-Nitinol, paragraph beginning with another type of application
supply:
- subject: Nickel, world mine production 2025e (3,900,000 t; Indonesia 2,600,000 t, Philippines 270,000 t, Russia 200,000 t, New Caledonia 140,000 t); shares calculated by Space Mushroom from the printed tonnages
abundance: World nickel reserves above 140,000,000 t (USGS 2026, reserves table)
producers:
- country: Indonesia
share_percent: 66.7
year: 2025
- country: Philippines
share_percent: 6.9
year: 2025
- country: Russia
share_percent: 5.1
year: 2025
- country: New Caledonia
share_percent: 3.6
year: 2025
critical_lists: []
recycling: 'USGS 2026: most secondary nickel was recovered as nickel in stainless-steel scrap, and most recycled nickel went into new alloys.'
substitutes: []
source: usgs-ni
where: World Mine Production and Reserves table, columns 2024 and 2025e
- subject: Titanium sponge metal, world production 2025e (370,000 t; China 260,000 t, Japan 53,000 t, Kazakhstan 16,000 t); shares calculated by Space Mushroom from the printed tonnages
abundance: The United States did not produce titanium sponge in 2025; U.S. sponge imports in 2021 to 2024 came from Japan (77 %), Saudi Arabia (13 %) and Kazakhstan (8 %)
producers:
- country: China
share_percent: 70.3
year: 2025
- country: Japan
share_percent: 14.3
year: 2025
- country: Kazakhstan
share_percent: 4.3
year: 2025
critical_lists: []
recycling: 'USGS 2026: consumption data for titanium scrap are limited because voluntary surveys had few responses.'
substitutes: []
source: usgs-ti
where: Domestic Production and Use, Import Sources, and World Sponge Metal Production table
documents:
- title: 'Wikipedia: Nickel titanium (nitinol composition, phases, property table, fatigue and biomedical use)'
type: database
url: https://en.wikipedia.org/wiki/Nickel_titanium
- title: 'NASA NTRS 19720022818: 55-Nitinol, the alloy with a memory (1972 review)'
type: report
url: https://ntrs.nasa.gov/api/citations/19720022818/downloads/19720022818.pdf
year: 1972
- title: ASTM F2063 Standard Specification for Wrought Nickel-Titanium Shape Memory Alloys for Medical Devices and Surgical Implants (store page)
type: standard
url: https://store.astm.org/f2063-26.html
- title: Confluent Medical, Nitinol Tubing and Wire and Nitinol material page
type: datasheet
url: https://confluentmedical.com/capabilities/nitinol-material/
- title: 'FDA draft guidance: Nitinol Technical Guidance (2019)'
type: report
url: https://www.fda.gov/media/123272/download
year: 2019
- title: 'USGS Mineral Commodity Summaries 2026: Nickel'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
year: 2026
- title: 'USGS Mineral Commodity Summaries 2026: Titanium'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-titanium.pdf
year: 2026
- title: Resonetics safety data sheet, Nitinol Alloys (2026)
type: sds
url: https://resonetics.com/wp-content/uploads/2024/12/SDS-Nitinol-Alloys-6-23-2026.pdf
year: 2026
- title: Ion release and surface characterization of nanostructured nitinol during long-term testing (PMC6915401, 2019)
type: paper
url: https://pmc.ncbi.nlm.nih.gov/articles/PMC6915401
year: 2019
- title: Spray forming of NiTi and NiTiPd shape-memory alloys (NASA NTRS 20080047469, 2008)
type: paper
url: https://ntrs.nasa.gov/api/citations/20080047469/downloads/20080047469.pdf
year: 2008
gaps:
- The Johnson Matthey nitinol technical properties page returned a 404 to the fetch tool, and its raw page held no property text, so no value was taken from Johnson Matthey in this run.
- No UNS, EN, EN name, W.Nr., JIS or AMS designation for nitinol was printed in a source read in this run, so none is listed. The ASTM F2063 code and the SE508 and 55-Nitinol names are the only designations recorded.
- Transformation temperatures Ms, Mf, As and Af at a stated composition and heat treatment were not read as table values; only the Wikipedia Af range (about −20 to +110 °C, upper end entered) and the hysteresis range are recorded.
- No ultimate tensile strength, elongation, fatigue limit or superelastic strain value with a stated temper or form was read in this run; the Wikipedia yield figures are phase-based with no temper stated.
- No atomic oxygen erosion, outgassing or flight result for nitinol was found in a source read in this run.
- 'No corrosion rate in micrometres per year or nickel release in micrograms per square centimetre was extracted: the PMC Table 2 ion concentrations did not parse cleanly from the HTML.'
- 'Critical-mineral list status for nickel and titanium was not confirmed: the USGS nickel text mentions critical minerals only in the context of an executive order on seabed minerals, and the titanium text gives no list.'
- Torque, actuation force and transformation values from the NASA Glenn 2008 paper were not extracted; the paper was read as an abstract and as a use reference only.
- 'Custom property names used because no canonical name exists: martensite_transformation_stress, austenite_finish_temperature and thermal_hysteresis.'
- FDA Nitinol Technical Guidance read is a 2019 draft, not a final guidance.
- Wikipedia property values are secondary and carry no test standard or temper; they are recorded as typical values.
sources:
wiki:
title: Nickel titanium (Nitinol), Wikipedia
url: https://en.wikipedia.org/wiki/Nickel_titanium
kind: web
license: CC BY-SA 4.0 (cited, not reproduced)
nasa1972:
title: 55-Nitinol, the alloy with a memory (NASA NTRS 19720022818, 1972 review)
id: NTRS 19720022818
url: https://ntrs.nasa.gov/api/citations/19720022818/downloads/19720022818.pdf
year: 1972
kind: report
license: public domain (NASA)
astm:
title: ASTM F2063, Standard Specification for Wrought Nickel-Titanium Shape Memory Alloys for Medical Devices and Surgical Implants (store page, F2063-26)
id: ASTM F2063-26
url: https://store.astm.org/f2063-26.html
kind: standard
license: standard text not reproduced; abstract cited
confluent:
title: Confluent Medical, Nitinol Tubing and Wire (grades SE508, SE508 ELI, SE510)
url: https://confluentmedical.com/capabilities/nitinol-material/
kind: datasheet
license: manufacturer web page (cited, not reproduced)
fda:
title: FDA draft guidance, Nitinol Technical Guidance (issued 19 April 2019)
url: https://www.fda.gov/media/123272/download
year: 2019
kind: report
license: US government work (cited, not reproduced)
usgs-ni:
title: Mineral Commodity Summaries 2026, Nickel (USGS, February 2026)
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-ti:
title: Mineral Commodity Summaries 2026, Titanium (USGS, February 2026)
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-titanium.pdf
year: 2026
kind: report
license: public domain (USGS)
sds-nitinol:
title: Safety data sheet, Nitinol Alloys (Resonetics, 29 CFR 1910.1200 format, 2026)
url: https://resonetics.com/wp-content/uploads/2024/12/SDS-Nitinol-Alloys-6-23-2026.pdf
year: 2026
kind: datasheet
license: manufacturer safety data sheet (cited, not reproduced)
pmc6915:
title: Ion release and surface characterization of nanostructured nitinol during long-term testing
url: https://pmc.ncbi.nlm.nih.gov/articles/PMC6915401
year: 2019
kind: paper
license: open access (cited, not reproduced)
glenn2008:
title: Spray forming of NiTi and NiTiPd shape-memory alloys (NASA Glenn, NTRS 20080047469)
id: NTRS 20080047469
url: https://ntrs.nasa.gov/api/citations/20080047469/downloads/20080047469.pdf
year: 2008
kind: paper
license: public domain (NASA)
license: CC-BY-4.0
updated: '2026-10-25'
review:
status: draft
method: assistant
checked_values: 16
unreachable: 1
caveats: 4
note: 'Values were read by an AI assistant on 2026-10-25 from the pages and PDFs named in each entry. Unreachable: the Johnson Matthey technical page. Caveats: Wikipedia property values are secondary and carry no temper or test standard; the Af upper bound is entered alone; the SDS nickel range is wide; the saline study is on nanostructured wire, not a standard grade.'
story:
risk_groups:
- title: For people
lead: Nitinol is about half nickel, and the nitinol alloy SDS classes it with skin sensitisation and carcinogenicity codes. The hazard applies once the material is processed, not in its shipped form.
level: 2
verdict: Nickel-driven hazard
points:
- label: Codes on the SDS
line: The nitinol alloys SDS lists H317 (allergic skin reaction), H351 (suspected of causing cancer), H372 (organ damage on repeated exposure) and H410 (very toxic to aquatic life), with nickel at 47.6 to 56 % by weight.
- label: Shipped form
line: The same SDS says the product does not present hazards in its shipped form, and that downstream manipulation brings the listed hazards.
- title: If it fails
lead: 'The sources name three failure routes: fatigue in flexed parts, inclusions in the alloy, and a shift of the transformation temperature with composition or aging.'
level: 2
verdict: Fatigue and composition
points:
- label: Fatigue
line: Wikipedia says fatigue failures have been observed in the most demanding applications, such as heart valves and actuators, even though its strain-controlled fatigue performance is described as superior to other metals.
- label: Composition drift
line: Small changes in composition shift the transformation temperature, and aging raises it by taking nickel out of the matrix.
- title: Handling and storage
points:
- label: Surface
line: A polished surface released two to three times less metal ion in the saline study, while annealing weakened corrosion resistance.
- label: Processing
line: Titanium picks up oxygen and carbon in melting, which removes it from the NiTi lattice and shifts the transformation temperature.
why: Nitinol is a nickel-titanium alloy that can be deformed, hold its shape, and recover it when heated, and that can spring back from large strains. Its austenite phase has an elastic modulus of 75 to 83 GPa, and its martensite phase 28 to 40 GPa, so the same alloy is stiff or soft depending on its phase. Its density is 6.45 g/cm3 at 25 °C for a 55.1 wt % nickel alloy, as the NASA 1972 review reports.
uses:
- where: Actuators
line: NASA Glenn Research Center sprayed NiTi and NiTiPd torque tubes that were tested in torsion as actuators for aircraft and aerospace controls.
- where: Deployable structures
line: A NASA 1972 review describes self-erectable 55-Nitinol structures, such as antennas, that are compacted in a satellite at launch and expanded later by solar energy.
can_do:
- label: Recover its shape
line: Heating through its transformation range restores the shape it was set in. The martensitic transformation needs 69 to 138 MPa of stress.
value: 69 to 138 MPa
- label: Carry heat
line: Thermal conductivity is 0.18 W/cm·K in the austenite phase and 0.086 W/cm·K in the martensite phase, from the Wikipedia property table.
value: 0.18 and 0.086 W/cm·K
- label: Weight
line: Density is 6.45 g/cm3 at 25 °C for the 55.1 wt % nickel alloy in the NASA 1972 review.
value: 6.45 g/cm3
- label: Stiffness
line: The austenite modulus is 75 to 83 GPa, and the martensite modulus 28 to 40 GPa, a wide swing with phase.
value: 75 to 83 GPa austenite
- label: Phase change
line: The austenite finish temperature runs from about −20 to +110 °C with composition, and thermal hysteresis is about 20 to 50 °C.
value: −20 to +110 °C
compare: 'The two phases differ the most in this record: austenite has 75 to 83 GPa modulus and 0.18 W/cm·K thermal conductivity, against 28 to 40 GPa and 0.086 W/cm·K for martensite. The rows below compare density, thermal conductivity and thermal expansion, read from the record.'
compare_rows:
- label: Density
benchmark: density
- label: Thermal conductivity
benchmark: thermal_conductivity
- label: Thermal expansion
benchmark: cte
handling:
- Control the nickel to titanium ratio tightly, because small composition changes shift the transformation temperature.
- Treat the shipped product as not hazardous in that form, but expect H317, H351, H372 and H410 once it is processed, and follow the supplier SDS.
- Polishing reduces nickel release, while annealing weakens corrosion resistance in the saline study.
good_for:
- Shape-memory actuators and superelastic parts, with a 6.45 g/cm3 density and a 75 to 83 GPa austenite modulus.
- Medical devices where the NASA and Wikipedia sources rate biocompatibility as high, such as catheters and stents.
- Self-erectable structures that must fold for launch and expand in orbit, per the NASA 1972 review.
watch_out:
- 'Nickel: the alloy is about half nickel, and the SDS classes it with H317 and H351.'
- 'Fatigue: failures have been observed in the most demanding applications.'
- 'Composition sensitivity: the transformation temperature moves with small composition changes.'
- No flight, outgassing or atomic-oxygen data for nitinol was found in this record.
verdict: Nitinol is a nickel-titanium alloy whose shape memory and superelasticity come from a reversible phase change. Its density is 6.45 g/cm3, and its phases differ in stiffness, 75 to 83 GPa against 28 to 40 GPa. The record still lacks UNS and EN designations, tensile and fatigue values with temper, and space-environment data, so it is a draft.
recipe:
line: Nitinol is made by melting nickel and titanium ingot with no other intentional additions, under vacuum or an inert atmosphere (ASTM F2063 abstract). Vacuum arc remelting and vacuum induction melting are the two main methods (Wikipedia). Titanium is so reactive that oxygen or carbon pick-up takes titanium out of the lattice and shifts the transformation temperature (Wikipedia).
parts:
- name: Nickel
symbol: Ni
role: Sets the transformation temperature; typically about 50 to 51 atomic percent, or 55 to 56 weight percent, in the alloy (Wikipedia)
share_percent: 54.5
share_high: 57
source: astm
where: 'Abstract: nominally 54.5 % to 57.0 % nickel'
- name: Titanium
symbol: Ti
role: Balance of the alloy; the reactive element that picks up oxygen and carbon during melting
share_note: balance
source: astm
where: 'Abstract: no other intentional alloy additions'
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
| # | Source | Type | Year | Used for |
|---|---|---|---|---|
| Nickel titanium (Nitinol), Wikipedia | web | 17 values | ||
| 55-Nitinol, the alloy with a memory (NASA NTRS 19720022818, 1972 review) | report | 1972 | 5 values | |
| ASTM F2063, Standard Specification for Wrought Nickel-Titanium Shape Memory Alloys for Medical Devices and Surgical Implants (store page, F2063-26) | standard | 1 value | ||
| Confluent Medical, Nitinol Tubing and Wire (grades SE508, SE508 ELI, SE510) | datasheet | 0 values | ||
| FDA draft guidance, Nitinol Technical Guidance (issued 19 April 2019) | report | 2019 | 1 value | |
| Mineral Commodity Summaries 2026, Nickel (USGS, February 2026) | report | 2026 | 1 value | |
| Mineral Commodity Summaries 2026, Titanium (USGS, February 2026) | report | 2026 | 1 value | |
| Safety data sheet, Nitinol Alloys (Resonetics, 29 CFR 1910.1200 format, 2026) | datasheet | 2026 | 3 values | |
| Ion release and surface characterization of nanostructured nitinol during long-term testing | paper | 2019 | 3 values | |
| Spray forming of NiTi and NiTiPd shape-memory alloys (NASA Glenn, NTRS 20080047469) | paper | 2008 | 1 value |