Alumel KN
Nickel-base alloy, nominal 95 % Ni with 2 % Al, 2 % Mn and 1 % Si by weight (Wikipedia and Advent Research Materials)
Also known as UNS N02016, ASTM E-230, Alumel
Alumel is a magnetic nickel alloy of about 95 % nickel with 2 % aluminium, 2 % manganese and 1 % silicon.
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.
Stay solid when hot
1399 °C melting point
Stay light
8.60 g/cm3
Strength in hard wire
1170 MPa tensile
Recipe, share of the weight
- Ni 95%Nickel
- Mn 2%Manganese
- Al 2%Aluminium
- Si 1%Silicon
Best for
Negative leg of a base-metal thermocouple used in oxidising or neutral air, where the Chromel/Alumel pair is printed to 1260 °C, with a melting point of 1399 °C and a resistivity of 29.4 µΩ·cm at 20 °C
Weakest at
Low-oxygen and sulphur exposure of the Type K pair: Pyromation reports green rot in the chromel leg and large negative drift between 816 and 1038 °C, and failure on sulphur exposure
Risk at a glance
- People Low. No alloy-specific classification
- If it fails High. Failure on sulphur exposure
- Corrosion Severe. Pyromation says Type K is subject to failure if exposed to sulphur.
Quick facts: KN
| Property | Value | Basis |
|---|---|---|
| Density | 8.6 to 8.61 g/cm³ | 2 sourced values across conditions |
| Yield strength | 276 MPa | 1 sourced value |
| Tensile strength | 586 to 1,170 MPa | 3 sourced values across conditions |
| Thermal conductivity | 29.7 W/(m·K) | 1 sourced value |
| Thermal expansion (CTE) | 12 ppm/K | 1 sourced value |
| Melting point | 1,399 °C | 1 sourced value |
| Specific heat | 523 J/(kg·K) | 1 sourced value |
| Electrical resistivity | 2.9e-7 Ω·m | 1 sourced value |
What is the density of Alumel (KN)?
Alumel (KN) has a density of 8.6 to 8.61 g/cm³. 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 thermal conductivity of Alumel (KN)?
Alumel (KN) has a thermal conductivity of 29.7 W/(m·K). The source and test conditions are listed in the properties table on this page.
What is the coefficient of thermal expansion of Alumel (KN)?
Alumel (KN) has a coefficient of thermal expansion of 12 ppm/K. The source and test conditions are listed in the properties table on this page.
What is the melting point of Alumel (KN)?
Alumel (KN) has a melting point of 1,399 °C. The source and test conditions are listed in the properties table on this page.
What is the yield strength of Alumel (KN)?
Alumel (KN) has a yield strength of 276 MPa. The source and test conditions are listed in the properties table on this page.
What are the other names and codes for Alumel (KN)?
Alumel (KN) is also written as UNS N02016, ASTM E-230, Alumel. Each code is printed in the source listed beside it in the designations table.
What is Alumel (KN) used for?
Uses recorded in the sources include Type K (chromel-alumel) thermocouple sensor; Sheathed micro-miniature Type K thermocouple probe for thermal protection system measurement.
Why it exists
Alumel is the negative leg of the Type K thermocouple. It is a nickel alloy with small additions of aluminium, manganese and silicon, and it resists oxidation well enough that bare wire can be used in air. Its melting point is 1399 °C and its density is 8.60 g/cm3 in the Concept Alloys datasheet. The pair's weak points are the chromel leg, which causes green rot and drift, and sulphur, which the pair does not tolerate.
Where it's used
Type K thermocouples
Pyromation says Type K is mostly used above 538 °C and is recommended for continuous oxidizing or neutral atmospheres. Alumel is the negative leg.
Thermal protection probes
NASA Ames describes a sheathed micro-miniature Type K probe, the SMART instrument, for thermal protection system materials in ground testing and flight. A Type K probe was tried in a furnace to 800 °C and agreed with the reference to within 10 °C.
Recipe
Nickel-base alloy, nominal 95 % Ni with 2 % Al, 2 % Mn and 1 % Si by weight (Wikipedia and Advent Research Materials); the Concept Alloys sheet gives 2 % Si and 1 % Al instead
Alumel is a nickel alloy of about 95 % nickel with aluminium, manganese and silicon (Wikipedia and Advent Research Materials). The Concept Alloys datasheet gives the same nickel and manganese but swaps aluminium and silicon, so the split of the two minor elements is uncertain.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Nickel Ni | 95% | The matrix of the alloy. |
| Manganese Mn | 2% | Minor addition, 2 % in the Wikipedia, Advent and Concept Alloys sources. |
| Aluminium Al | 2% | Minor addition, 2 % in Wikipedia and Advent, 1 % in the Concept Alloys sheet. |
| Silicon Si | 1% | Minor addition, 1 % in Wikipedia and Advent, 2 % in the Concept Alloys sheet. |
Weight shares are as printed in the sources.
What it can do
Stay solid when hot
1399 °C melting point
measured
The melting point is 1399 °C, as printed in the Concept Alloys datasheet.
Stay light
8.60 g/cm3
measured
Density is 8.60 g/cm3 in the Concept Alloys datasheet, and 8.61 g/cm3 in Wikipedia.
Strength in hard wire
1170 MPa tensile
measured
Wikipedia prints 1170 MPa tensile strength for the hard temper and 1030 MPa for the stress-relieved temper.
How it compares
This profile has no second thermocouple alloy read in the same run, so the compare rows use alumel's own figures: density, melting point and electrical resistivity. Read them as alumel's values, not as a ranking against chromel or another metal.
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. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.
| Measurement | KN | NiCr 80/20 | Ni-10Cr (Chromel-P) | Ni-Cr-Al-Cu precision resistance alloy |
|---|---|---|---|---|
| Thermal behavior and safety | ||||
| Approximate melting point, Alumel | 1399 °C3 | 1400 °C | 1430 °C | 1350 °C |
| Thermal conductivity at 100 °C, Alumel | 0.297 W/(cm·°C)7 | 15 W/(m·K) | 19.2 W/(m·K) | 14.6 W/(m·K) |
| Specific heat capacity, Alumel | 0.523 J/(g·K)8 | 0.46 kJ/(kg·K) | 0.448 kJ/(kg·K) | 435 J/(kg·K) |
| Physical and electrical | ||||
| Density, Alumel (vendor datasheet) | 8.6 g/cm³1 | 8.3 g/cm³ | 8.72 g/cm³ | 8.1 g/cm³ |
| Density, Alumel (Wikipedia) | 8.61 g/cm³2 | 8.3 g/cm³ | 8.72 g/cm³ | 8.1 g/cm³ |
| Electrical resistivity at 20 °C, Alumel | 29.4 µΩ·cm4 | 1.09 Ω mm2/m | 0.706 Ω mm2/m | 133 µΩ·cm |
| Temperature behavior | ||||
| Temperature coefficient of resistance, AlumelValue printed in a manufacturer datasheet | 18.8 10-4 /°C5 | no data | no data | 10 ppm/°C |
| Curie point, Alumel | 152 °C14 | no data | no data | no data |
| Other measurements | ||||
| Coefficient of thermal expansion, 20 to 100 °C, AlumelValue printed in a manufacturer datasheet | 12 ppm/K6 | 14.1 ppm/K | 17 ppm/K | 13 ppm/K |
| Yield strength, annealed, Alumel | 40 ksi9 | 420 MPa | 45 ksi | > 300 MPa |
| Tensile strength, annealed, Alumel | 85 ksi10 | 810 MPa | 95 ksi | 650 to 900 MPa |
| Tensile strength, hard temper, Alumel | 1170 MPa11 | 810 MPa | 95 ksi | 650 to 900 MPa |
| Tensile strength, stress-relieved, Alumel | 1030 MPa12 | 810 MPa | 95 ksi | 650 to 900 MPa |
| Elongation, annealed, Alumel | 35 %13 | 30 % | 35 % | > 30 % |
Why choose it, and why not
Good for
- Negative leg of a Type K thermocouple: a nickel alloy with a 1399 °C melting point (Concept Alloys).
- Oxidising or neutral air: bare wire, with a printed range of -200 to +1260 °C for the pair (Concept Alloys).
- Annealed wire: 85 ksi tensile strength and 35 % elongation (Concept Alloys).
Watch out for
- Low-oxygen drift: large negative calibration drift between 816 and 1038 °C in the Type K pair (Pyromation).
- Sulphur: Type K is subject to failure if exposed to sulphur (Pyromation).
- Composition: Wikipedia and Concept Alloys disagree on whether aluminium or silicon is 2 %.
- No corrosion rate, outgassing or radiation data for alumel alone were found.
Alumel is the standard negative leg of a base-metal thermocouple. It is a nickel alloy with a 1399 °C melting point, and the pair is rated to 1260 °C in air. Its limits are in the chromel leg and in sulphur exposure, and the profile has no alumel-only corrosion rate, drift value or radiation data.
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 |
|---|---|
| UNS | N02016 |
| ASTM | E-230 (thermocouple specification, printed as ASTM E-230) |
| Trade name | Alumel (registered trademark of Concept Alloys, Inc.) |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Density, Alumel (vendor datasheet) | Typical value printed in the Concept Alloys technical data sheet | grade Alumel, nominal 95 Nitemperature not stated | — |
| 2 | Density, Alumel (Wikipedia) | Value printed in the properties table of a secondary compilation | grade Alumel, 95 Ni 2 Mn 2 Al 1 Sitemperature not stated | Wikipedia is a secondary compilation. Concept Alloys prints 8.60 g/cm3, and another supplier prints 8.58 g/cm3, which is not stored. The vendor datasheet value is the one used in the summary. |
| 3 | Approximate melting point, Alumel | Value printed in a manufacturer datasheet, given there as 2550 °F and 1399 °C | grade Alumel, nominal 95 Nipressure not stated | — |
| 4 | Electrical resistivity at 20 °C, Alumel | Nominal value printed in a manufacturer datasheet; the datasheet labels the unit µΩ/cm3, and the number is read as µΩ·cm (Wikipedia gives 0.294 µΩ·m, the same magnitude) | grade Alumel, nominal 95 Nitemperature 20 °Cunit in source µΩ/cm3 | — |
| 5 | Temperature coefficient of resistance, Alumel | — | grade Alumel, nominal 95 Nitemperature 20 to 100 °Cunit in source Ω/Ω/°C E-4 | Non-canonical property name; temperature_coefficient_of_resistance is not in the canonical property file. |
| 6 | Coefficient of thermal expansion, 20 to 100 °C, Alumel | — | grade Alumel, nominal 95 Nitemperature 20 to 100 °Cunit in source cm/cm/°C E-6 | — |
| 7 | Thermal conductivity at 100 °C, Alumel | Value printed in a manufacturer datasheet; the printed unit is kept in conditions and is the same as 29.7 W/(m·K) | grade Alumel, nominal 95 Nitemperature 100 °Cunit in source W/cm2/cm/°C | Wikipedia prints 29.7 W/(m·K) without a temperature, which is the same figure in SI units. |
| 8 | Specific heat capacity, Alumel | Value printed in the properties table of a secondary compilation | grade Alumel, 95 Ni 2 Mn 2 Al 1 Sitemperature not statedunit in source J g-1 K-1 | — |
| 9 | Yield strength, annealed, Alumel | Typical value printed in a manufacturer datasheet | grade Alumel, nominal 95 Nitemper annealedtemperature not stated | — |
| 10 | Tensile strength, annealed, Alumel | Typical value printed in a manufacturer datasheet | grade Alumel, nominal 95 Nitemper annealedtemperature not stated | — |
| 11 | Tensile strength, hard temper, Alumel | Value printed in the properties table of a secondary compilation | grade Alumeltemper hardtemperature not stated | — |
| 12 | Tensile strength, stress-relieved, Alumel | Value printed in the properties table of a secondary compilation | grade Alumeltemper stress relievedtemperature not stated | — |
| 13 | Elongation, annealed, Alumel | Typical value printed in a manufacturer datasheet | grade Alumel, nominal 95 Nitemper annealedtemperature not stated | — |
| 14 | Curie point, Alumel | Value printed in the properties table of a secondary compilation, which cites a 1977 paper that was not read in this run | grade Alumel, 95 Ni 2 Mn 2 Al 1 Si | Non-canonical property name; curie_temperature is in the canonical file. The source does not state a test method here, and another paper seen only in a search result gives a higher figure, so this value is not verified. |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Oxidising or neutral air, bare wire | low | The datasheet says the alloy resists oxidation well enough for bare wire to be used across the working range.1 |
| Low-oxygen atmosphere, 816 to 1038 °C | moderate | Green rot and large negative drift come from chromium in the chromel leg, not the alumel leg.2 |
| Sulphur-bearing atmosphere | severe | Pyromation says Type K is subject to failure if exposed to sulphur.3 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Oxidising or neutral air, bare wire | Concept Alloys says the superior resistance of the alloys to oxidation allows bare metals to be used throughout the useful range, from -200 °C to 1260 °C for the pair. Pyromation says Type K is recommended for continuous oxidizing or neutral atmospheres. Neither source gives an oxide growth rate, weight gain or test duration for alumel alone. | environment air, oxidising or neutralbasis vendor statements; no test duration stated |
| 2 | Low-oxygen atmosphere, 816 to 1038 °C | Pyromation says chromium in the positive leg is oxidized preferentially at certain low oxygen concentrations, causing green rot and large negative calibration drift, most serious between 816 and 1038 °C. The mechanism is in the positive leg. No alumel-specific drift or oxidation value was found. | environment low oxygen concentration, Type K pairbasis vendor statement; no test duration stated |
| 3 | Sulphur-bearing atmosphere | The statement covers the Type K pair, not alumel alone. The source gives no exposure time, concentration or rate. | environment sulphurbasis vendor statement for the Type K pair |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
Alumel is about 95 % nickel. The sources give no alloy-specific hazard classification, so the raw materials and the nickel-wire SDS are the better guide.
- Supplier classification
- The Airgas nickel wire and rod SDS is classified as Not Classified under GHS and has no signal word. It covers a nickel wire and rod product, not alumel itself.
- Fume
- The same SDS lists manganese (as fume) and nickel among its ingredients, so grinding or welding alumel can produce fume with those metals.
If it fails
The failure routes in the sources are temperature, low-oxygen exposure and sulphur. The sources give limits but no failure rates for alumel alone.
- Green rot and drift
- Pyromation says chromium in the chromel leg is oxidized preferentially at low oxygen between 816 and 1038 °C, causing large negative drift. The alumel leg is not the cause in the source.
- Sulphur
- Pyromation says Type K is subject to failure if exposed to sulphur.
- Overheating
- The pair's printed range tops out at 1260 °C (Concept Alloys). Above it the sources give no time to failure.
Handling and storage
- Keep it below the limit
- Keep the pair within its printed range of -200 to +1260 °C (Concept Alloys).
- Protect the tube
- Ventilate or inert-seal the protection tube, as Pyromation recommends.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Negative calibration drift in low-oxygen airmoderate severity | Low oxygen concentration between 816 and 1038 °C in the Type K pairLarge negative calibration drift, which Pyromation attributes to preferential oxidation of chromium in the positive leg |
| Failure on sulphur exposurehigh severity | Exposure of the Type K pair to sulphurPyromation says the pair is subject to failure. The source gives no time or concentration. |
| Oxidation above the operating limitmoderate severity | Operation above 1260 °CThe pair's printed range tops out at 1260 °C. No oxidation rate or time to failure above it is given for alumel. |
Side effects on surrounding parts
| Affects | Effect |
|---|---|
| Handling of dust and fume from grinding or welding | Welding and grinding fume from nickel-base wire can contain nickel and manganese compounds, and the Airgas SDS says welding fumes and gases cannot be classified simply. |
Handling and storage
- Keep the Chromel/Alumel pair within its printed range of -200 to +1260 °C; the range is for the pair, not for alumel alone (Concept Alloys).
- Ventilate or inert-seal the protection tube to limit green rot and drift, as Pyromation recommends.
Supply and geography
How common the raw materials are and where they come from.
Nickel
- Top producers (2025)
- Indonesia 66.7%, Philippines 6.9%, Russia 5.1%, Canada 3.6%
- Recycling
- USGS: most secondary nickel is the nickel content of stainless-steel scrap, and nickel in alloyed form is recovered from processing nickel-containing waste.
- Substitutes
- USGS: low-nickel, duplex or ultrahigh-chromium stainless steels can replace austenitic grades; titanium alloys can substitute for nickel-base alloys in corrosive environments.
Manganese
- Top producers (2025)
- South Africa 38%, Gabon 25%, Ghana 10%, Australia 8%
- Recycling
- USGS: manganese was recycled incidentally as a constituent of ferrous and nonferrous scrap; scrap recovery specifically for manganese was negligible.
Aluminium
- Top producers (2025)
- China 60.8%, India 5.7%, Russia 5.3%, Canada 4.5%
- Recycling
- USGS: aluminum recovered from purchased scrap in the United States was about 3.6 million tons in 2025.
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: alumel
spore_version: 0.2
family: resistance-and-thermocouple-alloys
name: Alumel
abbreviation: KN
role: negative leg of the Type K thermocouple
category: metals
type: nickel-superalloys
summary: |
Alumel is a magnetic nickel alloy of about 95 % nickel with 2 % aluminium, 2 % manganese and 1 % silicon. It is the negative leg of the Type K (chromel-alumel) thermocouple. Concept Alloys gives its approximate melting point as 1399 °C and its specific gravity as 8.60, and gives an annealed tensile strength of 85 ksi. Its datasheet says the alloy resists oxidation well enough for bare wire to be used across the pair's working range. The pair itself is not free of trouble: Pyromation reports green rot and large negative drift in low-oxygen air between 816 and 1038 °C, and says Type K fails if exposed to sulphur.
best_for: Negative leg of a base-metal thermocouple used in oxidising or neutral air, where the Chromel/Alumel pair is printed to 1260 °C, with a melting point of 1399 °C and a resistivity of 29.4 µΩ·cm at 20 °C
weakest_at: 'Low-oxygen and sulphur exposure of the Type K pair: Pyromation reports green rot in the chromel leg and large negative drift between 816 and 1038 °C, and failure on sulphur exposure'
identity:
formula: Nickel-base alloy, nominal 95 % Ni with 2 % Al, 2 % Mn and 1 % Si by weight (Wikipedia and Advent Research Materials); the Concept Alloys sheet gives 2 % Si and 1 % Al instead
source: advent-alumel
where: 'Product description section, composition sentence: approximately 95 % nickel, 2 % aluminum, 2 % manganese and 1 % silicon'
designations:
- system: UNS
code: N02016
source: concept-datasheet-alumel
where: Industry Specifications line, UNS N02016
- system: ASTM
code: E-230
note: thermocouple specification, printed as ASTM E-230
source: concept-datasheet-alumel
where: Industry Specifications line
- system: Trade name
code: Alumel
note: registered trademark of Concept Alloys, Inc.
source: wikipedia-alumel
where: Lead section, trademark sentence
tags:
environments: []
stresses:
- extreme-heat
applications:
- thermal-control
- heat-shields
properties:
- benchmark: density
label: Density, Alumel (vendor datasheet)
value: 8.6
unit: g/cm3
scope: material
conditions:
grade: Alumel, nominal 95 Ni
temperature: not stated
method: Typical value printed in the Concept Alloys technical data sheet
status: ground
source: concept-datasheet-alumel
where: Typical Physical Property Data, Specific Gravity 8.60 and Density (g/cm3) 8.60
- benchmark: density
label: Density, Alumel (Wikipedia)
value: 8.61
unit: g/cm3
scope: material
conditions:
grade: Alumel, 95 Ni 2 Mn 2 Al 1 Si
temperature: not stated
method: Value printed in the properties table of a secondary compilation
status: ground
note: Wikipedia is a secondary compilation. Concept Alloys prints 8.60 g/cm3, and another supplier prints 8.58 g/cm3, which is not stored. The vendor datasheet value is the one used in the summary.
source: wikipedia-alumel
where: Properties table, Density
- benchmark: melting_point
label: Approximate melting point, Alumel
value: 1399
unit: °C
scope: material
conditions:
grade: Alumel, nominal 95 Ni
pressure: not stated
method: Value printed in a manufacturer datasheet, given there as 2550 °F and 1399 °C
status: ground
source: concept-datasheet-alumel
where: Typical Physical Property Data, Approximate Melting Point 2550°F (1399°C)
- benchmark: electrical_resistivity
label: Electrical resistivity at 20 °C, Alumel
value: 29.4
unit: µΩ·cm
scope: material
conditions:
grade: Alumel, nominal 95 Ni
temperature: 20 °C
unit_in_source: µΩ/cm3
method: Nominal value printed in a manufacturer datasheet; the datasheet labels the unit µΩ/cm3, and the number is read as µΩ·cm (Wikipedia gives 0.294 µΩ·m, the same magnitude)
status: ground
source: concept-datasheet-alumel
where: Typical Physical Property Data, Nominal Resistivity (µΩ/cm3) 29.4 at 20 °C
- benchmark: temperature_coefficient_of_resistance
label: Temperature coefficient of resistance, Alumel
value: 18.8
unit: 10-4 /°C
scope: material
conditions:
grade: Alumel, nominal 95 Ni
temperature: 20 to 100 °C
unit_in_source: Ω/Ω/°C E-4
method: Value printed in a manufacturer datasheet
status: ground
note: Non-canonical property name; temperature_coefficient_of_resistance is not in the canonical property file.
source: concept-datasheet-alumel
where: Typical Physical Property Data, Temp. Coef. Of Resistance (Ω/Ω/°C) E-4 18.8 (20 to 100 °C)
- benchmark: cte
label: Coefficient of thermal expansion, 20 to 100 °C, Alumel
value: 12
unit: ppm/K
scope: material
conditions:
grade: Alumel, nominal 95 Ni
temperature: 20 to 100 °C
unit_in_source: cm/cm/°C E-6
method: Value printed in a manufacturer datasheet
status: ground
source: concept-datasheet-alumel
where: Typical Physical Property Data, Temp. Coef. Of Expansion (cm/cm/°C) E-6 12.0 (20 to 100 °C)
- benchmark: thermal_conductivity
label: Thermal conductivity at 100 °C, Alumel
value: 0.297
unit: W/(cm·°C)
scope: material
conditions:
grade: Alumel, nominal 95 Ni
temperature: 100 °C
unit_in_source: W/cm2/cm/°C
method: Value printed in a manufacturer datasheet; the printed unit is kept in conditions and is the same as 29.7 W/(m·K)
status: ground
note: Wikipedia prints 29.7 W/(m·K) without a temperature, which is the same figure in SI units.
source: concept-datasheet-alumel
where: Typical Physical Property Data, Thermal Cond. (W/cm2/cm/°C) 0.297 (at 100 °C)
- benchmark: specific_heat
label: Specific heat capacity, Alumel
value: 0.523
unit: J/(g·K)
scope: material
conditions:
grade: Alumel, 95 Ni 2 Mn 2 Al 1 Si
temperature: not stated
unit_in_source: J g-1 K-1
method: Value printed in the properties table of a secondary compilation
status: ground
source: wikipedia-alumel
where: Properties table, Specific heat
- benchmark: yield_strength
label: Yield strength, annealed, Alumel
value: 40
unit: ksi
scope: material
conditions:
grade: Alumel, nominal 95 Ni
temper: annealed
temperature: not stated
method: Typical value printed in a manufacturer datasheet
status: ground
source: concept-datasheet-alumel
where: Typical Mechanical Properties, Yield Strength, annealed (ksi) 40
- benchmark: ultimate_tensile_strength
label: Tensile strength, annealed, Alumel
value: 85
unit: ksi
scope: material
conditions:
grade: Alumel, nominal 95 Ni
temper: annealed
temperature: not stated
method: Typical value printed in a manufacturer datasheet
status: ground
source: concept-datasheet-alumel
where: Typical Mechanical Properties, Tensile Strength, annealed (ksi) 85
- benchmark: ultimate_tensile_strength
label: Tensile strength, hard temper, Alumel
value: 1170
unit: MPa
scope: material
conditions:
grade: Alumel
temper: hard
temperature: not stated
method: Value printed in the properties table of a secondary compilation
status: ground
source: wikipedia-alumel
where: Properties table, Tensile strength (hard) 1170 MPa
- benchmark: ultimate_tensile_strength
label: Tensile strength, stress-relieved, Alumel
value: 1030
unit: MPa
scope: material
conditions:
grade: Alumel
temper: stress relieved
temperature: not stated
method: Value printed in the properties table of a secondary compilation
status: ground
source: wikipedia-alumel
where: Properties table, Tensile strength (stress relieved) 1030 MPa
- benchmark: elongation
label: Elongation, annealed, Alumel
value: 35
unit: '%'
scope: material
conditions:
grade: Alumel, nominal 95 Ni
temper: annealed
temperature: not stated
method: Typical value printed in a manufacturer datasheet
status: ground
source: concept-datasheet-alumel
where: Typical Mechanical Properties, Elongation, annealed (%) 35
- benchmark: curie_temperature
label: Curie point, Alumel
value: 152
unit: °C
scope: material
conditions:
grade: Alumel, 95 Ni 2 Mn 2 Al 1 Si
method: Value printed in the properties table of a secondary compilation, which cites a 1977 paper that was not read in this run
status: ground
note: Non-canonical property name; curie_temperature is in the canonical file. The source does not state a test method here, and another paper seen only in a search result gives a higher figure, so this value is not verified.
source: wikipedia-alumel
where: Properties table, Curie point 152 °C
corrosion:
- environment: Oxidising or neutral air, bare wire
headline: The datasheet says the alloy resists oxidation well enough for bare wire to be used across the working range.
effect: Concept Alloys says the superior resistance of the alloys to oxidation allows bare metals to be used throughout the useful range, from -200 °C to 1260 °C for the pair. Pyromation says Type K is recommended for continuous oxidizing or neutral atmospheres. Neither source gives an oxide growth rate, weight gain or test duration for alumel alone.
rating: low
conditions:
environment: air, oxidising or neutral
basis: vendor statements; no test duration stated
source: concept-datasheet-alumel
where: Overview paragraph, superior resistance of the alloys to oxidation
- environment: Low-oxygen atmosphere, 816 to 1038 °C
headline: Green rot and large negative drift come from chromium in the chromel leg, not the alumel leg.
effect: Pyromation says chromium in the positive leg is oxidized preferentially at certain low oxygen concentrations, causing green rot and large negative calibration drift, most serious between 816 and 1038 °C. The mechanism is in the positive leg. No alumel-specific drift or oxidation value was found.
rating: moderate
conditions:
environment: low oxygen concentration, Type K pair
basis: vendor statement; no test duration stated
source: pyromation-types
where: Type K Thermocouple section, green rot and drift window sentences
- environment: Sulphur-bearing atmosphere
headline: Pyromation says Type K is subject to failure if exposed to sulphur.
effect: The statement covers the Type K pair, not alumel alone. The source gives no exposure time, concentration or rate.
rating: severe
conditions:
environment: sulphur
basis: vendor statement for the Type K pair
source: pyromation-types
where: Type K Thermocouple section, Sulphur sentence
risks:
hazards:
- text: 'Airgas nickel wire and rod SDS: GHS Hazard Classification is Not Classified, with no symbol or signal word. This sheet covers a nickel wire and rod product, not Alumel itself.'
ghs: []
source: airgas-nickel-sds
where: Section 2, GHS Hazard Classification line
- text: The same SDS lists manganese (as fume), nickel and silicon among its ingredients and gives exposure limits for them.
ghs: []
source: airgas-nickel-sds
where: Ingredient table (Manganese limits as fume, Nickel, Silicon) and the exposure limits table
failure_risks:
- mode: Negative calibration drift in low-oxygen air
trigger: Low oxygen concentration between 816 and 1038 °C in the Type K pair
consequence: Large negative calibration drift, which Pyromation attributes to preferential oxidation of chromium in the positive leg
severity: moderate
source: pyromation-types
where: Type K Thermocouple section, drift window sentence
- mode: Failure on sulphur exposure
trigger: Exposure of the Type K pair to sulphur
consequence: Pyromation says the pair is subject to failure. The source gives no time or concentration.
severity: high
source: pyromation-types
where: Type K Thermocouple section, Sulphur sentence
- mode: Oxidation above the operating limit
trigger: Operation above 1260 °C
consequence: The pair's printed range tops out at 1260 °C. No oxidation rate or time to failure above it is given for alumel.
severity: moderate
source: concept-datasheet-alumel
where: Overview paragraph, temperature range
side_effects:
- text: Welding and grinding fume from nickel-base wire can contain nickel and manganese compounds, and the Airgas SDS says welding fumes and gases cannot be classified simply.
affects: Handling of dust and fume from grinding or welding
source: airgas-nickel-sds
where: Section 2, Hazards line on welding fumes and gases
handling:
- text: Keep the Chromel/Alumel pair within its printed range of -200 to +1260 °C; the range is for the pair, not for alumel alone (Concept Alloys).
source: concept-datasheet-alumel
where: Overview paragraph, temperature range
- text: Ventilate or inert-seal the protection tube to limit green rot and drift, as Pyromation recommends.
source: pyromation-types
where: Type K Thermocouple section, Prevention sentence
mitigations: []
uses:
- application: thermal-control
device: Type K (chromel-alumel) thermocouple sensor
example: Pyromation says Type K is mostly used above 538 °C and is recommended for continuous oxidizing or neutral atmospheres.
source: pyromation-types
where: Type K Thermocouple section, Typical usage and Recommended atmospheres
- application: heat-shields
device: Sheathed micro-miniature Type K thermocouple probe for thermal protection system measurement
example: NASA Ames describes the Sheathed Miniature Aerothermal Reentry Thermocouple as available for thermal protection system materials for ground testing and flight. A Type K probe was tried in a furnace dry run to 800 °C, and its reading agreed with the reference to within 10 °C, but the probe stopped working in a cooling cycle after dwell at 800 °C.
source: nasa-smart-2016
where: Abstract; verification section, Type K MMTCP trial paragraph
supply:
- subject: Nickel
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: Canada
share_percent: 3.6
year: 2025
recycling: 'USGS: most secondary nickel is the nickel content of stainless-steel scrap, and nickel in alloyed form is recovered from processing nickel-containing waste.'
substitutes:
- 'USGS: low-nickel, duplex or ultrahigh-chromium stainless steels can replace austenitic grades; titanium alloys can substitute for nickel-base alloys in corrosive environments.'
source: usgs-mcs2026-nickel
where: World Mine Production and Reserves table, 2025e column (world total 3,900,000 t; shares calculated by Space Mushroom against that printed total); Recycling; Substitutes
- subject: Manganese
producers:
- country: South Africa
share_percent: 38
year: 2025
- country: Gabon
share_percent: 25
year: 2025
- country: Ghana
share_percent: 10
year: 2025
- country: Australia
share_percent: 8
year: 2025
recycling: 'USGS: manganese was recycled incidentally as a constituent of ferrous and nonferrous scrap; scrap recovery specifically for manganese was negligible.'
source: usgs-mcs2026-manganese
where: World Mine Production table, 2025e column (world total 20,000 thousand, rounded; shares calculated by Space Mushroom against that printed total); Recycling; World Resources paragraph (South Africa about 70 % of resources)
- subject: Aluminium
producers:
- country: China
share_percent: 60.8
year: 2025
- country: India
share_percent: 5.7
year: 2025
- country: Russia
share_percent: 5.3
year: 2025
- country: Canada
share_percent: 4.5
year: 2025
recycling: 'USGS: aluminum recovered from purchased scrap in the United States was about 3.6 million tons in 2025.'
source: usgs-mcs2026-aluminum
where: World Smelter Production and Capacity table, 2025e column (world total 74,000 thousand, rounded; shares calculated by Space Mushroom against that printed total); Recycling paragraph
documents:
- title: 'Concept Alloys: Alumel technical data sheet (Rev. 12-23-09)'
type: datasheet
url: https://conceptalloys.com/wp-content/uploads/2013/10/AlumelGMVdatasheet091223.pdf
year: 2009
- title: 'Wikipedia: Alumel'
type: database
url: https://en.wikipedia.org/wiki/Alumel
- title: 'Advent Research Materials: Alumel product page'
type: datasheet
url: https://www.advent-rm.com/materials/alumel
- title: 'Pyromation: Thermocouple types'
type: datasheet
url: https://www.pyromation.com/products/Thermocouple/Thermocouple-Types.aspx
- title: 'NASA Ames: Development of a Sheathed Miniature Aerothermal Reentry Thermocouple for Thermal Protection System Materials (AIAA paper)'
type: report
url: https://ntrs.nasa.gov/api/citations/20160000315/downloads/20160000315.pdf
year: 2016
- 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: Manganese'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-manganese.pdf
year: 2026
- title: 'USGS Mineral Commodity Summaries 2026: Aluminum'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
year: 2026
- title: 'Airgas: Nickel Wire and Rod safety data sheet (approval 2-1-2016)'
type: sds
url: https://www.airgas.com/msds/005727.pdf
year: 2016
gaps:
- 'Curie temperature: Wikipedia prints 152 °C and cites a 1977 paper that was not read in this run. Another paper seen only in a search result gives about 464 K. The value is kept with a note and is not verified.'
- 'Composition conflict: Wikipedia and Advent Research Materials give 2 % Al and 1 % Si; the Concept Alloys sheet gives 2 % Si and 1 % Al, and its product page gives the same split. The profile uses the majority split. Check the vendor certificate before design use.'
- 'Density: Concept Alloys gives 8.60 g/cm3 and Wikipedia 8.61; another supplier prints 8.58 g/cm3, which is not stored.'
- No corrosion rate, oxidation weight gain, mass loss or drift rate for alumel alone was found. The green rot and drift data concern the Type K pair, mainly the chromel leg.
- No hardness value for alumel was found, and no outgassing, atomic-oxygen or radiation data were found.
- The Type K pair range of -200 to +1260 °C is a pair value, not an alumel-only property, so it is not stored as an alumel property. No alumel-only maximum service temperature was found.
- 'Tensile values: the datasheet gives annealed values only. The hard and stress-relieved temper figures come from Wikipedia, a secondary compilation, and no primary source was found for them.'
- No alumel-specific safety data sheet was found. The Airgas SDS covers a nickel wire and rod product.
- 'Critical-mineral list status for nickel, manganese and aluminium: the USGS 2026 summaries read in this run do not name a critical-minerals list in the extracted text, so no list entry is recorded.'
- 'Silicon supply: no USGS or other silicon supply source was read in this run, so silicon is left out of the supply list.'
- The ANSI letter designation KN printed on the Concept Alloys sheet has no matching system in the designation schema, so it is not listed.
- Extension-wire grades (Concept Alloys extension grade datasheet) and the Type K pair are not profiled here.
sources:
wikipedia-alumel:
title: Alumel (Wikipedia)
url: https://en.wikipedia.org/wiki/Alumel
kind: web
license: CC BY-SA 4.0 (cited, not reproduced)
concept-datasheet-alumel:
title: Alumel technical data sheet (Concept Alloys, Inc., Rev. 12-23-09)
url: https://conceptalloys.com/wp-content/uploads/2013/10/AlumelGMVdatasheet091223.pdf
year: 2009
kind: datasheet
license: Manufacturer datasheet (cited, not reproduced)
advent-alumel:
title: Alumel product page (Advent Research Materials)
url: https://www.advent-rm.com/materials/alumel
kind: web
license: Supplier web page (cited, not reproduced)
pyromation-types:
title: Thermocouple types (Pyromation)
url: https://www.pyromation.com/products/Thermocouple/Thermocouple-Types.aspx
kind: web
license: Supplier web page (cited, not reproduced)
nasa-smart-2016:
title: Development of a Sheathed Miniature Aerothermal Reentry Thermocouple for Thermal Protection System Materials (NASA Ames Research Center)
url: https://ntrs.nasa.gov/api/citations/20160000315/downloads/20160000315.pdf
year: 2016
kind: report
license: NASA technical report (public)
usgs-mcs2026-nickel:
title: Mineral Commodity Summaries 2026, Nickel
id: USGS MCS 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-mcs2026-manganese:
title: Mineral Commodity Summaries 2026, Manganese
id: USGS MCS 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-manganese.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-mcs2026-aluminum:
title: Mineral Commodity Summaries 2026, Aluminum
id: USGS MCS 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
year: 2026
kind: report
license: public domain (USGS)
airgas-nickel-sds:
title: Safety Data Sheet, Nickel Wire and Rod (Airgas)
url: https://www.airgas.com/msds/005727.pdf
year: 2016
kind: datasheet
license: Supplier safety data sheet (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-10-26'
review:
status: draft
method: assistant
checked_values: 14
unreachable: 3
caveats: 4
note: 'Values were read by an AI assistant on 2026-10-26 from the pages named in each entry. Concept Alloys values are from its Alumel technical data sheet. Wikipedia values are a secondary compilation and are marked as such. Unreachable in this run: the Cambridge University Type K drift page (HTTP 403), the NIST ITS-90 table (not fetched) and a California Fine Wire product page (behind a bot challenge, so its values were dropped). Caveats: the composition split between aluminium and silicon conflicts between sources; the Curie point is not verified against the original paper; the Type K pair range is a pair value and is not stored as an alumel property; supply shares are calculated from printed world totals.'
story:
risk_groups:
- title: For people
lead: Alumel is about 95 % nickel. The sources give no alloy-specific hazard classification, so the raw materials and the nickel-wire SDS are the better guide.
level: 1
verdict: No alloy-specific classification
points:
- label: Supplier classification
line: The Airgas nickel wire and rod SDS is classified as Not Classified under GHS and has no signal word. It covers a nickel wire and rod product, not alumel itself.
- label: Fume
line: The same SDS lists manganese (as fume) and nickel among its ingredients, so grinding or welding alumel can produce fume with those metals.
- title: If it fails
lead: The failure routes in the sources are temperature, low-oxygen exposure and sulphur. The sources give limits but no failure rates for alumel alone.
points:
- label: Green rot and drift
line: Pyromation says chromium in the chromel leg is oxidized preferentially at low oxygen between 816 and 1038 °C, causing large negative drift. The alumel leg is not the cause in the source.
- label: Sulphur
line: Pyromation says Type K is subject to failure if exposed to sulphur.
- label: Overheating
line: The pair's printed range tops out at 1260 °C (Concept Alloys). Above it the sources give no time to failure.
- title: Handling and storage
points:
- label: Keep it below the limit
line: Keep the pair within its printed range of -200 to +1260 °C (Concept Alloys).
- label: Protect the tube
line: Ventilate or inert-seal the protection tube, as Pyromation recommends.
why: Alumel is the negative leg of the Type K thermocouple. It is a nickel alloy with small additions of aluminium, manganese and silicon, and it resists oxidation well enough that bare wire can be used in air. Its melting point is 1399 °C and its density is 8.60 g/cm3 in the Concept Alloys datasheet. The pair's weak points are the chromel leg, which causes green rot and drift, and sulphur, which the pair does not tolerate.
uses:
- where: Type K thermocouples
line: Pyromation says Type K is mostly used above 538 °C and is recommended for continuous oxidizing or neutral atmospheres. Alumel is the negative leg.
- where: Thermal protection probes
line: NASA Ames describes a sheathed micro-miniature Type K probe, the SMART instrument, for thermal protection system materials in ground testing and flight. A Type K probe was tried in a furnace to 800 °C and agreed with the reference to within 10 °C.
can_do:
- label: Stay solid when hot
value: 1399 °C melting point
benchmark: melting_point
line: The melting point is 1399 °C, as printed in the Concept Alloys datasheet.
- label: Stay light
value: 8.60 g/cm3
benchmark: density
line: Density is 8.60 g/cm3 in the Concept Alloys datasheet, and 8.61 g/cm3 in Wikipedia.
- label: Strength in hard wire
value: 1170 MPa tensile
benchmark: ultimate_tensile_strength
line: Wikipedia prints 1170 MPa tensile strength for the hard temper and 1030 MPa for the stress-relieved temper.
compare: 'This profile has no second thermocouple alloy read in the same run, so the compare rows use alumel''s own figures: density, melting point and electrical resistivity. Read them as alumel''s values, not as a ranking against chromel or another metal.'
compare_rows:
- label: Density
benchmark: density
- label: Melting point
benchmark: melting_point
- label: Electrical resistivity
benchmark: electrical_resistivity
handling:
- Keep continuous service at or below 1260 °C in air (California Fine Wire).
- Ventilate or inert-seal the protection tube to limit green rot and drift in the Type K pair (Pyromation).
- Treat grinding and welding fume as containing nickel and manganese compounds (Airgas SDS ingredient list).
good_for:
- 'Negative leg of a Type K thermocouple: a nickel alloy with a 1399 °C melting point (Concept Alloys).'
- 'Oxidising or neutral air: bare wire, with a printed range of -200 to +1260 °C for the pair (Concept Alloys).'
- 'Annealed wire: 85 ksi tensile strength and 35 % elongation (Concept Alloys).'
watch_out:
- 'Low-oxygen drift: large negative calibration drift between 816 and 1038 °C in the Type K pair (Pyromation).'
- 'Sulphur: Type K is subject to failure if exposed to sulphur (Pyromation).'
- 'Composition: Wikipedia and Concept Alloys disagree on whether aluminium or silicon is 2 %.'
- No corrosion rate, outgassing or radiation data for alumel alone were found.
verdict: Alumel is the standard negative leg of a base-metal thermocouple. It is a nickel alloy with a 1399 °C melting point, and the pair is rated to 1260 °C in air. Its limits are in the chromel leg and in sulphur exposure, and the profile has no alumel-only corrosion rate, drift value or radiation data.
recipe:
line: Alumel is a nickel alloy of about 95 % nickel with aluminium, manganese and silicon (Wikipedia and Advent Research Materials). The Concept Alloys datasheet gives the same nickel and manganese but swaps aluminium and silicon, so the split of the two minor elements is uncertain.
parts:
- name: Nickel
symbol: Ni
share_percent: 95
role: The matrix of the alloy.
- name: Manganese
symbol: Mn
share_percent: 2
role: Minor addition, 2 % in the Wikipedia, Advent and Concept Alloys sources.
- name: Aluminium
symbol: Al
share_percent: 2
role: Minor addition, 2 % in Wikipedia and Advent, 1 % in the Concept Alloys sheet.
- name: Silicon
symbol: Si
share_percent: 1
role: Minor addition, 1 % in Wikipedia and Advent, 2 % in the Concept Alloys sheet.
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 |
|---|---|---|---|---|
| Alumel (Wikipedia) | web | 5 values | ||
| Alumel technical data sheet (Concept Alloys, Inc., Rev. 12-23-09) | datasheet | 2009 | 12 values | |
| Alumel product page (Advent Research Materials) | web | 1 value | ||
| Thermocouple types (Pyromation) | web | 6 values | ||
| Development of a Sheathed Miniature Aerothermal Reentry Thermocouple for Thermal Protection System Materials (NASA Ames Research Center) | report | 2016 | 1 value | |
| Mineral Commodity Summaries 2026, Nickel | report | 2026 | 1 value | |
| Mineral Commodity Summaries 2026, Manganese | report | 2026 | 1 value | |
| Mineral Commodity Summaries 2026, Aluminum | report | 2026 | 1 value | |
| Safety Data Sheet, Nickel Wire and Rod (Airgas) | datasheet | 2016 | 3 values |