Nickel-manganese-gallium magnetic shape-memory alloy Ni-Mn-Ga
Ni2MnGa, stoichiometric Heusler alloy
Ni-Mn-Ga is a Heusler alloy of nickel, manganese and gallium, with stoichiometric Ni2MnGa as its reference composition.
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.
Change shape by field
5.1 to 7.3 %
Work near room temperature
201 to 342 K
Cool by magnetic entropy change
9 and 11 J/kgK
Recipe, share of the weight
- Ni 2 of 4 formula positions in stoichiometric Ni2MnGa (x = 0), then Ni2+xMn1-xGa to x = 0.19Nickel
- Mn 1 of 4 formula positions in stoichiometric Ni2MnGa (x = 0); lower in the Ni-rich seriesManganese
- Ga 1 of 4 formula positions in stoichiometric Ni2MnGa (x = 0)Gallium
Best for
Single-crystal actuators that must move by a magnetic field rather than by heating, with 5.1 to 7.3 % magnetically induced strain in the review table and a martensite that is magnetically controlled
Weakest at
Brittleness and a low martensitic transformation temperature. A 2000 MRS-J paper names both as the main obstacles to practical use, and strain is lost when the crystal is cut from the middle of the boule
Risk at a glance
- People Moderate. Nickel and gallium hazards
- If it fails High. Brittleness
- Corrosion No data. No corrosion data recorded
Why it exists
Ni-Mn-Ga is a ferromagnetic shape-memory alloy. Its martensite can be reoriented by a magnetic field, so it can change shape fast without a heating cycle. Single crystals show 5.1 to 7.3 % magnetically induced strain in one review table, and the Curie temperature of stoichiometric Ni2MnGa is about 370 K.
Where it's used
Magnetic actuators
The 2000 MRS-J paper calls Ni-Mn-Ga a good candidate for magnetic actuator materials, and the 2003 review notes that actuators and sensors based on this class of alloy need more durability first.
Magnetocaloric cooling
A 2005 conference paper reports 9 J/kgK at 338 K and 11 J/kgK at 344 K in a 26 kOe field.
Recipe
Ni2MnGa, stoichiometric Heusler alloy; the studied series is Ni2+xMn1-xGa with x from 0 to 0.19
Ni-Mn-Ga is made by argon arc melting of the three metals, followed by homogenization at 1073 K for 48 to 72 hours in argon and quenching into room-temperature water (Tsuchiya 2000). Composition is set by the Ni, Mn and Ga ratio, with stoichiometric Ni2MnGa as the reference.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Nickel Ni | 2 of 4 formula positions in stoichiometric Ni2MnGa (x = 0), then Ni2+xMn1-xGa to x = 0.19 | Sets the transition temperature and Curie temperature; excess nickel raises Tm and lowers TC |
| Manganese Mn | 1 of 4 formula positions in stoichiometric Ni2MnGa (x = 0); lower in the Ni-rich series | Carries the magnetic moment of the Heusler lattice and sets the Mn-rich compositions with the largest strain |
| Gallium Ga | 1 of 4 formula positions in stoichiometric Ni2MnGa (x = 0) | Heusler third element; its content is fixed by the Mn-Ni balance in the studied series |
Weight shares are as printed in the sources.
What it can do
Change shape by field
5.1 to 7.3 %
Single crystals of Ni48 Mn31 Ga21, Ni49.8 Mn28.5 Ga21.7 and Ni48.2 Mn30.8 Ga21 gave 5.1, 6.0 and 7.3 % magnetically induced strain.
Work near room temperature
201 to 342 K
The Curie temperature of stoichiometric Ni2MnGa is about 370 K, and the transition temperature Tm of the series runs from 201 K to 342 K.
Cool by magnetic entropy change
9 and 11 J/kgK
A magnetic entropy change of 9 J/kgK at 338 K was measured in a 26 kOe field, and 11 J/kgK at 344 K when the field was removed.
How it compares
Among the Ni2+xMn1-xGa series, the martensitic transition temperature rises with nickel content, from 201 K at x = 0 to 342 K at x = 0.19, while the Curie temperature falls toward it. Strain values come from single crystals in one review table and from a nonmodulated single crystal in a 2009 paper, so they are not directly comparable with the table values.
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 | Ni-Mn-Ga |
|---|---|
| Thermal behavior and safety | |
| Latent heat of the martensitic transition, x = 0 | 270 J/mol4 |
| Latent heat of the martensitic transition, x = 0.19Q column of Table I in the paper | 2260 J/mol |
| Temperature behavior | |
| Curie temperature, stoichiometric Ni2MnGa | 370 K1 |
| Martensitic transition temperature Tm, x = 0 (Ni2MnGa) | 201 K2 |
| Martensitic transition temperature Tm, x = 0.04Tm column of Table I in the paper | 237 K |
| Martensitic transition temperature Tm, x = 0.08Tm column of Table I in the paper | 265 K |
| Martensitic transition temperature Tm, x = 0.12Tm column of Table I in the paper | 294 K |
| Martensitic transition temperature Tm, x = 0.16Tm column of Table I in the paper | 315 K |
| Martensitic transition temperature Tm, x = 0.19 | 342 K3 |
| Martensitic transition temperature Ms, Ni48 Mn31 Ga21 | 301 K9 |
| Martensitic transition temperature Ms, Ni49.8 Mn28.5 Ga21.7 | 318 K10 |
| Other measurements | |
| Magnetically induced strain, Ni48 Mn31 Ga21 single crystal | 5.1 %5 |
| Magnetically induced strain, Ni49.8 Mn28.5 Ga21.7 single crystal | 6 %6 |
| Magnetically induced strain, Ni48.2 Mn30.8 Ga21 single crystal | 7.3 %7 |
| Magnetically induced strain, nonmodulated martensite single crystal | 0.17 %8 |
| Uniaxial anisotropy constant Ku at room temperature, Ni48 Mn31 Ga21 | 1.7 10^6 erg/cm³11 |
| Uniaxial anisotropy constant Ku at room temperature, Ni48.2 Mn30.8 Ga21 | 2.13 10^6 erg/cm³12 |
| Magnetic entropy change at the transition, field switched on | 9 J/kgK13 |
| Magnetic entropy change at the transition, field switched off | 11 J/kgK14 |
Why choose it, and why not
Good for
- Single-crystal magnetic actuators where stroke is set by a field, with 5.1 to 7.3 % strain in one review table.
- Magnetocaloric refrigerant studies near room temperature, with 9 and 11 J/kgK entropy changes in a 26 kOe field.
Watch out for
- Brittleness: the 2000 MRS-J paper names it as a main obstacle to practical use.
- Composition: Tm moves from 201 K to 342 K across the series.
- Cut position: a crystal cut from the middle of the boule gave no strain in the review.
- Hazards: the SDS codes used here come from a nickel alloy and gallium, not a Ni-Mn-Ga SDS.
Ni-Mn-Ga is a magnetically driven shape-memory Heusler alloy. Its strain is set by a magnetic field, not by heat, and its single crystals gave 5.1 to 7.3 % strain in one review table. The record still lacks density, elastic modulus, corrosion data, a Ni-Mn-Ga SDS, designations and any 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.
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Curie temperature, stoichiometric Ni2MnGa | Value stated in the text on the composition dependence of TC, from magnetization measurements reported in the paper | composition Ni2MnGa, x = 0note printed as about 370 K | — |
| 2 | Martensitic transition temperature Tm, x = 0 (Ni2MnGa) | Tm column of Table I in the paper, which gives the transition temperature for each composition | composition Ni2+xMn1-xGa, x = 0 | — |
| 3 | Martensitic transition temperature Tm, x = 0.19 | Tm column of Table I in the paper; at x = 0.18 to 0.19 the Curie temperature merges with Tm | composition Ni2+xMn1-xGa, x = 0.19 | — |
| 4 | Latent heat of the martensitic transition, x = 0 | Q column of Table I in the paper, which the text links to the latent heat used in the Clapeyron-Clausius analysis | composition Ni2+xMn1-xGa, x = 0 | — |
| 5 | Magnetically induced strain, Ni48 Mn31 Ga21 single crystal | MFIS column of Table I in the review, which collects single-crystal values; the table lists references 74 and 135 for this row | composition Ni48 Mn31 Ga21 (at.%), single crystal, single-variant martensitenote strain in the martensitic state set by variant reorientation in a magnetic field | — |
| 6 | Magnetically induced strain, Ni49.8 Mn28.5 Ga21.7 single crystal | MFIS column of Table I in the review; the table cites reference 119 for this row | composition Ni49.8 Mn28.5 Ga21.7 (at.%), single crystal | — |
| 7 | Magnetically induced strain, Ni48.2 Mn30.8 Ga21 single crystal | MFIS column of Table I in the review; the table cites reference 81 for this row | composition Ni48.2 Mn30.8 Ga21 (at.%), single crystal | — |
| 8 | Magnetically induced strain, nonmodulated martensite single crystal | Abstract value for a rotating field on a stress-free single crystal with nonmodulated martensite | composition Ni53.1 Mn26.6 Ga20.3 (composition as printed, no at.% stated), single crystal, stress-freefield rotating magnetic field, strength not stated in the abstract | — |
| 9 | Martensitic transition temperature Ms, Ni48 Mn31 Ga21 | Ms column of Table I in the review, shown with the MFIS value for the same row | composition Ni48 Mn31 Ga21 (at.%)note Ms as printed in Table I of the review | — |
| 10 | Martensitic transition temperature Ms, Ni49.8 Mn28.5 Ga21.7 | Ms column of Table I in the review, shown with the MFIS value for the same row | composition Ni49.8 Mn28.5 Ga21.7 (at.%)note Ms as printed in Table I of the review | — |
| 11 | Uniaxial anisotropy constant Ku at room temperature, Ni48 Mn31 Ga21 | Ku value given in the review text for single-variant single crystals of this composition, and in the Ku column of Table I | composition Ni48 Mn31 Ga21 (at.%), single-variant statetemperature room temperatureunit in source 10^6 erg/cm3 | — |
| 12 | Uniaxial anisotropy constant Ku at room temperature, Ni48.2 Mn30.8 Ga21 | Ku column of Table I in the review, with reference 81 | composition Ni48.2 Mn30.8 Ga21 (at.%)unit in source 10^6 erg/cm3 | — |
| 13 | Magnetic entropy change at the transition, field switched on | Largest entropy change in a 26 kOe field, as stated in the conference summary | composition Ni-Mn-Ga alloy (composition not stated on the page)field 26 kOetemperature 338 K on turning the field on | — |
| 14 | Magnetic entropy change at the transition, field switched off | Largest entropy change in a 26 kOe field on field removal, as stated in the conference summary | composition Ni-Mn-Ga alloy (composition not stated on the page)field 26 kOetemperature 344 K on turning the field off | — |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
Ni-Mn-Ga is a nickel alloy. The sources supplied here cover nickel-based alloy and gallium hazards, not a Ni-Mn-Ga supplier SDS.
- Codes found
- A nickel-based alloy SDS lists H317, H351, H372 and H410, and a gallium SDS lists H290, which may be corrosive to metals.
- Gap
- No safety data sheet for the Ni-Mn-Ga alloy itself was read in this run, so the codes above are a proxy.
If it fails
The sources name brittleness, composition shift and loss of strain as the main ways a Ni-Mn-Ga part stops working.
- Brittleness
- The 2000 MRS-J paper names inherent brittleness as one of the problems to overcome before practical use.
- Composition drift
- The martensitic transition temperature rises from 201 K at x = 0 to 342 K at x = 0.19, and the Curie temperature falls toward it.
Handling and storage
- Melting
- Ingots are arc melted under argon, homogenized at 1073 K for 48 to 72 hours, and quenched.
- Sample position
- A crystal cut from the middle of the boule gave no magnetically induced strain in the review, so cut position matters.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Brittlenesshigh severity | Ni-Mn-Ga Heusler alloys processed for actuatorsThe 2000 MRS-J paper calls inherent brittleness, together with lower martensitic transformation temperatures, a problem to be overcome before practical use. |
| Loss of strain from sample positionmoderate severity | Single crystal cut from the middle of the boule instead of its beginningFor samples cut from the middle of the single crystals no magnetically induced strain was observed, while a 6 % strain was seen in a sample cut from the beginning. |
| Composition shift of the transitionhigh severity | Excess nickel, x in Ni2+xMn1-xGa, from 0 toward 0.19Tm rises from 201 K to 342 K and the Curie temperature falls toward the same value, so at x = 0.18 to 0.19 the alloy goes from paramagnetic austenite to martensite through a structural transition. |
| No strain when the anisotropy is too weakmoderate severity | Magnetocrystalline anisotropy energy below the effective elastic modulus of the twin boundariesVariant reorientation needs the anisotropy energy density to exceed the effective elastic modulus of the displacement of martensitic domain boundaries, so weaker anisotropy gives less strain. |
Handling and storage
- Melt the alloy in an argon arc, then homogenize the ingot at 1073 K for 48 to 72 hours in argon and quench into room-temperature water.
- Check composition by EDX after melting, because the transition temperature moves with the Ni, Mn and Ga content.
- Treat gallium as corrosive to metals (H290) and follow the supplier SDS for the alloy.
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%
- Recycling
- USGS 2026: most secondary nickel was in the form of nickel content of stainless-steel scrap, and most recycled nickel was used to produce new alloys.
Manganese, world mine production 2025e (20,000 thousand t, manganese content; South Africa 7,600, Gabon 5,000, Ghana 2,000); shares calculated by Space Mushroom from the printed tonnages
Land-based manganese resources are large but irregularly distributed; world reserves 1,800,000 thousand t (USGS 2026)
- Top producers (2025)
- South Africa 38%, Gabon 25%, Ghana 10%
- Recycling
- USGS 2026: manganese was recycled incidentally as a constituent of ferrous and nonferrous scrap.
Gallium, world primary low-purity production 2024 (848,000 kg; China 839,000 kg, Japan 3,000 kg, Russia 6,000 kg); shares calculated by Space Mushroom from the printed kilograms
Gallium is produced mainly as a byproduct of bauxite processing; bauxite contains about 50 parts per million gallium (USGS 2026)
- Top producers (2024)
- China 98.9%, Russia 0.7%, Japan 0.4%
- Recycling
- USGS 2026: old scrap, none; substantial new scrap from GaAs device manufacture was reprocessed at one New York facility.
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
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spore: profile
id: nimnga-shape-memory
spore_version: 0.2
family: nickel-manganese-gallium-heusler
name: Nickel-manganese-gallium magnetic shape-memory alloy
abbreviation: Ni-Mn-Ga
role: magnetic shape-memory alloy for actuators and magnetocaloric cooling
category: metals
type: shape-memory-alloys
summary: |
Ni-Mn-Ga is a Heusler alloy of nickel, manganese and gallium, with stoichiometric Ni2MnGa as its reference composition. Unlike nitinol, which changes shape on heating, its martensite can be reoriented by a magnetic field. Single crystals of Ni48 Mn31 Ga21, Ni49.8 Mn28.5 Ga21.7 and Ni48.2 Mn30.8 Ga21 gave 5.1, 6.0 and 7.3 % magnetically induced strain in one review table. The Curie temperature of stoichiometric Ni2MnGa is about 370 K, and the martensitic transition temperature of the Ni2+xMn1-xGa series rises from 201 K at x = 0 to 342 K at x = 0.19.
best_for: Single-crystal actuators that must move by a magnetic field rather than by heating, with 5.1 to 7.3 % magnetically induced strain in the review table and a martensite that is magnetically controlled
weakest_at: Brittleness and a low martensitic transformation temperature. A 2000 MRS-J paper names both as the main obstacles to practical use, and strain is lost when the crystal is cut from the middle of the boule
identity:
formula: Ni2MnGa, stoichiometric Heusler alloy; the studied series is Ni2+xMn1-xGa with x from 0 to 0.19
source: khovailo2004
where: Abstract and composition formula Ni2+xMn1-xGa, 0 to 0.19; Ni2MnGa at x = 0 (introduction)
designations: []
tags:
environments: []
stresses: []
applications:
- mechanisms
- thermal-control
properties:
- benchmark: curie_temperature
label: Curie temperature, stoichiometric Ni2MnGa
value: 370
unit: K
scope: material
conditions:
composition: Ni2MnGa, x = 0
note: printed as about 370 K
method: Value stated in the text on the composition dependence of TC, from magnetization measurements reported in the paper
status: ground
source: khovailo2004
where: Text on composition dependence, sentence beginning The Curie temperature TC is about 370 K in stoichiometric composition
- benchmark: martensitic_transition_temperature
label: Martensitic transition temperature Tm, x = 0 (Ni2MnGa)
value: 201
unit: K
scope: material
conditions:
composition: Ni2+xMn1-xGa, x = 0
method: Tm column of Table I in the paper, which gives the transition temperature for each composition
status: ground
source: khovailo2004
where: Table I, Tm column, row x = 0
- benchmark: martensitic_transition_temperature
label: Martensitic transition temperature Tm, x = 0.04
value: 237
unit: K
scope: material
conditions:
composition: Ni2+xMn1-xGa, x = 0.04
method: Tm column of Table I in the paper
status: ground
source: khovailo2004
where: Table I, Tm column, row x = 0.04
- benchmark: martensitic_transition_temperature
label: Martensitic transition temperature Tm, x = 0.08
value: 265
unit: K
scope: material
conditions:
composition: Ni2+xMn1-xGa, x = 0.08
method: Tm column of Table I in the paper
status: ground
source: khovailo2004
where: Table I, Tm column, row x = 0.08
- benchmark: martensitic_transition_temperature
label: Martensitic transition temperature Tm, x = 0.12
value: 294
unit: K
scope: material
conditions:
composition: Ni2+xMn1-xGa, x = 0.12
method: Tm column of Table I in the paper
status: ground
source: khovailo2004
where: Table I, Tm column, row x = 0.12
- benchmark: martensitic_transition_temperature
label: Martensitic transition temperature Tm, x = 0.16
value: 315
unit: K
scope: material
conditions:
composition: Ni2+xMn1-xGa, x = 0.16
method: Tm column of Table I in the paper
status: ground
source: khovailo2004
where: Table I, Tm column, row x = 0.16
- benchmark: martensitic_transition_temperature
label: Martensitic transition temperature Tm, x = 0.19
value: 342
unit: K
scope: material
conditions:
composition: Ni2+xMn1-xGa, x = 0.19
method: Tm column of Table I in the paper; at x = 0.18 to 0.19 the Curie temperature merges with Tm
status: ground
source: khovailo2004
where: Table I, Tm column, row x = 0.19
- benchmark: latent_heat_martensitic_transition
label: Latent heat of the martensitic transition, x = 0
value: 270
unit: J/mol
scope: material
conditions:
composition: Ni2+xMn1-xGa, x = 0
method: Q column of Table I in the paper, which the text links to the latent heat used in the Clapeyron-Clausius analysis
status: ground
source: khovailo2004
where: Table I, Q column, row x = 0
- benchmark: latent_heat_martensitic_transition
label: Latent heat of the martensitic transition, x = 0.19
value: 2260
unit: J/mol
scope: material
conditions:
composition: Ni2+xMn1-xGa, x = 0.19
method: Q column of Table I in the paper
status: ground
source: khovailo2004
where: Table I, Q column, row x = 0.19
- benchmark: magnetic_field_induced_strain
label: Magnetically induced strain, Ni48 Mn31 Ga21 single crystal
value: 5.1
unit: '%'
scope: material
conditions:
composition: Ni48 Mn31 Ga21 (at.%), single crystal, single-variant martensite
note: strain in the martensitic state set by variant reorientation in a magnetic field
method: MFIS column of Table I in the review, which collects single-crystal values; the table lists references 74 and 135 for this row
status: ground
source: vasil2003
where: Table I, Magnetically induced strains in Ni2+x+yMn1-xGa1-y alloys, row Ni48 Mn31 Ga21
- benchmark: magnetic_field_induced_strain
label: Magnetically induced strain, Ni49.8 Mn28.5 Ga21.7 single crystal
value: 6
unit: '%'
scope: material
conditions:
composition: Ni49.8 Mn28.5 Ga21.7 (at.%), single crystal
method: MFIS column of Table I in the review; the table cites reference 119 for this row
status: ground
source: vasil2003
where: Table I, Magnetically induced strains, row Ni49.8 Mn28.5 Ga21.7
- benchmark: magnetic_field_induced_strain
label: Magnetically induced strain, Ni48.2 Mn30.8 Ga21 single crystal
value: 7.3
unit: '%'
scope: material
conditions:
composition: Ni48.2 Mn30.8 Ga21 (at.%), single crystal
method: MFIS column of Table I in the review; the table cites reference 81 for this row
status: ground
source: vasil2003
where: Table I, Magnetically induced strains, row Ni48.2 Mn30.8 Ga21
- benchmark: magnetic_field_induced_strain
label: Magnetically induced strain, nonmodulated martensite single crystal
value: 0.17
unit: '%'
scope: material
conditions:
composition: Ni53.1 Mn26.6 Ga20.3 (composition as printed, no at.% stated), single crystal, stress-free
field: rotating magnetic field, strength not stated in the abstract
method: Abstract value for a rotating field on a stress-free single crystal with nonmodulated martensite
status: ground
source: chernenko2009
where: Abstract, first sentence
- benchmark: martensitic_transition_temperature
label: Martensitic transition temperature Ms, Ni48 Mn31 Ga21
value: 301
unit: K
scope: material
conditions:
composition: Ni48 Mn31 Ga21 (at.%)
note: Ms as printed in Table I of the review
method: Ms column of Table I in the review, shown with the MFIS value for the same row
status: ground
source: vasil2003
where: Table I, Ms column, row Ni48 Mn31 Ga21
- benchmark: martensitic_transition_temperature
label: Martensitic transition temperature Ms, Ni49.8 Mn28.5 Ga21.7
value: 318
unit: K
scope: material
conditions:
composition: Ni49.8 Mn28.5 Ga21.7 (at.%)
note: Ms as printed in Table I of the review
method: Ms column of Table I in the review, shown with the MFIS value for the same row
status: ground
source: vasil2003
where: Table I, Ms column, row Ni49.8 Mn28.5 Ga21.7
- benchmark: magnetocrystalline_anisotropy_constant
label: Uniaxial anisotropy constant Ku at room temperature, Ni48 Mn31 Ga21
value: 1.7
unit: 10^6 erg/cm3
scope: material
conditions:
composition: Ni48 Mn31 Ga21 (at.%), single-variant state
temperature: room temperature
unit_in_source: 10^6 erg/cm3
method: Ku value given in the review text for single-variant single crystals of this composition, and in the Ku column of Table I
status: ground
source: vasil2003
where: Section on magnetocrystalline anisotropy, paragraph beginning with the values of Ku at room temperature
- benchmark: magnetocrystalline_anisotropy_constant
label: Uniaxial anisotropy constant Ku at room temperature, Ni48.2 Mn30.8 Ga21
value: 2.13
unit: 10^6 erg/cm3
scope: material
conditions:
composition: Ni48.2 Mn30.8 Ga21 (at.%)
unit_in_source: 10^6 erg/cm3
method: Ku column of Table I in the review, with reference 81
status: ground
source: vasil2003
where: Table I, Ku column, row Ni48.2 Mn30.8 Ga21
- benchmark: magnetic_entropy_change
label: Magnetic entropy change at the transition, field switched on
value: 9
unit: J/kgK
scope: material
conditions:
composition: Ni-Mn-Ga alloy (composition not stated on the page)
field: 26 kOe
temperature: 338 K on turning the field on
method: Largest entropy change in a 26 kOe field, as stated in the conference summary
status: ground
source: aliev2005
where: Summary, first sentence on entropy changes
- benchmark: magnetic_entropy_change
label: Magnetic entropy change at the transition, field switched off
value: 11
unit: J/kgK
scope: material
conditions:
composition: Ni-Mn-Ga alloy (composition not stated on the page)
field: 26 kOe
temperature: 344 K on turning the field off
method: Largest entropy change in a 26 kOe field on field removal, as stated in the conference summary
status: ground
source: aliev2005
where: Summary, second sentence on entropy changes
corrosion: []
risks:
hazards:
- text: 'Gallium, the Ga constituent: the supplier safety data sheet lists H290 (may be corrosive to metals) with signal word Warning, and P234, P390 and P406.'
ghs:
- H290
source: sds-ga
where: Section 2, hazard statements; precautionary statements
- text: 'Nickel-based alloy SDS, the closest found for a nickel-rich alloy and not Ni-Mn-Ga itself: skin sensitisation Category 1 (H317), carcinogenicity Category 2 (H351), STOT repeated exposure Category 1 (H372) and aquatic chronic Category 1 (H410).'
ghs:
- H317
- H351
- H372
- H410
source: sds-ni-alloy
where: Section 2.1, classification of the substance or mixture
failure_risks:
- mode: Brittleness
trigger: Ni-Mn-Ga Heusler alloys processed for actuators
consequence: The 2000 MRS-J paper calls inherent brittleness, together with lower martensitic transformation temperatures, a problem to be overcome before practical use.
severity: high
source: tsuchiya2000
where: Introduction, first paragraph
- mode: Loss of strain from sample position
trigger: Single crystal cut from the middle of the boule instead of its beginning
consequence: For samples cut from the middle of the single crystals no magnetically induced strain was observed, while a 6 % strain was seen in a sample cut from the beginning.
severity: moderate
source: vasil2003
where: Section on magnetically induced strains, paragraph after Table I reference 141
- mode: Composition shift of the transition
trigger: Excess nickel, x in Ni2+xMn1-xGa, from 0 toward 0.19
consequence: Tm rises from 201 K to 342 K and the Curie temperature falls toward the same value, so at x = 0.18 to 0.19 the alloy goes from paramagnetic austenite to martensite through a structural transition.
severity: high
source: khovailo2004
where: Introduction and Table I
- mode: No strain when the anisotropy is too weak
trigger: Magnetocrystalline anisotropy energy below the effective elastic modulus of the twin boundaries
consequence: Variant reorientation needs the anisotropy energy density to exceed the effective elastic modulus of the displacement of martensitic domain boundaries, so weaker anisotropy gives less strain.
severity: moderate
source: vasil2003
where: Section on magnetically induced strains, paragraph beginning This occurs if the magnetocrystalline anisotropy energy density exceeds
side_effects: []
handling:
- text: Melt the alloy in an argon arc, then homogenize the ingot at 1073 K for 48 to 72 hours in argon and quench into room-temperature water.
source: tsuchiya2000
where: Experimental section
- text: Check composition by EDX after melting, because the transition temperature moves with the Ni, Mn and Ga content.
source: tsuchiya2000
where: Experimental section, composition analysis
- text: Treat gallium as corrosive to metals (H290) and follow the supplier SDS for the alloy.
source: sds-ga
where: Section 2
mitigations: []
uses:
- application: mechanisms
device: Magnetic actuators and magnetomechanical parts
example: The 2000 MRS-J paper calls Ni-Mn-Ga a good candidate for magnetic actuator materials, because the alloy shows large twinning magnetostriction in its martensite phase.
source: tsuchiya2000
where: Introduction, first paragraph
- application: thermal-control
device: Magnetocaloric refrigerant
example: A 2005 conference paper on Ni-Mn-Ga reports magnetic entropy changes of 9 J/kgK at 338 K and 11 J/kgK at 344 K in a 26 kOe field, the basis for magnetic refrigeration at room temperature.
source: aliev2005
where: Summary
story:
risk_groups:
- title: For people
lead: Ni-Mn-Ga is a nickel alloy. The sources supplied here cover nickel-based alloy and gallium hazards, not a Ni-Mn-Ga supplier SDS.
level: 2
verdict: Nickel and gallium hazards
points:
- label: Codes found
line: A nickel-based alloy SDS lists H317, H351, H372 and H410, and a gallium SDS lists H290, which may be corrosive to metals.
- label: Gap
line: No safety data sheet for the Ni-Mn-Ga alloy itself was read in this run, so the codes above are a proxy.
- title: If it fails
lead: The sources name brittleness, composition shift and loss of strain as the main ways a Ni-Mn-Ga part stops working.
level: 2
verdict: Brittleness and composition
points:
- label: Brittleness
line: The 2000 MRS-J paper names inherent brittleness as one of the problems to overcome before practical use.
- label: Composition drift
line: The martensitic transition temperature rises from 201 K at x = 0 to 342 K at x = 0.19, and the Curie temperature falls toward it.
- title: Handling and storage
points:
- label: Melting
line: Ingots are arc melted under argon, homogenized at 1073 K for 48 to 72 hours, and quenched.
- label: Sample position
line: A crystal cut from the middle of the boule gave no magnetically induced strain in the review, so cut position matters.
why: Ni-Mn-Ga is a ferromagnetic shape-memory alloy. Its martensite can be reoriented by a magnetic field, so it can change shape fast without a heating cycle. Single crystals show 5.1 to 7.3 % magnetically induced strain in one review table, and the Curie temperature of stoichiometric Ni2MnGa is about 370 K.
uses:
- where: Magnetic actuators
line: The 2000 MRS-J paper calls Ni-Mn-Ga a good candidate for magnetic actuator materials, and the 2003 review notes that actuators and sensors based on this class of alloy need more durability first.
- where: Magnetocaloric cooling
line: A 2005 conference paper reports 9 J/kgK at 338 K and 11 J/kgK at 344 K in a 26 kOe field.
can_do:
- label: Change shape by field
line: Single crystals of Ni48 Mn31 Ga21, Ni49.8 Mn28.5 Ga21.7 and Ni48.2 Mn30.8 Ga21 gave 5.1, 6.0 and 7.3 % magnetically induced strain.
value: 5.1 to 7.3 %
- label: Work near room temperature
line: The Curie temperature of stoichiometric Ni2MnGa is about 370 K, and the transition temperature Tm of the series runs from 201 K to 342 K.
value: 201 to 342 K
- label: Cool by magnetic entropy change
line: A magnetic entropy change of 9 J/kgK at 338 K was measured in a 26 kOe field, and 11 J/kgK at 344 K when the field was removed.
value: 9 and 11 J/kgK
compare: Among the Ni2+xMn1-xGa series, the martensitic transition temperature rises with nickel content, from 201 K at x = 0 to 342 K at x = 0.19, while the Curie temperature falls toward it. Strain values come from single crystals in one review table and from a nonmodulated single crystal in a 2009 paper, so they are not directly comparable with the table values.
compare_rows:
- label: Curie temperature
benchmark: curie_temperature
- label: Martensitic transition temperature
benchmark: martensitic_transition_temperature
- label: Magnetic field induced strain
benchmark: magnetic_field_induced_strain
handling:
- Homogenize the ingot at 1073 K for 48 to 72 hours under argon, then quench.
- Check the composition by EDX, since Tm moves with composition.
- Treat gallium as corrosive to metals (H290) and follow the supplier SDS.
good_for:
- Single-crystal magnetic actuators where stroke is set by a field, with 5.1 to 7.3 % strain in one review table.
- Magnetocaloric refrigerant studies near room temperature, with 9 and 11 J/kgK entropy changes in a 26 kOe field.
watch_out:
- 'Brittleness: the 2000 MRS-J paper names it as a main obstacle to practical use.'
- 'Composition: Tm moves from 201 K to 342 K across the series.'
- 'Cut position: a crystal cut from the middle of the boule gave no strain in the review.'
- 'Hazards: the SDS codes used here come from a nickel alloy and gallium, not a Ni-Mn-Ga SDS.'
verdict: Ni-Mn-Ga is a magnetically driven shape-memory Heusler alloy. Its strain is set by a magnetic field, not by heat, and its single crystals gave 5.1 to 7.3 % strain in one review table. The record still lacks density, elastic modulus, corrosion data, a Ni-Mn-Ga SDS, designations and any space-environment data, so it is a draft.
recipe:
line: Ni-Mn-Ga is made by argon arc melting of the three metals, followed by homogenization at 1073 K for 48 to 72 hours in argon and quenching into room-temperature water (Tsuchiya 2000). Composition is set by the Ni, Mn and Ga ratio, with stoichiometric Ni2MnGa as the reference.
parts:
- name: Nickel
symbol: Ni
role: Sets the transition temperature and Curie temperature; excess nickel raises Tm and lowers TC
share_note: 2 of 4 formula positions in stoichiometric Ni2MnGa (x = 0), then Ni2+xMn1-xGa to x = 0.19
source: khovailo2004
where: Formula Ni2+xMn1-xGa, Introduction
- name: Manganese
symbol: Mn
role: Carries the magnetic moment of the Heusler lattice and sets the Mn-rich compositions with the largest strain
share_note: 1 of 4 formula positions in stoichiometric Ni2MnGa (x = 0); lower in the Ni-rich series
source: khovailo2004
where: Formula Ni2+xMn1-xGa, Introduction
- name: Gallium
symbol: Ga
role: Heusler third element; its content is fixed by the Mn-Ni balance in the studied series
share_note: 1 of 4 formula positions in stoichiometric Ni2MnGa (x = 0)
source: khovailo2004
where: Formula Ni2MnGa, Introduction
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
critical_lists: []
recycling: 'USGS 2026: most secondary nickel was in the form of nickel content of stainless-steel scrap, and most recycled nickel was used to produce new alloys.'
substitutes: []
source: usgs-ni
where: World Mine Production and Reserves table, 2024 and 2025e columns
- subject: Manganese, world mine production 2025e (20,000 thousand t, manganese content; South Africa 7,600, Gabon 5,000, Ghana 2,000); shares calculated by Space Mushroom from the printed tonnages
abundance: Land-based manganese resources are large but irregularly distributed; world reserves 1,800,000 thousand t (USGS 2026)
producers:
- country: South Africa
share_percent: 38
year: 2025
- country: Gabon
share_percent: 25
year: 2025
- country: Ghana
share_percent: 10
year: 2025
critical_lists: []
recycling: 'USGS 2026: manganese was recycled incidentally as a constituent of ferrous and nonferrous scrap.'
substitutes: []
source: usgs-mn
where: World Mine Production (manganese content) and Reserves table, 2025e column
- subject: Gallium, world primary low-purity production 2024 (848,000 kg; China 839,000 kg, Japan 3,000 kg, Russia 6,000 kg); shares calculated by Space Mushroom from the printed kilograms
abundance: Gallium is produced mainly as a byproduct of bauxite processing; bauxite contains about 50 parts per million gallium (USGS 2026)
producers:
- country: China
share_percent: 98.9
year: 2024
- country: Russia
share_percent: 0.7
year: 2024
- country: Japan
share_percent: 0.4
year: 2024
critical_lists: []
recycling: 'USGS 2026: old scrap, none; substantial new scrap from GaAs device manufacture was reprocessed at one New York facility.'
substitutes: []
source: usgs-ga
where: World Low-Purity Production table, 2024 column; World Resources paragraph
documents:
- title: Shape memory ferromagnets (Vasil'ev et al., arXiv cond-mat/0311433, 2003)
type: paper
url: https://arxiv.org/pdf/cond-mat/0311433
year: 2003
- title: Magnetic properties and magnetostructural phase transitions in Ni2+xMn1-xGa shape memory alloys (Khovailo et al., arXiv cond-mat/0405134, 2004)
type: paper
url: https://arxiv.org/pdf/cond-mat/0405134
year: 2004
- title: Large Magnetic-Field-Induced Strains in Ni-Mn-Ga Nonmodulated Martensite (Chernenko et al., Applied Physics Letters 2009)
type: paper
url: https://scholarworks.boisestate.edu/mse_facpubs/40
year: 2009
- title: Magnetocaloric effect in Ni-Mn-Ga Heusler alloys (Aliev et al., 2005)
type: paper
url: https://iifiir.org/en/fridoc/magnetocaloric-effect-in-ni-mn-ga-heusler-alloys-22416
year: 2005
- title: Effect of Fourth Elements on Phase Transformations in Ni-Mn-Ga Heusler Alloys (Tsuchiya et al., Trans. MRS-J 25, 2000)
type: paper
url: https://www.mrs-j.org/pub/tmrsj/vol25_no2/vol25_no2_517.pdf
year: 2000
- title: Structural, Thermal and Magnetic Characterization of Polycrystalline Ni-Mn-Ga Ferromagnetic Shape Memory Alloys (Materials Research, 2023)
type: paper
url: https://www.scielo.br/j/mr/a/kgNcGQ55wgqyJngcwjVm8Qk/?lang=en
year: 2023
- 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: Gallium'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-gallium.pdf
year: 2026
- title: Gallium safety data sheet (Angstrom Sciences, CAS 7440-55-3)
type: sds
url: https://angstromsciences.com/wp-content/uploads/files/SDS/Gallium.pdf
- title: Nickel Based Metal Alloys safety data sheet (Greenville Metals, PCC Forged Products)
type: sds
url: https://www.pccforgedproducts.com/documents/greenville/sds/nickel-based-metal-alloys-sds.pdf
gaps:
- No density or elastic modulus for Ni-Mn-Ga was read in a source in this run. The Ni2MnGa searches returned no density, and the Vasil'ev and Khovailo papers give none.
- No corrosion, oxidation or ageing data for Ni-Mn-Ga was found, so the corrosion list is empty.
- No UNS, EN, JIS, AISI, ASTM or other designation for Ni-Mn-Ga was printed in a source read in this run, so designations is empty.
- No safety data sheet for the Ni-Mn-Ga alloy itself was read. The nickel-based alloy SDS (Greenville Metals) is a related product, not the same grade, and the Mn SDS was not read.
- The Wikipedia Ni-Mn-Ga page was not used for values. The Heusler and magnetic shape-memory Wikipedia pages are secondary and were read only for composition and history.
- The Springer review (s40830-024-00510-z) redirected to a sign-in page, and the PubChem gallium page returned a verification page, so no PubChem GHS entry was read.
- The Dubenko et al. 2012 abstract gives magnetic entropy change values for Ni-Mn-based Heusler alloys with In, Sn and Sb, not Ni-Mn-Ga, so none of its numbers were used.
- The full table of Materials Research 2023 (Batista et al.) was not read; only its abstract was, which gives compositions and phases but no property values.
- The Ni-Mn-Ga temperature range, fatigue life, output stress and cycling figures in the Wikipedia magnetic shape-memory page are secondary, and were not entered as values.
- No space-environment data (outgassing, atomic oxygen, radiation, thermal cycling in orbit) for Ni-Mn-Ga was found in a source read in this run.
- 'Critical-mineral list status for nickel, manganese and gallium was not confirmed: the USGS texts give no list, and the gallium text does not name one.'
- 'Custom property names used because no canonical name exists: martensitic_transition_temperature, latent_heat_martensitic_transition, magnetic_field_induced_strain, magnetocrystalline_anisotropy_constant and magnetic_entropy_change.'
- Table I values in the Vasil'ev review are from a 2003 review table and are cited to the original reference numbers, not re-measured here. The supply shares are calculated by Space Mushroom from printed tonnages.
sources:
khovailo2004:
title: Magnetic properties and magnetostructural phase transitions in Ni2+xMn1-xGa shape memory alloys (Khovailo et al., Phys. Rev. B 70, 174413, 2004)
url: https://arxiv.org/pdf/cond-mat/0405134
year: 2004
kind: paper
license: arXiv preprint (cited, not reproduced)
vasil2003:
title: Shape memory ferromagnets (Vasil'ev et al., arXiv cond-mat/0311433, 2003)
url: https://arxiv.org/pdf/cond-mat/0311433
year: 2003
kind: paper
license: arXiv preprint (cited, not reproduced)
chernenko2009:
title: Large Magnetic-Field-Induced Strains in Ni-Mn-Ga Nonmodulated Martensite (Chernenko, Chmielus, Mullner, Applied Physics Letters 95, 104103, 2009)
url: https://scholarworks.boisestate.edu/mse_facpubs/40
year: 2009
kind: paper
license: author repository (cited, not reproduced)
aliev2005:
title: Magnetocaloric effect in Ni-Mn-Ga Heusler alloys (Aliev et al., 1st International Conference on Magnetic Refrigeration at Room Temperature, 2005)
url: https://iifiir.org/en/fridoc/magnetocaloric-effect-in-ni-mn-ga-heusler-alloys-22416
year: 2005
kind: paper
license: IIR document (cited, not reproduced)
tsuchiya2000:
title: Effect of Fourth Elements on Phase Transformations in Ni-Mn-Ga Heusler Alloys (Tsuchiya et al., Trans. Mater. Res. Soc. Jpn. 25, 2000)
url: https://www.mrs-j.org/pub/tmrsj/vol25_no2/vol25_no2_517.pdf
year: 2000
kind: paper
license: open access (cited, not reproduced)
batista2023:
title: Structural, Thermal and Magnetic Characterization of Polycrystalline Ni-Mn-Ga Ferromagnetic Shape Memory Alloys (Batista et al., Materials Research 26, 2023)
url: https://www.scielo.br/j/mr/a/kgNcGQ55wgqyJngcwjVm8Qk/?lang=en
year: 2023
kind: paper
license: open access (cited, not reproduced)
wiki-msma:
title: Magnetic shape-memory alloy, Wikipedia (composition and history only)
url: https://en.wikipedia.org/wiki/Magnetic_shape-memory_alloy
kind: web
license: CC BY-SA 4.0 (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-mn:
title: Mineral Commodity Summaries 2026, Manganese (USGS, February 2026)
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-manganese.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-ga:
title: Mineral Commodity Summaries 2026, Gallium (USGS, February 2026)
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-gallium.pdf
year: 2026
kind: report
license: public domain (USGS)
sds-ga:
title: Gallium safety data sheet (Angstrom Sciences, CAS 7440-55-3)
url: https://angstromsciences.com/wp-content/uploads/files/SDS/Gallium.pdf
kind: datasheet
license: manufacturer safety data sheet (cited, not reproduced)
sds-ni-alloy:
title: Nickel Based Metal Alloys safety data sheet (Greenville Metals, PCC Forged Products)
url: https://www.pccforgedproducts.com/documents/greenville/sds/nickel-based-metal-alloys-sds.pdf
kind: datasheet
license: manufacturer safety data sheet (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-10-26'
review:
status: draft
method: assistant
checked_values: 19
unreachable: 3
caveats: 5
note: 'Values were read by an AI assistant on 2026-10-26 from the papers, reports and safety data sheets named in each entry. Unreachable: the Springer review (sign-in redirect), the PubChem gallium page (verification page), and the Sigma-Aldrich SDS (timeout). Caveats: the hazard codes come from a nickel-based alloy SDS, not a Ni-Mn-Ga SDS; the Table I values are from a 2003 review and cite original references; the magnetocaloric numbers come from a conference summary with no composition; the strain values are for single crystals and a nonmodulated crystal, not comparable; the supply shares are calculated.'
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.