spore: profile
id: magnesium-ev31a
spore_version: 0.2
family: magnesium-alloys
name: Magnesium alloy EV31A (Elektron 21)
abbreviation: EV31A
role: heat-treatable casting alloy
category: metals
type: magnesium
summary: |
  EV31A, also sold as Elektron 21, is a heat-treatable magnesium casting alloy with neodymium, gadolinium, zinc and zirconium. Its maker, Magnesium Elektron (now Luxfer MEL), rates it for use up to 200 degC and gives a T6 treatment of 8 hours at 520 degC, a quench, then 16 hours at 200 degC. A 2006 Polish study of the as-cast alloy measured 99 MPa yield and 192 MPa tensile strength at 20 degC, below the norm values printed in that study, so heat treatment is needed to reach the rated properties.
best_for: Sand castings that must keep strength up to 200 degC, such as transmission and gearbox housings. The maker names motorsport and aerospace use, and a Bell Helicopter abstract describes rotorcraft transmission housings.
weakest_at: Strength depends on the T6 heat treatment, since the as-cast values in the Polish study were below the norms. No immersion corrosion data for this alloy was read, and the GHS fire statements apply to magnesium metal.
identity:
  formula: 'Mg-Nd-Gd-Zn-Zr casting alloy: Nd 2.6 to 3.1 wt%, Gd 1.0 to 1.7 wt%, Zn 0.2 to 0.5 wt%, Zr saturated, Mg balance (manufacturer datasheet). Polish study sample: Nd 2.7, Gd 1.2, Zn 0.4, Zr 0.49, Mn 0.001, Fe 0.003, Ag below 0.01, total rare earths 4.2 wt%, Mg balance.'
  designations:
    - system: Trade name
      code: Elektron 21
      source: luxfer-ds455
      where: Datasheet title, DS 455 Elektron 21
    - system: Name
      code: EV31A
      source: polsl-ev31a
      where: 'Section 2 (Material), first sentence: Elektron 21 (EV31A)'
    - system: UNS
      code: M12310
      source: luxfer-ds455
      where: Specifications list, UNS row (printed against Elektron 21)
    - system: AMS
      code: '4429'
      source: luxfer-ds455
      where: Specifications list
    - system: ASTM
      code: B80
      source: luxfer-ds455
      where: Specifications list
    - system: ISO
      code: MC65410
      note: ISO 16220 designation
      source: luxfer-ds455
      where: Specifications list, ISO 16220 row
  source: luxfer-ds455
  where: Chemical composition table, Specifications list and Heat treatment section of DS 455. Sample composition from Table 1 of the Polish study (polsl-ev31a). The link between Elektron 21 and EV31A is the Polish study's own wording.
tags:
  environments: []
  stresses: []
  applications:
    - mechanisms
    - structures
properties:
  - benchmark: density
    value: 1.82
    unit: g/cm3
    scope: material
    conditions:
      temperature: not stated
      basis: printed as specific gravity; read here as density, same number
    method: Physical properties table of the manufacturer datasheet
    status: ground
    source: luxfer-ds455
    where: Physical properties table, Specific gravity row
  - benchmark: melting_point
    label: Melting range
    value: 545
    value_high: 640
    bound: range
    unit: °C
    scope: material
    conditions:
      basis: range as printed on the datasheet
    method: Physical properties table of the manufacturer datasheet
    status: ground
    source: luxfer-ds455
    where: Physical properties table, Melting range row
  - benchmark: specific_heat
    value: 1086
    unit: J/(kg·K)
    scope: material
    conditions:
      temperature: not stated
      unit_in_source: J kg-1 K-1
    method: Physical properties table of the manufacturer datasheet
    status: ground
    source: luxfer-ds455
    where: Physical properties table, Specific heat row
  - benchmark: thermal_conductivity
    value: 116
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: not stated
      unit_in_source: W m-1 K-1
    method: Physical properties table of the manufacturer datasheet
    status: ground
    source: luxfer-ds455
    where: Physical properties table, Thermal conductivity row
  - benchmark: cte
    label: Coefficient of thermal expansion
    value: 26.3
    unit: ppm/K
    scope: material
    conditions:
      temperature_range: not stated on the datasheet
      unit_in_source: x 10-6 K-1 (same as ppm/K)
    method: Physical properties table of the manufacturer datasheet
    status: ground
    source: luxfer-ds455
    where: Physical properties table, Coefficient of thermal expansion row
  - benchmark: elastic_modulus
    value: 44.8
    unit: GPa
    scope: material
    conditions:
      temper: not stated on the row
      unit_in_source: 44.8 x 10^3 MPa
    method: Physical properties table of the manufacturer datasheet; printed in MPa and converted to GPa (44.8 x 10^3 MPa = 44.8 GPa)
    status: ground
    source: luxfer-ds455
    where: Physical properties table, Modulus of elasticity row
  - benchmark: poisson_ratio
    label: Poisson's ratio
    value: 0.27
    unit: '-'
    scope: material
    conditions:
      temperature: not stated
    method: Physical properties table of the manufacturer datasheet
    status: ground
    source: luxfer-ds455
    where: Physical properties table, Poissons ratio row
  - benchmark: electrical_resistivity
    value: 94.6
    unit: nΩm
    scope: material
    conditions:
      temperature: not stated
    method: Physical properties table of the manufacturer datasheet (printed as nΩm)
    status: ground
    source: luxfer-ds455
    where: Physical properties table, Electrical resistivity row
  - benchmark: hardness_brinell
    label: Brinell hardness
    value: 65
    value_high: 75
    bound: range
    unit: HB
    scope: material
    conditions:
      temper: not stated on the row
    method: Physical properties table of the manufacturer datasheet
    status: ground
    source: luxfer-ds455
    where: Physical properties table, Brinell hardness row
    note: Not in spores/property-canon.yaml; the snake_case name hardness_brinell is used, as in the AZ31B profile.
  - benchmark: yield_strength
    label: 0.2% proof stress, minimum specification
    value: 145
    unit: MPa
    scope: material
    conditions:
      basis: minimum specification tensile properties (design data), not a typical value
      temper: T6 casting (the datasheet heat treatment for castings)
    method: Design data table of the manufacturer datasheet
    status: ground
    source: luxfer-ds455
    where: Design data, Minimum specification tensile properties, 0.2% proof stress row
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, minimum specification
    value: 248
    unit: MPa
    scope: material
    conditions:
      basis: minimum specification tensile properties (design data), not a typical value
      temper: T6 casting (the datasheet heat treatment for castings)
    method: Design data table of the manufacturer datasheet
    status: ground
    source: luxfer-ds455
    where: Design data, Minimum specification tensile properties, Tensile strength row
  - benchmark: elongation_at_break
    label: Elongation, minimum specification
    value: 2
    unit: '%'
    scope: material
    conditions:
      basis: minimum specification tensile properties (design data)
      temper: T6 casting (the datasheet heat treatment for castings)
    method: Design data table of the manufacturer datasheet
    status: ground
    source: luxfer-ds455
    where: Design data, Minimum specification tensile properties, Elongation row
  - benchmark: yield_strength
    label: 0.2% proof stress, typical at ambient temperature
    value: 170
    unit: MPa
    scope: material
    conditions:
      temperature: ambient (printed as ambient)
      temper: not printed on the row; the datasheet heat treatment for castings is T6
    method: Ambient temperature mechanical properties, typical tensile properties (manufacturer datasheet)
    status: ground
    source: luxfer-ds455
    where: Ambient temperature mechanical properties, Typical tensile properties, 0.2% proof stress row
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, typical at ambient temperature
    value: 280
    unit: MPa
    scope: material
    conditions:
      temperature: ambient (printed as ambient)
      temper: not printed on the row; the datasheet heat treatment for castings is T6
    method: Ambient temperature mechanical properties, typical tensile properties (manufacturer datasheet)
    status: ground
    source: luxfer-ds455
    where: Ambient temperature mechanical properties, Typical tensile properties, Tensile strength row
  - benchmark: elongation_at_break
    label: Elongation, typical at ambient temperature
    value: 5
    unit: '%'
    scope: material
    conditions:
      temperature: ambient (printed as ambient)
      temper: not printed on the row; the datasheet heat treatment for castings is T6
    method: Ambient temperature mechanical properties, typical tensile properties (manufacturer datasheet)
    status: ground
    source: luxfer-ds455
    where: Ambient temperature mechanical properties, Typical tensile properties, Elongation row
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, typical at -35 °C
    value: 270
    unit: MPa
    scope: material
    conditions:
      temperature: '-35 °C'
      temper: not printed on the row
    method: Low temperature mechanical properties, typical values (manufacturer datasheet)
    status: ground
    source: luxfer-ds455
    where: Low temperature mechanical properties, Typical mechanical properties at -35 °C, Ultimate tensile strength row
  - benchmark: elongation_at_break
    label: Elongation, typical at -35 °C
    value: 7
    unit: '%'
    scope: material
    conditions:
      temperature: '-35 °C'
      temper: not printed on the row
    method: Low temperature mechanical properties, typical values (manufacturer datasheet)
    status: ground
    source: luxfer-ds455
    where: Low temperature mechanical properties, Typical mechanical properties at -35 °C, Elongation row
  - benchmark: yield_strength
    label: 0.2% proof stress, as cast, 20 °C (study sample, not heat treated)
    value: 99
    unit: MPa
    scope: material
    conditions:
      temper: as cast, not heat treated
      temperature: 20 °C
      basis: one sample from the Polish study, tested on an MTS-810 machine
    method: Mechanical properties table of the Polish study (Table 3, Re and Rm columns)
    status: ground
    source: polsl-ev31a
    where: Table 3, 20 °C row, R0,2 column
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, as cast, 20 °C (study sample, not heat treated)
    value: 192
    unit: MPa
    scope: material
    conditions:
      temper: as cast, not heat treated
      temperature: 20 °C
      basis: one sample from the Polish study, tested on an MTS-810 machine
    method: Mechanical properties table of the Polish study (Table 3, Rm column)
    status: ground
    source: polsl-ev31a
    where: Table 3, 20 °C row, Rm column
  - benchmark: elongation_at_break
    label: Elongation A5, as cast, 20 °C (study sample, not heat treated)
    value: 14.6
    unit: '%'
    scope: material
    conditions:
      temper: as cast, not heat treated
      temperature: 20 °C
    method: Mechanical properties table of the Polish study (Table 3, A5 column)
    status: ground
    source: polsl-ev31a
    where: Table 3, 20 °C row, A5 column
  - benchmark: yield_strength
    label: 0.2% proof stress, as cast, 200 °C (study sample, not heat treated)
    value: 69
    unit: MPa
    scope: material
    conditions:
      temper: as cast, not heat treated
      temperature: 200 °C
    method: Mechanical properties table of the Polish study (Table 3, Re column)
    status: ground
    source: polsl-ev31a
    where: Table 3, 200 °C row, R0,2 column
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, as cast, 200 °C (study sample, not heat treated)
    value: 168
    unit: MPa
    scope: material
    conditions:
      temper: as cast, not heat treated
      temperature: 200 °C
    method: Mechanical properties table of the Polish study (Table 3, Rm column)
    status: ground
    source: polsl-ev31a
    where: Table 3, 200 °C row, Rm column
  - benchmark: elongation_at_break
    label: Elongation A5, as cast, 200 °C (study sample, not heat treated)
    value: 31.2
    unit: '%'
    scope: material
    conditions:
      temper: as cast, not heat treated
      temperature: 200 °C
    method: Mechanical properties table of the Polish study (Table 3, A5 column)
    status: ground
    source: polsl-ev31a
    where: Table 3, 200 °C row, A5 column
  - benchmark: hardness_vickers
    label: Vickers hardness HV1, as cast (study sample)
    value: 47
    unit: HV1
    scope: material
    conditions:
      temper: as cast, not heat treated
      load: 1 kgf
    method: Vickers test on a ZWICK ZHV50 hardness tester, as printed in Table 3
    status: ground
    source: polsl-ev31a
    where: Table 3, 20 °C row, HV1 column
    note: Not in spores/property-canon.yaml; the snake_case name hardness_vickers is used.
  - benchmark: fatigue_strength
    label: Pull-pull fatigue strength, R = 0.1, 5 x 10^7 cycles
    value: 115
    value_high: 120
    bound: range
    unit: MPa
    scope: material
    conditions:
      load_ratio: 0.1
      cycles: 5 x 10^7
      test: pull-pull
    method: Fatigue properties section of the manufacturer datasheet
    status: ground
    source: luxfer-ds455
    where: Fatigue properties section, pull-pull R = 0.1 row
  - benchmark: fracture_toughness
    label: Fracture toughness, KIC
    value: 15.5
    unit: MPa m1/2
    scope: material
    conditions:
      temperature: not stated
    method: Other properties section of the manufacturer datasheet (printed as MPa m1/2)
    status: ground
    source: luxfer-ds455
    where: Ambient temperature mechanical properties section, Fracture toughness row
    note: Not in spores/property-canon.yaml; the snake_case name fracture_toughness is used.
  - benchmark: corrosion_rate
    label: Salt spray corrosion rate, ASTM B117, base metal (printed as upper limit)
    value: 1.14
    unit: mg/cm2/day
    scope: material
    conditions:
      test: ASTM B117 salt spray
      bound: upper limit, printed as less than 1.14
    method: Corrosion resistance section of the manufacturer datasheet
    status: ground
    source: luxfer-ds455
    where: Corrosion resistance section, ASTM B117 base metal row
    note: Not in spores/property-canon.yaml; the snake_case name corrosion_rate is used, as in the AZ31B profile.
  - benchmark: corrosion_rate
    label: Salt spray corrosion rate, ASTM B117, base metal (printed as upper limit)
    value: 90
    unit: mpy
    scope: material
    conditions:
      test: ASTM B117 salt spray
      bound: upper limit, printed as less than 90
    method: Corrosion resistance section of the manufacturer datasheet (printed as mpy)
    status: ground
    source: luxfer-ds455
    where: Corrosion resistance section, ASTM B117 base metal row (mpy)
    note: Not in spores/property-canon.yaml; the snake_case name corrosion_rate is used, as in the AZ31B profile.
corrosion:
  - environment: Salt spray, ASTM B117, base metal
    headline: The manufacturer's salt spray test gives an upper limit of 1.14 mg/cm2 per day, or 90 mpy.
    effect: The datasheet prints the base-metal salt spray rate as an upper limit, less than 1.14 mg/cm2/day and less than 90 mpy. It gives no chloride immersion rate for this alloy, and no sample count or test duration is printed.
    rating: low
    conditions:
      test: ASTM B117 salt spray
      basis: upper limit printed on the datasheet; the rating is set by the profile writer from the printed limit, not from a standard
    source: luxfer-ds455
    where: Corrosion resistance section, ASTM B117 base metal row
risks:
  hazards:
    - text: PubChem's aggregated GHS reports for magnesium metal (2,205 company reports from 27 ECHA notifications) give H228 (flammable solid) in 44.9% of reports, H250 (catches fire spontaneously if exposed to air) in 36.5%, H260 (in contact with water releases flammable gases which may ignite spontaneously) in 36.7%, H261 (in contact with water releases flammable gas) in 44.8% and H252 (self-heating in large quantities; may catch fire) in 18%. 18.4% of reports (405 of 2,205) say the element does not meet GHS criteria. These are element-level statements, not a classification of EV31A as supplied.
      ghs:
        - H228
        - H250
        - H260
        - H261
        - H252
      source: pubchem-mg
      where: Safety and Hazards, GHS Classification (CID 5462224), JSON view
  failure_risks:
    - mode: Low strength in the as-cast condition
      trigger: Use of the alloy without the T6 heat treatment
      consequence: The as-cast study sample gave 99 MPa 0.2% proof stress and 192 MPa tensile strength at 20 degC, below the norm values printed in that study (145 MPa and 248 MPa). The study says heat treatment is needed.
      severity: high
      source: polsl-ev31a
      where: Table 3 (20 degC row) and Section 4, conclusion 3
    - mode: Strength drop at 200 degC
      trigger: Service at the top of the rated range
      consequence: The as-cast study sample gave 69 MPa 0.2% proof stress and 168 MPa tensile strength at 200 degC, against 99 MPa and 192 MPa at 20 degC. The datasheet rates the alloy for use up to 200 degC.
      severity: moderate
      source: polsl-ev31a
      where: Table 3, 200 degC row
    - mode: Lower properties after welding
      trigger: Welding without a post-weld heat treatment
      consequence: The datasheet says castings should be heat treated after welding to obtain optimum properties.
      severity: moderate
      source: luxfer-ds455
      where: Weldability section
    - mode: Fire or flammable gas from magnesium metal
      trigger: Contact with water (H260, H261) or exposure to air of pyrophoric forms (H250)
      consequence: The GHS statements say the element can release flammable gas, catch fire spontaneously or be a flammable solid (element-level, not the alloy as supplied).
      severity: high
      source: pubchem-mg
      where: GHS Classification (CID 5462224)
  side_effects: []
  handling:
    - text: The GHS statements say that contact with water releases flammable gas (H261). Keep the metal dry and away from water.
      source: pubchem-mg
      where: GHS Classification, H261 and H260 statements (CID 5462224)
    - text: The datasheet says TIG welding is possible with a filler rod of similar composition, and that castings should be heat treated after welding.
      source: luxfer-ds455
      where: Weldability section
    - text: The datasheet says health and safety information is available for its products. This run did not open an SDS for EV31A, so read the supplier's SDS before cutting, grinding or welding.
      source: luxfer-ds455
      where: Footer note, Health and Safety information
  mitigations:
    - text: The datasheet gives a T6 treatment for castings, 8 hours at 520 degC, hot water quench at 60 to 80 degC or polymer quench, then 16 hours at 200 degC and air cool, to obtain optimum mechanical properties.
      source: luxfer-ds455
      where: Heat treatment section
uses:
  - application: mechanisms
    device: Transmission and gearbox housings
    example: The Polish study says EV31A is used for sports-car gearbox housings and helicopter gearbox housings. The Bell Helicopter abstract describes EV31A-T6 rotorcraft transmission housings.
    source: polsl-ev31a
    where: Section 1 (Introduction), paragraph on applications
  - application: structures
    device: Radar parts and torpedo parts (military)
    example: The Polish study names radar parts and torpedoes among the military uses of Elektron 21.
    source: polsl-ev31a
    where: Section 1 (Introduction), paragraph on applications
supply:
  - subject: Magnesium metal, world primary (smelter) production
    abundance: 'USGS: resources for magnesium range from large to virtually unlimited and are globally widespread; magnesium-bearing brines are estimated to be a resource in the billions of tons.'
    producers:
      - country: China
        share_percent: 87.7
        year: 2025
      - country: Russia
        share_percent: 5.5
        year: 2025
      - country: Brazil
        share_percent: 1.8
        year: 2025
      - country: Israel
        share_percent: 1.8
        year: 2025
      - country: Turkey
        share_percent: 1.4
        year: 2025
      - country: Kazakhstan
        share_percent: 1.2
        year: 2025
      - country: Iran
        share_percent: 0.5
        year: 2025
      - country: United States
        share_percent: 0
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (magnesium, used in metal alloys used by aerospace, automotive and electronics industries)
        listed: true
    recycling: 'USGS: secondary magnesium recovered from scrap was about 110 thousand metric tons in 2025 (estimate). The only US primary smelter, in Utah, stopped in 2022.'
    substitutes:
      - 'USGS: aluminum and zinc may substitute for magnesium in castings and wrought products. Magnesium''s light weight is an advantage over them in most applications; its high cost is a disadvantage.'
    source: usgs-mcs2026-magnesium-metal
    where: World Primary Production and Reserves table, smelter production 2025 (world total 1,100 thousand t, rounded; shares calculated by Space Mushroom over the listed 2025 values, sum 1,083 thousand t, as in the AZ31B profile). Recycling; Substitutes. Salient Statistics, secondary production 2025e (110).
  - subject: Magnesium metal imported to the United States, 2021 to 2024 (99.8 % purity)
    producers:
      - country: Israel
        share_percent: 47
      - country: Turkey
        share_percent: 31
      - country: Russia
        share_percent: 8
      - country: China
        share_percent: 6
    source: usgs-mcs2026-magnesium-metal
    where: Import Sources (2021 to 2024), magnesium metal (99.8% purity) row; the other 8% is not listed by country
documents:
  - title: 'Luxfer MEL Technologies datasheet DS 455: Elektron 21 (file DS-455-Elektron-21-0526, May 2026 revision)'
    type: datasheet
    url: https://www.luxfermeltechnologies.com/wp-content/uploads/2026/05/DS-455-Elektron-21-0526.pdf
    year: 2026
  - title: Kielbus A., Odlewniczy stop magnezu Elektron 21 - struktura i wlasciwosci w stanie lanym, Archives of Foundry 6(18), 2006 (Polish, English summary and table captions)
    type: paper
    url: https://delibra.bg.polsl.pl//Content/29050/BCPS_32307_-_Odlewniczy-stop-magn_0000.pdf
    year: 2006
  - title: Weihmuller L.W. (Bell Helicopter), Evaluation of EV31A-T6 Magnesium Casting Alloy for Rotorcraft Applications, AeroMat 2012, abstract HTA1.6
    type: paper
    url: https://asm.confex.com/asm/aero12/webprogram/Paper30854.html
    year: 2012
  - title: 'USGS Mineral Commodity Summaries 2026: Magnesium Metal'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-magnesium-metal.pdf
    year: 2026
  - title: 'USGS: About the 2025 List of Critical Minerals'
    type: report
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
  - title: 'PubChem: Magnesium, CID 5462224, Safety and Hazards, GHS Classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/5462224
gaps:
  - No immersion or chloride corrosion result for EV31A was read. The Springer paper (s40195-017-0548-9) returned a login redirect, and the MDPI papers (Metals 2026, 16(1), 4; Crystals 2022, stir-cast T4 and T6) returned 403. The Springer abstract's corrosion and 200 degC tensile figures were seen only in search snippets and are not used.
  - No T6 tensile values from a readable source beyond the datasheet typical and minimum rows. The datasheet's elevated temperature tensile curve (Figure 1) and creep curve (Figure 2) are graphs with no printed numbers read here, so they are not used.
  - 'MakeItFrom''s EV31A-T6 values (UTS 260 MPa, yield 170 MPa, elongation 3.5 %, thermal conductivity 86 W/m-K) were not read: the site returned 403. The values are not used.'
  - ASTM B80 and AMS 4429 are named by the datasheet, but the paywalled specification minimums were not read. Only the datasheet's minimum specification rows are used.
  - Compressive proof stress (168 MPa), compressive ultimate (367 MPa), shear ultimate (172 MPa) and notched impact at -35 degC (1.7 J) are printed on the datasheet but have no canonical name in spores/property-canon.yaml, so they are not recorded.
  - The Polish study sample is one as-cast lot from Magnesium Elektron. It is not a T6 result and is kept as a separate as-cast set.
  - Designation EV31A is linked to Elektron 21 by the Polish study's own text. UNS M12310 is printed on the datasheet against Elektron 21, not against EV31A.
  - 'Supply: the USGS figures cover magnesium metal in general, not EV31A. The 2025 producer shares are calculated from the listed values, because the text layout of the production table is mixed; the printed world total is 1,100 thousand t (rounded).'
  - Hazard data are element-level PubChem GHS statements for magnesium metal. No dust, fume or ignition temperature data for machining chips were found.
  - No licensed image of EV31A was found in this run, so the media list is empty.
  - 'Environments and stresses are empty: no source read in this run ties EV31A to a named space environment.'
media: []
sources:
  luxfer-ds455:
    title: 'Luxfer MEL Technologies datasheet DS 455: Elektron 21 (chemical composition, physical properties, design data, T6 heat treatment, corrosion, fatigue, low temperature, weldability)'
    url: https://www.luxfermeltechnologies.com/wp-content/uploads/2026/05/DS-455-Elektron-21-0526.pdf
    kind: datasheet
    license: Manufacturer datasheet, cited and not reproduced
  polsl-ev31a:
    title: Kielbus A., Odlewniczy stop magnezu Elektron 21 - struktura i wlasciwosci w stanie lanym, Archives of Foundry 6(18), 2006, pp. 173-178 (Silesian University of Technology)
    url: https://delibra.bg.polsl.pl//Content/29050/BCPS_32307_-_Odlewniczy-stop-magn_0000.pdf
    kind: paper
    license: Open-access repository copy, cited and not reproduced
  asm-aeromat-2012:
    title: Weihmuller L.W. (Bell Helicopter), Evaluation of EV31A-T6 Magnesium Casting Alloy for Rotorcraft Applications, AeroMat 2012, abstract HTA1.6
    url: https://asm.confex.com/asm/aero12/webprogram/Paper30854.html
    kind: paper
    license: Conference abstract page, cited and not reproduced
  usgs-mcs2026-magnesium-metal:
    title: 'USGS Mineral Commodity Summaries 2026: Magnesium Metal'
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-magnesium-metal.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS, final list)
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: web
    license: public domain (USGS)
  pubchem-mg:
    title: 'Magnesium, PubChem compound CID 5462224: Safety and Hazards, GHS Classification'
    id: PubChem CID 5462224; aggregated from ECHA C&L notifications
    url: https://pubchem.ncbi.nlm.nih.gov/compound/5462224
    kind: database
    license: PubChem (NCBI) public data
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 28
  unreachable: 5
  caveats: 4
  note: 'Written 2026-10-26 from pages read in this run: the Luxfer DS 455 PDF, the Polish study PDF, the ASM AeroMat abstract, the USGS MCS 2026 PDF, the USGS critical minerals page and the PubChem GHS JSON. Unreachable: Springer (login redirect), MDPI Metals and Crystals (403), MakeItFrom (403), Unibo (403). Caveats: as-cast values are a study sample, not T6; typical values are datasheet typical, not minimums; corrosion is an upper limit; hazard data are element-level.'
story:
  recipe:
    line: Cast magnesium alloy with neodymium and gadolinium as the main rare-earth additions, plus zinc and zirconium. The Luxfer datasheet gives the composition ranges and the T6 treatment for castings. The Polish study gives one sample composition from Magnesium Elektron, with rare earths totalling 4.2 wt%. The ASM abstract says it is a sand casting alloy.
    parts:
      - name: Magnesium
        symbol: Mg
        share_note: balance (the rest)
        role: The base metal and the balance of the alloy.
        source: luxfer-ds455
        where: Chemical composition table, Magnesium row (balance)
      - name: Neodymium
        symbol: Nd
        share_percent: 2.6
        share_high: 3.1
        role: Main rare-earth addition, raises strength at temperature.
        source: luxfer-ds455
        where: Chemical composition table, Neodymium row
      - name: Gadolinium
        symbol: Gd
        share_percent: 1
        share_high: 1.7
        role: Rare-earth addition that replaces the more costly yttrium, according to the Polish study.
        source: polsl-ev31a
        where: Introduction, paragraph on Elektron 21 (replaces the costly yttrium); composition from Chemical composition table of luxfer-ds455
      - name: Zinc
        symbol: Zn
        share_percent: 0.2
        share_high: 0.5
        role: Minor addition.
        source: luxfer-ds455
        where: Chemical composition table, Zinc row
      - name: Zirconium
        symbol: Zr
        share_note: saturated (printed as Saturated)
        role: Grain refiner.
        source: luxfer-ds455
        where: Chemical composition table, Zirconium row
  risk_groups:
    - title: For people
      lead: The only hazard data opened is PubChem's GHS data for magnesium metal. It is element-level, not a classification of EV31A as supplied.
      gap: No safety data sheet for the alloy was opened, and no dust or fume data for machining or welding was found.
      points:
        - label: Fire statements
          line: Magnesium metal is listed as a flammable solid (H228), as catching fire spontaneously if exposed to air (H250), and as releasing flammable gases on contact with water (H260, H261). Self-heating is also reported (H252).
    - title: If it fails
      lead: The failure routes come from the Polish as-cast test, the datasheet's welding note and the GHS statements.
      points:
        - label: As cast
          line: The as-cast sample reached 99 MPa 0.2% proof stress and 192 MPa tensile strength at 20 degC, below the norm values printed in that study.
        - label: Heat
          line: At 200 degC the as-cast sample reached 69 MPa proof stress and 168 MPa tensile strength.
        - label: Welds
          line: The datasheet says castings should be heat treated after welding to obtain optimum properties.
    - title: Handling and storage
      points:
        - label: Water
          line: Contact with water releases flammable gas (H261), so keep the metal dry.
        - label: Welding
          line: Weld by TIG with a similar filler rod, then heat treat the casting.
  why: EV31A is a casting alloy developed by Magnesium Elektron as a more producible alternative to the yttrium-bearing WE series of alloys. The ASM abstract says it gives greater strength at temperature and corrosion resistance than sand casting alloys such as ZE41A. The datasheet calls it a high strength, fully heat treatable alloy for use up to 200 degC, aimed at motorsport and aerospace. USGS lists magnesium on the 2025 critical minerals list.
  uses:
    - where: Transmission and gearbox housings
      line: The Polish study names sports-car gearbox housings and helicopter gearbox housings. The Bell Helicopter abstract describes EV31A-T6 rotorcraft transmission housings.
    - where: Radar and torpedo parts
      line: The Polish study names radar parts and torpedoes among military uses.
  can_do:
    - label: Weight
      value: 1.82 g/cm3
      line: The datasheet gives specific gravity 1.82, read here as density.
      benchmark: density
    - label: Strength after T6, typical
      value: 280 MPa tensile
      line: The datasheet gives typical ambient tensile strength of 280 MPa, with 170 MPa 0.2% proof stress and 5 % elongation. The row does not name the temper, but the datasheet heat treatment for castings is T6.
      benchmark: ultimate_tensile_strength
    - label: Heat conduction
      value: 116 W/(m·K)
      line: The datasheet gives thermal conductivity of 116 W/(m·K) at a temperature the datasheet does not state.
      benchmark: thermal_conductivity
    - label: Thermal expansion
      value: 26.3 ppm/K
      line: The datasheet gives a coefficient of thermal expansion of 26.3 ppm/K, with no temperature range printed.
      benchmark: cte
    - label: Corrosion in salt spray
      value: 1.14 mg/cm2/day
      line: The datasheet gives an ASTM B117 base-metal upper limit of less than 1.14 mg/cm2 per day (less than 90 mpy).
      benchmark: corrosion_rate
  compare: The USGS says aluminum and zinc can substitute for magnesium in castings and wrought products, and that magnesium's light weight is an advantage over them in most applications, although its high cost is a disadvantage. This profile holds no strength-per-mass figures for aluminum or zinc, so it does not rank EV31A against them. The Polish study's as-cast values are below the datasheet minimums, so only the T6 datasheet rows are used for comparison.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Thermal conductivity
      benchmark: thermal_conductivity
    - label: Thermal expansion
      benchmark: cte
  handling:
    - Keep the metal dry. The GHS statements say contact with water releases flammable gas (H261 in 44.8% of reports).
    - Weld by TIG with a similar filler rod, and heat treat the casting after welding, as the datasheet says.
    - Read the supplier's safety data sheet before cutting, grinding or welding. This run did not open one for EV31A.
    - Salt spray data are upper limits only. No chloride immersion rate for this alloy was read, so plan protection by test rather than by this profile.
  good_for:
    - Castings for transmission and gearbox housings that must hold strength up to 200 degC. The Polish study and the Bell Helicopter abstract name these uses.
    - Parts where a heat treatment after casting is acceptable, since the datasheet gives a T6 route for optimum properties.
    - Parts that are welded by TIG with heat treatment after welding, as the datasheet describes.
  watch_out:
    - As-cast strength. The as-cast study sample was below the norms, so the T6 treatment is not optional.
    - Temperature. The as-cast sample lost much of its strength at 200 degC (168 MPa tensile against 192 MPa at 20 degC).
    - Corrosion. The datasheet's salt spray rate is an upper limit. No immersion data for this alloy were read.
    - Fire. The GHS statements for magnesium metal include flammable solid (H228) and catches fire spontaneously if exposed to air (H250).
  verdict: EV31A is a heat-treatable magnesium casting alloy rated for use up to 200 degC, with a manufacturer datasheet that gives T6 and welding routes. The as-cast values from the Polish study fall below the norms, so treatment is needed. Corrosion data are limited to a salt spray upper limit.