spore: profile
id: aluminium-silicon-ce7
spore_version: '0.2'
family: aluminium-alloys
name: Osprey CE7 silicon-aluminium alloy
abbreviation: CE7
role: controlled-expansion packaging alloy (Si-30%Al, Osprey CE7F)
category: metals
type: aluminium
summary: CE7 is an Osprey silicon-aluminium alloy (Si-30%Al, about 70 % Si and 30 % Al by weight) with interwoven silicon and aluminium phases and a grain size of about 10 µm (arXiv 2018). Its room-temperature expansion is 7.2 ppm/°C on the maker's current listing, and 7.5 ppm/°C from 25 °C to 500 °C in a 2003 article, close to gallium arsenide and alumina. The 2018 arXiv paper measured superconductivity at 1.190 K and poor heat conduction at 300 mK. No flight or spacecraft record was found in the sources read.
best_for: Machined housings, carriers and interface plates for silicon and gallium arsenide microwave parts, and for cryogenic millimetre-wave detectors, where the expansion must stay close to that of the part
weakest_at: Brittleness (yield and ultimate tensile strength are nearly the same) and poor thermal conduction at cryogenic temperatures unless the parts are gold plated
identity:
  formula: Si-Al alloy, about 70 % Si and 30 % Al by weight (printed as Si-30%Al)
  cas: ''
  source: ospreyatomiqs-materials
  where: Controlled expansion alloys list, entry Osprey CE7F, printed as Si-30%Al
  designations:
    - system: Trade name
      code: CE7F
      note: Osprey CE7F, controlled expansion aluminium-silicon alloy
      source: ospreyatomiqs-materials
      where: Controlled expansion alloys list, entry Osprey CE7F
    - system: Trade name
      code: CE7
      note: older name, printed without the F suffix
      source: mwj-osprey-2003
      where: Table 1 Key Properties, column header CE7
tags:
  environments: []
  stresses:
    - extreme-cold
  applications:
    - electronics-and-chips
    - optics-and-cameras
    - thermal-control
properties:
  - benchmark: density
    label: Density, CE7 (arXiv Table 1)
    value: 2.43
    unit: g/cm3
    scope: material
    conditions:
      temperature: not stated in table
      form: not stated
    method: Value printed in Table 1 of the 2018 arXiv paper, column CE7. The paper credits its mechanical values to Sandvik Osprey measurements at room temperature.
    status: ground
    source: arxiv-ali-2018
    where: Table 1, row Density (g/cm3), column CE7
  - benchmark: density
    label: Density, CE7F (Osprey current listing)
    value: 2.43
    unit: g/cc
    scope: material
    conditions:
      grade: Osprey CE7F, Si-30%Al
      temperature: not stated
    method: Value printed on the maker's current materials listing
    status: ground
    source: ospreyatomiqs-materials
    where: Controlled expansion alloys list, entry Osprey CE7F (printed as a density of 2.43 g/cc)
  - benchmark: cte
    label: Coefficient of thermal expansion at room temperature (Osprey current listing)
    value: 7.2
    unit: ppm/°C
    scope: material
    conditions:
      grade: Osprey CE7F, Si-30%Al
      temperature: room temperature (as printed)
    method: Value printed on the maker's current materials listing
    status: ground
    source: ospreyatomiqs-materials
    where: Controlled expansion alloys list, entry Osprey CE7F (printed as a room-temperature expansion of 7.2 ppm/°C)
  - benchmark: cte
    label: Coefficient of thermal expansion, 25 °C to 500 °C (Microwave Journal 2003)
    value: 7.5
    unit: ppm/°C
    scope: material
    conditions:
      temperature_range: 25 °C to 500 °C
      grade: CE7, Si-30% Al
    method: Value printed in the property table of a 2003 Osprey Metals article in Microwave Journal
    status: ground
    source: mwj-osprey-2003
    where: Table 1 Key Properties, row Coefficient of thermal expansion 25°C - 500°C, column CE7
  - benchmark: cte
    label: Coefficient of thermal expansion, 25 °C to 500 °C (LookPolymers record)
    value: 7.7
    unit: µm/m-°C
    scope: material
    conditions:
      temperature_range: 25.0 - 500 °C
      grade: Si-30%Al
    method: Value printed in the Thermal Properties table of a MatWeb-format record, information provided by Osprey Metals
    status: ground
    source: lookpolymers-ce7
    where: Thermal Properties table, row CTE linear, @Temperature 25.0 - 500 °C
  - benchmark: elastic_modulus
    label: Young's modulus, CE7 (arXiv Table 1)
    value: 129.2
    unit: GPa
    scope: material
    conditions:
      temperature: not stated (mechanical values measured at room temperature by Sandvik Osprey, per the paper)
    method: Value printed in Table 1 of the 2018 arXiv paper
    status: ground
    source: arxiv-ali-2018
    where: Table 1, row Young's modulus (GPa), column CE7
  - benchmark: elastic_modulus
    label: Modulus of elasticity (Microwave Journal 2003)
    value: 120
    unit: GPa
    scope: material
    conditions:
      grade: CE7, Si-30% Al
      temperature: not stated
    method: Value printed in the property table of a 2003 Osprey Metals article
    status: ground
    source: mwj-osprey-2003
    where: Table 1 Key Properties, row Youngs Modulus (GPa), column CE7
  - benchmark: elastic_modulus
    label: Modulus of elasticity (LookPolymers record)
    value: 125
    unit: GPa
    scope: material
    conditions:
      grade: Si-30%Al
      temperature: not stated
    method: Value printed in the Mechanical Properties table of a MatWeb-format record, information provided by Osprey Metals
    status: ground
    source: lookpolymers-ce7
    where: Mechanical Properties table, row Modulus of Elasticity, metric 125 GPa
  - benchmark: shear_modulus
    label: Rigidity (shear) modulus, CE7 (arXiv Table 1)
    value: 51.6
    unit: GPa
    scope: material
    conditions:
      temperature: not stated in table
    method: Value printed in Table 1 of the 2018 arXiv paper
    status: ground
    source: arxiv-ali-2018
    where: Table 1, row Rigidity modulus (GPa), column CE7
  - benchmark: shear_modulus
    label: Shear modulus (LookPolymers record)
    value: 50
    unit: GPa
    scope: material
    conditions:
      grade: Si-30%Al
      temperature: not stated
    method: Printed in the record's Shear Modulus row, which is marked Calculated in the source
    status: calculated
    source: lookpolymers-ce7
    where: Mechanical Properties table, row Shear Modulus, metric 50.0 GPa (marked Calculated)
  - benchmark: poissons_ratio
    label: Poisson's ratio, CE7 (arXiv Table 1)
    value: 0.26
    unit: '-'
    scope: material
    conditions:
      temperature: not stated in table
    method: Value printed in Table 1 of the 2018 arXiv paper
    status: ground
    source: arxiv-ali-2018
    where: Table 1, row Poisson's ratio, column CE7
  - benchmark: poissons_ratio
    label: Poisson's ratio (LookPolymers record)
    value: 0.25
    unit: '-'
    scope: material
    conditions:
      grade: Si-30%Al
      temperature: not stated
    method: Value printed in the Mechanical Properties table of a MatWeb-format record
    status: ground
    source: lookpolymers-ce7
    where: Mechanical Properties table, row Poissons Ratio, value 0.25
  - benchmark: yield_strength
    label: Yield strength, CE7 (arXiv Table 1)
    value: 110
    unit: MPa
    scope: material
    conditions:
      test: room temperature, mechanical measurement by Sandvik Osprey (per the paper)
      form: not stated
    method: Value printed in Table 1 of the 2018 arXiv paper. The table lists yield above the ultimate strength of about 100 MPa, and the paper describes the two as similar.
    status: ground
    source: arxiv-ali-2018
    where: Table 1, row Yield strength (MPa), column CE7
  - benchmark: ultimate_tensile_strength
    label: Ultimate tensile strength, CE7 (arXiv Table 1)
    value: 100
    unit: MPa
    scope: material
    conditions:
      printed: approximately 100 (printed as ∼100)
      test: room temperature, mechanical measurement by Sandvik Osprey (per the paper)
    method: Value printed as approximately 100 in Table 1 of the 2018 arXiv paper
    status: ground
    source: arxiv-ali-2018
    where: Table 1, row Ultimate tensile strength (MPa), column CE7 (printed as ∼100)
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, ultimate (LookPolymers record)
    value: 100
    unit: MPa
    scope: material
    conditions:
      grade: Si-30%Al
      temperature: not stated
    method: Value printed in the Mechanical Properties table of a MatWeb-format record
    status: ground
    source: lookpolymers-ce7
    where: Mechanical Properties table, row Tensile Strength Ultimate, metric 100 MPa
  - benchmark: flexural_strength
    label: Bend strength, three point (Microwave Journal 2003)
    value: 150
    unit: MPa
    scope: material
    conditions:
      test: three point bend
      grade: CE7, Si-30% Al
    method: Value printed in the property table of a 2003 Osprey Metals article
    status: ground
    source: mwj-osprey-2003
    where: Table 1 Key Properties, row Bend Strength (three point) (MPa), column CE7
  - benchmark: flexural_strength
    label: Flexural strength (LookPolymers record)
    value: 143
    unit: MPa
    scope: material
    conditions:
      grade: Si-30%Al
      test: not stated
    method: Value printed in the Mechanical Properties table of a MatWeb-format record
    status: ground
    source: lookpolymers-ce7
    where: Mechanical Properties table, row Flexural Strength, metric 143 MPa
  - benchmark: superconducting_critical_temperature
    label: Superconducting critical temperature, CE7 (arXiv)
    value: 1.19
    uncertainty: ± .005 K (printed)
    unit: K
    scope: material
    conditions:
      definition: point where the resistivity is half of the normal value
      apparatus: four-lead resistance in an ADR cryostat
    method: Four-lead resistance measurement, 25 sweeps averaged, in the 2018 arXiv paper
    status: ground
    source: arxiv-ali-2018
    where: 'Section 2.1 Superconductivity, text: Tc = 1.190 ± .005 K'
  - benchmark: electrical_resistivity
    label: Electrical resistivity above about 1.2 K (arXiv)
    value: 0.5
    unit: µΩ·m
    scope: material
    conditions:
      temperature: above about 1.2 K (text); 1.5 K (Table 1)
      uncertainty_in_source: ± .03 (text)
    method: Four-lead resistance measurement in the 2018 arXiv paper
    status: ground
    source: arxiv-ali-2018
    where: Section 2.1 text (0.50 ± .03 µΩ·m) and Table 1, row Resistivity 1.5 K (µΩ·m)
  - benchmark: thermal_conductivity
    label: Thermal conductivity of bare CE7 at 300 mK (arXiv)
    value: 0.005
    uncertainty: ± 0.001
    unit: W/m·K
    scope: material
    conditions:
      temperature: 300 mK
      finish: bare, not plated
      sample: rectangular bar about 10 cm x 1 cm x 1 cm
    method: Heater-and-gradient measurement on a bar on an ADR cold stage, in the 2018 arXiv paper
    status: ground
    source: arxiv-ali-2018
    where: 'Section 2.3 Thermal Conductivity, text: approximately 0.005±0.001 (W/m · K) at 300 mK'
  - benchmark: thermal_conductivity
    label: Thermal conductivity of gold-plated CE7 at 300 mK (arXiv)
    value: 0.02
    uncertainty: ± 0.005
    unit: W/m·K
    scope: material
    conditions:
      temperature: 300 mK
      finish: 7 µm electroless nickel, then 3.8 µm soft gold
    method: Same bar type as the bare sample, electroplated with gold, in the 2018 arXiv paper
    status: ground
    source: arxiv-ali-2018
    where: 'Section 2.3 Thermal Conductivity, text: 0.02±0.005 (W/m · K) at 300 mK for Au-plated CE7; plating in Section 3.2'
  - benchmark: thermal_conductivity
    label: Thermal conductivity of gold-plated CE7 at 100 mK (arXiv)
    value: 0.006
    uncertainty: ± 0.002
    unit: W/m·K
    scope: material
    conditions:
      temperature: 100 mK
      finish: 7 µm electroless nickel, then 3.8 µm soft gold
    method: Same gold-plated bar as the 300 mK row, in the 2018 arXiv paper
    status: ground
    source: arxiv-ali-2018
    where: 'Section 2.3 Thermal Conductivity, text: 0.006±0.002 (W/m · K) at 100 mK for Au-plated CE7'
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 25 °C (Microwave Journal 2003)
    value: 120
    unit: W/mK
    scope: material
    conditions:
      temperature: 25 °C
      grade: CE7, Si-30% Al
    method: Value printed in the property table of a 2003 Osprey Metals article
    status: ground
    source: mwj-osprey-2003
    where: Table 1 Key Properties, row Thermal conductivity at 25°C (W/mK), column CE7
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 25.0 °C (LookPolymers record)
    value: 120
    unit: W/m-K
    scope: material
    conditions:
      temperature: 25.0 °C
      grade: Si-30%Al
    method: Value printed in the Thermal Properties table of a MatWeb-format record
    status: ground
    source: lookpolymers-ce7
    where: Thermal Properties table, row Thermal Conductivity, @Temperature 25.0 °C, value 120 W/m-K
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 200 °C (LookPolymers record)
    value: 100
    unit: W/m-K
    scope: material
    conditions:
      temperature: 200 °C
      grade: Si-30%Al
    method: Value printed in the Thermal Properties table of a MatWeb-format record
    status: ground
    source: lookpolymers-ce7
    where: Thermal Properties table, row Thermal Conductivity, @Temperature 200 °C, value 100 W/m-K
  - benchmark: specific_heat
    label: Specific heat capacity (LookPolymers record)
    value: 0.75
    unit: J/g-°C
    scope: material
    conditions:
      temperature: not stated in record
      grade: Si-30%Al
    method: Value printed in the Specific Heat Capacity row of a MatWeb-format record
    status: ground
    source: lookpolymers-ce7
    where: Thermal Properties table, row Specific Heat Capacity, value 0.750 J/g-°C
  - benchmark: linear_contraction_300K_to_4K
    label: Linear thermal contraction, 300 K to 4 K (upper limit, arXiv)
    value: 0.001
    bound: upper
    unit: '-'
    scope: material
    conditions:
      range: 300 K down to 4 K
      quantity: fractional linear contraction (dimensionless)
    method: Strain gauge calibrated and epoxied to a 6.35 cm square CE7 sample, cooled to 4 K, in the 2018 arXiv paper
    status: ground
    source: arxiv-ali-2018
    where: 'Section 2.2 Thermal Contraction, text: the fractional linear contraction was constrained to be less than 0.001'
corrosion: []
risks:
  hazards:
    - text: Osprey says the CE alloys are environmentally friendly, safe to handle and use, and present no disposal problems. This is the maker's own statement. No safety data sheet for CE7 was read in this run.
      ghs: []
      source: mwj-osprey-2003
      where: Main Attributes section, paragraph on environmental and handling properties
    - text: PubChem's aggregated ECHA C&L record for silicon (CID 5461123) says it does not meet GHS hazard criteria for 96.3% (3142 of 3263) of all reports. 11 notifications from 121 of 3263 reports give H228 (flammable solid) and H320 (causes eye irritation); the record does not say which physical form each notification covers. These codes describe the element, not the CE7 alloy.
      ghs:
        - H228
        - H320
      source: pubchem-silicon
      where: Safety and Hazards, GHS Classification (aggregated ECHA C&L notification summary)
    - text: PubChem's aggregated ECHA C&L record for aluminum (CID 5359268) covers 4079 reports. Of these, 338 (8.3%) say the chemical does not meet GHS hazard criteria. Among reports that give codes, H261 (in contact with water releases flammable gas) is given in 90.8%, H228 (flammable solid) in 60.6% and H250 (catches fire spontaneously if exposed to air) in 34.2%. Single notifications also list H370 and H372 (damage to organs). The record does not separate powder from bulk metal, so these codes are not read as the CE7 alloy's own.
      ghs:
        - H261
        - H228
        - H250
      source: pubchem-aluminum
      where: Safety and Hazards, GHS Classification (aggregated ECHA C&L summary, percentages in parentheses)
  failure_risks:
    - mode: Brittle fracture with little plastic deformation
      consequence: The paper reads the similar yield and ultimate strengths of CE7 as a sign of brittleness with minimal plastic deformation, a property inherited from silicon.
      source: arxiv-ali-2018
      where: Table 1 caption and the text after Table 1
    - mode: Fracture at grain boundaries during machining
      consequence: Structures near the grain size are typically difficult to machine because fractures occur at grain boundaries. Parts were still produced to a surface finish better than 0.4 µm.
      source: arxiv-ali-2018
      where: Section 3.4 Fabrication
  side_effects: []
  handling:
    - text: Machine with carbide or polycrystalline diamond tools to a fine finish of 0.5 µm. Recesses, pedestals, holes, slots and tabs machine readily.
      source: mwj-osprey-2003
      where: Section Applications, paragraph on machining
    - text: In the CE7 grade, EDM tapping or threaded inserts may be desirable for tapped holes.
      source: mwj-osprey-2003
      where: Section on machining, after Table 1
    - text: 'Gold-plate parts for cryogenic thermal contact: the 2018 team used 7 µm electroless nickel, then 3.8 µm soft gold, because bare CE7 conducts heat poorly.'
      source: arxiv-ali-2018
      where: Section 3.2 Thermal Conductivity and Gold Plating
  mitigations:
    - text: Gold plating raised the measured thermal conductivity at 300 mK from 0.005 to 0.02 W/m·K in the 2018 tests.
      source: arxiv-ali-2018
      where: Section 2.3 text, bare and Au-plated values at 300 mK
uses:
  - application: electronics-and-chips
    device: RF and microwave flanges, light-weight carriers and packages
    example: Osprey lists CE7 for RF/microwave flanges, light-weight carriers and packages, for its expansion match to circuit boards and components.
    source: mwj-osprey-2003
    where: Table 2 Properties Tailored to Applications, first row
  - application: optics-and-cameras
    device: Millimetre-wave detector interface plates and feedhorn arrays for the 93 GHz CLASS telescopes
    example: CE7 baseplates are deployed in the 93 GHz polarimetric focal planes of the Cosmology Large Angular Scale Surveyor (CLASS), and a 91-element CE7 feedhorn array was machined.
    source: arxiv-ali-2018
    where: Abstract; Section 3 text on CLASS interface plates; Figure 5 caption (91-element CE7 feedhorn array)
  - application: thermal-control
    device: Heat sinks for power modules and discrete devices
    example: Osprey names heat sinks for power modules and discrete devices as an important application area for its CE alloys.
    source: mwj-osprey-2003
    where: Applications section, paragraph beginning Another important application area
supply:
  - subject: Silicon (the main element of CE7), read from silicon materials production
    abundance: World and domestic resources for making silicon metal and alloys are abundant (USGS).
    producers:
      - country: China
        share_percent: 80
        year: 2025
    critical_lists:
      - list: USGS 2025 Final List of Critical Minerals (silicon added, Federal Register 7 Nov 2025)
        listed: true
    substitutes:
      - Gallium arsenide and germanium are the principal substitutes for silicon in semiconductor and infrared applications (USGS).
    source: usgs-mcs2026-silicon
    where: 'Events, Trends, and Issues: China accounted for almost 80% of total global estimated production of silicon materials in 2025 (printed as almost 80%); Critical minerals paragraph; World Resources and Substitutes sections'
  - subject: Aluminium (about 30 % of CE7 by weight), read from the USGS aluminum summary
    abundance: USGS 2026 prints world smelter production of 74,000 thousand metric tons in 2025e (rounded), of which China 45,000 thousand metric tons. In 2025 about 56% of aluminum recovered from purchased US scrap came from new scrap and 44% from old scrap.
    producers: []
    critical_lists: []
    substitutes: []
    source: usgs-mcs2026-aluminum
    where: World Smelter Production and Capacity table, column Smelter production 2025e (China and World total, rounded); Recycling paragraph
documents:
  - title: 'Ali et al. 2018, SiAl Alloy Feedhorn Arrays: Material Properties, Feedhorn Design, and Astrophysical Applications (arXiv:1807.03398)'
    type: paper
    url: https://arxiv.org/pdf/1807.03398
    year: 2018
  - title: Osprey Metals, Controlled Expansion Alloys for High Reliability Packaging Solutions (Microwave Journal, article dated January 1, 2003)
    type: datasheet
    url: https://www.microwavejournal.com/articles/3571-controlled-expansion-alloys-for-high-reliability-packaging-solutions
    year: 2003
  - title: Osprey Atomiqs materials list, controlled expansion alloys (entry Osprey CE7F)
    type: datasheet
    url: https://www.ospreyatomiqs.com/materials
  - title: 'LookPolymers record: Osprey Metals CE7 Al-Si Controlled Expansion Alloy (MatWeb-format, information provided by Osprey Metals)'
    type: datasheet
    url: https://www.lookpolymers.com/polymer_Osprey-Metals-CE7-Al-Si-Controlled-Expansion-Alloy.php
  - title: 'USGS Mineral Commodity Summaries 2026: Silicon'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.pdf
    year: 2026
  - title: 'PubChem compound record: Silicon (CID 5461123), GHS Classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Silicon
  - title: 'PubChem compound record: Aluminum (CID 5359268), GHS Classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Aluminum
  - title: 'USGS Mineral Commodity Summaries 2026: Aluminum'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
    year: 2026
gaps:
  - No corrosion, humidity, salt-spray or ageing test result for CE7 was found in any source read. The corrosion list is empty.
  - No flight, spacecraft or launch record for CE7 was found. The 2018 paper describes ground cryogenic telescopes (CLASS) only.
  - No CE7 safety data sheet was read. The maker's safe-handling claim is kept, and PubChem GHS records for the elements silicon and aluminum are added as hazard entries. Those records describe the elements and their forms, not the CE7 alloy.
  - The USGS 2026 aluminum summary, read in this run, prints no critical-minerals listing, so no critical list is recorded for aluminium.
  - The USGS 2026 aluminum summary prints no producer shares as percentages, so no aluminium producer shares are recorded. The printed 2025e tonnages are kept in the supply abundance text.
  - No images, drawings or other media were recorded for CE7 in this run.
  - The 2003 Microwave Journal table prints a CE7 density of 2.40 with the unit printed as g/cm with a superscript 2 (g/cm2). The unit is not recorded because it is printed in a non-standard form, so the density value is left out.
  - The 2018 paper's Table 1 prints the thermal conductivity of CE7 at 300 mK as 0.02, while its text gives 0.005 for bare CE7. Both text values are recorded; the table row is not recorded separately because it matches the gold-plated value.
  - The 2018 paper's Table 1 prints the contraction from 293 K to 1 K as <10 with a x10^4 factor. Exponent-style values are not recorded, so this row is left out. The paper's predicted value of about .0012 is also left out.
  - 'Young''s modulus differs by source: 129.2 GPa (arXiv Table 1), 125 GPa (LookPolymers) and 120 GPa (Microwave Journal 2003). All three are kept as separate rows, not averaged.'
  - 'The shear modulus differs: 51.6 GPa (arXiv Table 1) and 50.0 GPa (LookPolymers, marked Calculated). Both are kept.'
  - The room-temperature expansion (7.2 ppm/°C, Osprey listing) and the 25 °C to 500 °C expansion (7.5 ppm/°C, Microwave Journal; 7.70 µm/m-°C, LookPolymers) are different tests. All are kept side by side.
  - The ultimate tensile strength (about 100 MPa) is printed lower than the yield strength (110 MPa) in the arXiv Table 1. Both are kept as printed, and the paper calls the two similar.
  - 'Density: 2.43 g/cm3 (arXiv Table 1) and 2.43 g/cc (Osprey listing) agree. The CE7 composition basis is given as wt % in the 2003 article only.'
  - The meaning of the F suffix in CE7F is not printed in any source read. The older name CE7 is used in the 2003 article and the 2018 paper.
  - The LookPolymers record prints a Vickers hardness of 255 with no unit, so it is not recorded.
  - No tempers, heat treatments or form (cast, sprayed or machined) are printed for the mechanical values. The paper measured its sample, and the form is not stated.
  - The superconducting critical temperature and linear contraction benchmarks are not in property-canon.yaml. Short snake_case names are used for them.
  - Aluminium supply is covered by the aluminium-alloy profiles and is not repeated here. The supply entry covers silicon only, using USGS 2026 printed figures.
  - No space-environment data (outgassing, radiation or thermal cycling in orbit) were found in the sources read.
sources:
  arxiv-ali-2018:
    title: 'Ali et al. 2018, SiAl Alloy Feedhorn Arrays: Material Properties, Feedhorn Design, and Astrophysical Applications'
    id: arXiv:1807.03398
    url: https://arxiv.org/pdf/1807.03398
    year: 2018
    kind: paper
    license: arXiv preprint (cited, not reproduced)
  mwj-osprey-2003:
    title: Osprey Metals, Controlled Expansion Alloys for High Reliability Packaging Solutions (Microwave Journal, article dated January 1, 2003)
    url: https://www.microwavejournal.com/articles/3571-controlled-expansion-alloys-for-high-reliability-packaging-solutions
    year: 2003
    kind: web
    license: Trade journal article (cited, not reproduced)
  ospreyatomiqs-materials:
    title: Osprey Atomiqs materials list, controlled expansion alloys (entry Osprey CE7F)
    url: https://www.ospreyatomiqs.com/materials
    kind: datasheet
    license: Manufacturer materials listing (cited, not reproduced)
  lookpolymers-ce7:
    title: 'LookPolymers record: Osprey Metals CE7 Al-Si Controlled Expansion Alloy (MatWeb-format, information provided by Osprey Metals)'
    url: https://www.lookpolymers.com/polymer_Osprey-Metals-CE7-Al-Si-Controlled-Expansion-Alloy.php
    kind: datasheet
    license: Supplier record (cited, not reproduced)
  usgs-mcs2026-silicon:
    title: 'USGS Mineral Commodity Summaries 2026: Silicon'
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  pubchem-silicon:
    title: 'PubChem compound record: Silicon (CID 5461123), Safety and Hazards, GHS Classification'
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Silicon
    kind: database
    license: Public database record (cited, not reproduced)
  pubchem-aluminum:
    title: 'PubChem compound record: Aluminum (CID 5359268), Safety and Hazards, GHS Classification'
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Aluminum
    kind: database
    license: Public database record (cited, not reproduced)
  usgs-mcs2026-aluminum:
    title: 'USGS 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)
license: CC-BY-4.0
updated: '2026-11-02'
review:
  status: draft
  method: assistant
  checked_values: 27
  unreachable: 0
  caveats: 6
  note: Values were read by an AI assistant on 2026-11-01 from the pages named in each entry. Sources disagree on density, Young's modulus, shear modulus, thermal expansion and thermal conductivity; each value is kept with its own source. The CE7 mechanical values come from a 2018 paper that credits Sandvik Osprey measurements. No flight, corrosion or SDS data were found.
story:
  why: 'Semiconductors and ceramic circuit boards are relatively fragile, so a package material whose expansion is close to theirs keeps them in slight compression over the whole service range (Microwave Journal, 2003). CE7 is Osprey''s silicon-aluminium alloy built for that job. Its expansion of 7.5 ppm/°C from 25 °C to 500 °C is close to that of gallium arsenide and alumina, as the 2003 article states. The 2018 arXiv paper added cryogenic tests: CE7 superconducts at 1.190 K and conducts heat poorly at 300 mK.'
  uses:
    - where: RF and microwave packages
      line: Osprey lists CE7 for RF/microwave flanges, light-weight carriers and packages, because its expansion matches circuit boards and components (Microwave Journal, 2003).
    - where: Cryogenic millimetre-wave detectors
      line: CE7 baseplates are deployed in the 93 GHz polarimetric focal planes of CLASS, and a 91-element CE7 feedhorn array was machined (arXiv 2018).
  can_do:
    - label: Match thermal expansion
      line: Osprey gives 7.5 ppm/°C from 25 °C to 500 °C in its 2003 article, and 7.2 ppm/°C at room temperature on its current listing.
      value: 7.5 ppm/°C (2003); 7.2 ppm/°C (current listing)
      benchmark: cte
    - label: Low density
      line: Osprey's current listing and the 2018 arXiv paper both give a density of 2.43 g/cc.
      value: 2.43 g/cc
      benchmark: density
    - label: Superconduct at low temperature
      line: The 2018 arXiv paper measured a critical temperature of 1.190 K, with an uncertainty of ± .005 K as printed.
      value: 1.190 K
      benchmark: superconducting_critical_temperature
    - label: Fine machined finish
      line: Osprey gives a finish of 0.5 µm with carbide or polycrystalline diamond tools.
      value: 0.5 µm
  compare: The sources read do not compare CE7 numerically with other grades in this collection. The 2003 Microwave Journal article ranks CE7 among its CE alloys by expansion, and says its expansion matches gallium arsenide and alumina fairly closely. The 2018 arXiv paper compares CE7 with silicon, aluminium, copper and alumina in its Table 1, but no values for those other materials are recorded here, so no numerical comparison is made.
  compare_rows:
    - label: Thermal expansion (CTE)
      benchmark: cte
    - label: Density
      benchmark: density
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Machine with carbide or polycrystalline diamond tools to a finish of 0.5 µm (Microwave Journal, 2003).
    - Use EDM tapping or threaded inserts for tapped holes in CE7, as the 2003 article suggests.
    - Gold-plate parts for cryogenic thermal contact with 7 µm electroless nickel and 3.8 µm soft gold (arXiv 2018).
  good_for:
    - Machined housings, flanges and carriers for silicon and gallium arsenide microwave parts that need an expansion close to the part (Microwave Journal, 2003).
    - Cryogenic millimetre-wave detector interface plates and feedhorn arrays, as used in the 93 GHz CLASS focal planes (arXiv 2018).
  watch_out:
    - 'Brittle: yield (110 MPa) and ultimate tensile strength (about 100 MPa) are nearly the same in the 2018 table.'
    - 'Poor thermal conduction at cryogenic temperatures: 0.005 W/m·K when bare at 300 mK, so the 2018 team gold plated the parts.'
    - Sources disagree on density, Young's modulus, shear modulus and expansion. Each value is kept with its own source, and none is averaged.
    - No flight, spacecraft, corrosion or safety data sheet was found in the sources read.
  verdict: CE7 is a silicon-aluminium alloy with expansion, density and cryogenic data from its maker and a 2018 cryogenic test paper. It is brittle, and the sources read give no flight record and no corrosion data.
  risk_groups:
    - title: For people
      lead: No safety data sheet for CE7 was read. The hazard data are the maker's claim and PubChem GHS records for the elements silicon and aluminum.
      points:
        - label: Maker's claim
          line: Osprey says the alloys are safe to handle and use and present no disposal problems (Microwave Journal, 2003).
        - label: Element records
          line: PubChem lists H228 (flammable solid) for some silicon and aluminum notifications, and H261 (releases flammable gas in contact with water) for aluminum, but does not say which physical form each notification covers.
      verdict: Maker says safe; no CE7 SDS read; element records list codes
    - title: If it fails
      lead: The sources describe brittleness rather than failure rates.
      points:
        - label: Brittleness
          line: Yield and ultimate tensile strength are nearly the same, so the alloy shows little plastic deformation before it breaks (arXiv 2018).
        - label: Grain boundaries
          line: Machining near the grain size causes fractures at grain boundaries (arXiv 2018).
      verdict: Brittle; no failure-rate data
    - title: Handling and cooling
      lead: The sources give machining and plating steps, not hazards.
      points:
        - label: Plating
          line: Bare CE7 conducts heat poorly at 300 mK, so the 2018 parts were gold plated (arXiv 2018).
      verdict: Plate for cryogenic use
  recipe:
    line: CE7 is a binary silicon-aluminium alloy, not a powder composite. Osprey makes its controlled expansion alloys by a patented spray-forming process (Microwave Journal, 2003). The 2018 paper describes interwoven continuous silicon and aluminium phases.
    parts:
      - name: Silicon
        symbol: Si
        share_percent: 70
        role: Main phase. It keeps the expansion and density low (LookPolymers composition; arXiv 2018 text).
        source: lookpolymers-ce7
        where: Component Elements Properties table, row Silicon Si, value 70 %
      - name: Aluminium
        symbol: Al
        share_percent: 30
        role: Second continuous phase. The 2018 paper says the aluminium makes CE7 contract more than silicon does.
        source: mwj-osprey-2003
        where: Table 1 Key Properties, row Composition (wt %), column CE7 (printed Si-30% Al)