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Negative Thermal Expansion ALLVAR Alloy 30's strain compared to other common materials.

ALLVAR ALLOY 30 is a Titanium alloy produced by ALLVAR, a manufacturer located in College Station, Texas, since 2014. ALLVAR Alloy 30 exhibits a Negative thermal expansion. It can be used to compensate for the thermal mismatch between dissimilar materials to meter forces or displacement.

ALLVAR Alloy 30 has been used to create athermal telescopes, refractive optics, and constant force-load fastened joints for cryogenic environments. Although it has advantages for optics applications requiring a negative coefficient of thermal expansion for Passive Athermalization, it is more expensive than common optical housing and metering structures. The tight tolerance on CTE, -30×10⁻⁶ C⁻¹ at 25°C allow it to compensate for the expansion and contraction of other materials in high-precision applications.

Contents

• 1 Applications
• 2 Properties
  • 2.1 Physical properties
• 3 See also
• 4 References
• 5 External links

Applications[edit source]

ALLVAR Alloy 30 can be used to compensate for the thermal mismatch between dissimilar materials to meter forces or displacement. A very low thermal expansion strut with an ALLVAR Alloy 30 metering rod is shown.

1. Ultra-stable telescopes
2. Optics
3. Space structures
4. Cryogenic instrumentation
5. Precision machining

Properties[edit source]

ALLVAR Alloy 30 is a fully dense titanium alloy.

• Negative thermal expansion: -30ppm/°C at 25°C with a mean CTE of -29ppm/°C between -40°C and 80°C.
• Machinability similar to other titanium alloys.
• Nonmagnetic

Physical properties[edit source]

• Density: 5.08 g/cm³
• Coefficient of thermal expansion (-40 °C to 80 °C): 29 ± 0.10×10⁻⁶/K
• Thermal conductivity: 6.2 - 8.7 W/(m·K)
• Maximum application temperature: 100 °C
• Yield Stress: 405 MPA
• Ultimate tensile strength: 800 MPA
• Elastic modulus: 75 GPA

See also[edit source]

• Negative Thermal Expansion
• Athermalization
• Thermal expansion