Negative Thermal Expansion

What is Negative Thermal Expansion?

Negative Thermal Expansion proven by comparing ALLVAR's Negative Strain to other materials

Thermal expansion refers to a material’s natural increase in size with increasing temperature. While all other metals in the world expand alongside increasing temperature, ALLVAR Alloys are designed to shrink with increasing temperature. This shrinking while heating is known as a negative thermal expansion (Negative CTE).

This revolutionary property can compensate for the expansion or contraction of other materials in the world’s most demanding thermal stability applications. Spaceborne telescopes, high performance optical assemblies, and the secure transport of petrochemicals are a few of the applications that require enhanced stability and performance when operating under extreme shifting thermal environments. 

Negative CTE alloys can be used as compensating elements or metering structures to passively athermalize optics or create ultra stable struts for telescopes. Outside of its optics applications, negative CTE enabled washers or spacers can be used to maintain a constant-force load across a wide temperature range.

How do Negative CTE ALLVAR Alloys compare to other alloys?

Property Units ALLVAR Alloy Invar 304 Stainless Steel 6061 Aluminum Titanium 64
CTE Range @20°C
(ppm/°C)
-30
1.6 to 6
17.3
23.6
9
Max Operating Temperature
(°C)
100
200
870
120
540
Yield Stress
(MPa)
405
276
215
55
828
UTS
(MPa)
800
448
505
124
895
Elastic Modulus
(GPa)
75
141
193
68.9
113.8
Density
(g/cc)
5.08
8.1
8.0
2.7
4.42
Thermal Conductivity
(W/m·K)
8.88
10.15
16.2
180
6.6

Do you offer Negative CTE alloys at temperatures higher than 100 degrees C?

Yes. Additional alloys that can withstand higher temperature ranges were developed as part of a NASA SBIR grant. If you are interested in a higher temperature capable alloy, please contact us with more details on your application and desired temperature ranges so we can find the best athermalization solution for you.

Where can I learn more about your alloys?

You can start by visiting our FAQ page and our video library for demonstrations and discussions.  Our News page also has information about our work to develop negative thermal expansion enabled technologies like ultra-stable struts, athermal optics, and constant-force load washers. You can also contact us for more information.

You can also find more information on ALLVAR Alloy 30’s matweb.com page or read published SPIE proceedings on SPIE’s Digital Library.

Contact Us Today to Revolutionize Your Thermal Performance

Have an application in mind? Please let us know if you have any questions.

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