When precision matters most in engineering applications, the question of which alloy has the smallest coefficient of thermal expansion becomes critical. The answer lies in a specialized class of materials known as low expansion alloys, with super-invar standing out as the ultimate performer.
Super-invar, a remarkable iron-nickel-cobalt alloy, boasts the lowest thermal expansion coefficient among commercially available alloys. With a composition of approximately 31-33% nickel, 4-6% cobalt, and the balance iron, it achieves an astonishingly low linear expansion coefficient of just 0.7*10⁻⁶/°C within the 20-100°C range--half that of standard invar alloys. This exceptional stability comes from the precise balance of elements that minimizes atomic movement during temperature fluctuations.
Invar 36 (Alloy 36) serves as the foundation for low expansion materials, containing 36% nickel and 64% iron. It exhibits a very low coefficient of about 1.2*10⁻⁶/°C between 20°C and 230°C, making it ideal for general precision applications. Our product lineup includes both invar 36 and super-invar, providing solutions across temperature ranges and precision requirements.
Our low expansion alloys offer more than just dimensional stability. They combine exceptional mechanical properties with their low expansion characteristics. Invar 36 maintains good strength and toughness even at cryogenic temperatures, while super-invar delivers unparalleled precision for the most demanding environments. Both alloys are readily machinable and weldable, ensuring manufacturability for complex components.
These materials excel in critical applications: from optical instrument components and telescope structures to aerospace navigation systems and precision electronic devices. In the electronics industry, they enable reliable glass-to-metal seals and stable performance in sensors and actuators. Our vacuum induction melting process ensures exceptional purity and homogeneity, enhancing material consistency.
Whether your application requires the broad temperature range stability of invar 36 or the ultra-precise performance of super-invar, our low expansion alloys provide the dimensional control needed for today's most advanced technologies. Contact us to discover how our materials can elevate the precision and reliability of your products.