Expansion Alloys - Plus Metals

EXPANSION ALLOYS

ALLOY 36 (INVAR 36)

ALLOY 36, commonly known as INVAR 36, is a nickel-iron alloy renowned for its exceptional low thermal expansion characteristics. This alloy is primarily composed of approximately 36% nickel, with the remainder being iron. Its name, "Invar," is derived from the Latin word "invariabilis," meaning "invariable," which reflects its minimal expansion and contraction with changes in temperature. The alloy was first developed in the early 20th century by Swiss physicist Charles Édouard Guillaume, who was awarded the Nobel Prize in Physics for his work on the material. Due to its unique thermal expansion properties, ALLOY 36 is crucial in applications requiring high precision and stability under varying thermal conditions.

Composition
  • Carbon (C): Max 0.10%
  • Manganese (Mn): Max 0.06%
  • Silicon (Si): Max 0.35%
  • Phosphorus (P): Max 0.02%
  • Sulfur (S): Max 0.025%
  • Nickel (Ni): Min 35%, Max 38%
  • Chromium (Cr): Max 0.50%
  • Molybdenum (Mo): Max 0.50%
  • Cobalt (Co): Max 1.0%
  • Iron (Fe): Balance
Properties
  • Coefficient of Thermal Expansion: Approximately 1.2 x 10-6 /°C, which is significantly lower than most other metals.
  • Density: About 8.1 g/cm³.
  • Thermal Conductivity: Roughly 11 W/m·K, which is relatively low compared to other metals, contributing to its stable temperature properties.
  • Magnetic Properties: ALLOY 36 is ferromagnetic, meaning it can be magnetized.
  • Mechanical Properties: Good mechanical strength and stability, though not as high as some other alloys.
Applications
  • Metal-to-glass seals for electronic tubes and hermetic devices.
Advantages
  • Minimal Thermal Expansion: The primary advantage of ALLOY 36 is its extremely low coefficient of thermal expansion, making it ideal for applications where dimensional stability is critical.
  • Dimensional Accuracy: Its stability under temperature fluctuations ensures high precision in various industrial and scientific applications.
  • Magnetic Properties: The ferromagnetic nature of the alloy can be advantageous in certain magnetic applications.
Limitations
  • Cost: The inclusion of nickel makes ALLOY 36 more expensive than other alloys with higher thermal expansion coefficients.
  • Strength: While it offers good stability, it does not possess the same level of mechanical strength or hardness as some other high-strength alloys, which may limit its use in applications requiring high mechanical performance.
  • Workability: The alloy can be more challenging to machine and process compared to other more ductile metals, which may impact manufacturing efficiency.

ALLOY 42 (INVAR 42)

ALLOY 42, also known as INVAR 42, is a high-nickel iron alloy characterized by its low coefficient of thermal expansion. This alloy contains approximately 42% nickel, which provides it with superior dimensional stability across a wide range of temperatures. INVAR 42 is an evolution of the original INVAR 36, offering enhanced thermal expansion properties. The alloy's name, "Invar," comes from the Latin word "invariabilis," meaning "invariable," reflecting its minimal thermal expansion. Developed in the early 20th century, INVAR 42 has been used in various high-precision applications where stability is crucial.

Composition
  • Nickel (Ni): Min 41%
  • Carbon (C): Max 0.05%
  • Manganese (Mn): Max 0.80%
  • Phosphorus (P): Max 0.025%
  • Sulfur (S): Max 0.025%
  • Silicon (Si): Max 0.030%
  • Chromium (Cr): Max 0.250%
  • Aluminum (Al): Max 0.10%
  • Iron (Fe): Balance
Properties
  • Coefficient of Thermal Expansion: Approximately 1.0 x 10-6 /°C, which is even lower than that of INVAR 36.
  • Density: About 8.1 g/cm³.
  • Thermal Conductivity: Around 11 W/m·K, contributing to stable temperature properties.
  • Magnetic Properties: INVAR 42 is ferromagnetic and can be magnetized.
  • Mechanical Properties: Offers good mechanical strength and stability, though less than some high-strength alloys.
Applications
  • Glass to metal seals for a wide variety of electronic tubes, hermetic packages, automotive and industrial lamps.
Advantages
  • Extremely Low Thermal Expansion: INVAR 42 has an exceptionally low coefficient of thermal expansion, making it highly suitable for precision applications where dimensional stability is essential.
  • High Dimensional Stability: Its stability under varying temperatures ensures accurate performance in critical applications.
  • Magnetic Properties: The ferromagnetic nature of the alloy is useful in certain magnetic applications.
Limitations
  • Cost: The higher nickel content makes INVAR 42 more expensive compared to alloys with higher thermal expansion coefficients.
  • Strength: While it provides good stability, it does not have the same level of mechanical strength or hardness as some high-performance alloys, limiting its use in high-stress applications.
  • Machinability: INVAR 42 can be more challenging to machine compared to more ductile metals, which can affect manufacturing processes.

ALLOY 48 (INVAR 48)

ALLOY 48, also known as INVAR 48, is a nickel-iron alloy that offers a very low coefficient of thermal expansion, making it suitable for applications requiring high precision and dimensional stability over a range of temperatures. Containing approximately 48% nickel, INVAR 48 builds upon the properties of its predecessors, such as INVAR 36, by providing even better thermal stability. The alloy's name "Invar" derives from the Latin "invariabilis," meaning "invariable," highlighting its minimal thermal expansion characteristics. Developed to meet demanding specifications in precision engineering, INVAR 48 is employed in various high-tech and scientific applications.

Composition
  • Nickel (Ni): Min 48%
  • Chromium (Cr): Max 0.25%
  • Manganese (Mn): Max 0.80%
  • Silicon (Si): Max 0.30%
  • Carbon (C): Max 0.05%
  • Aluminum (Al): Max 0.10%
  • Phosphorus (P): Max 0.025%
  • Sulfur (S): Max 0.025%
  • Iron (Fe): Balance
Properties
  • Coefficient of Thermal Expansion: Approximately 0.9 x 10-6 /°C, which is lower than that of INVAR 36 and INVAR 42.
  • Density: About 8.1 g/cm³.
  • Thermal Conductivity: Around 11 W/m·K, contributing to its stable temperature characteristics.
  • Magnetic Properties: INVAR 48 is ferromagnetic and can be magnetized.
  • Mechanical Properties: Good mechanical strength and stability, though less than some high-strength alloys.
Applications
  • Glass-to-metal seals for electronic tubes and hermetic devices.
Advantages
  • Extremely Low Thermal Expansion: INVAR 48 features a very low coefficient of thermal expansion, making it excellent for precision applications where thermal stability is essential.
  • High Dimensional Stability: Ensures accurate performance in environments with fluctuating temperatures.
  • Magnetic Properties: Useful in applications where ferromagnetic properties are required.
Limitations
  • Cost: Higher nickel content makes INVAR 48 more expensive compared to alloys with higher thermal expansion coefficients.
  • Strength: Although it offers excellent stability, it does not possess the same mechanical strength or hardness as some other high-performance alloys, limiting its use in high-stress applications.
  • Machinability: Can be more challenging to machine compared to more ductile metals, potentially affecting manufacturing efficiency.

ALLOY 49 (INVAR 49)

ALLOY 49, also known as INVAR 49, is a nickel-iron alloy that exhibits a very low coefficient of thermal expansion, making it ideal for high-precision applications where dimensional stability is critical. This alloy contains approximately 49% nickel, which further enhances its ability to maintain its shape and dimensions across a wide range of temperatures. The "Invar" name, derived from the Latin "invariabilis" (invariable), reflects the alloy’s minimal thermal expansion. Developed for demanding engineering and scientific applications, INVAR 49 builds on the properties of other Invar alloys, offering superior performance in environments requiring high accuracy.

Composition
  • Carbon (C): Max 0.035%
  • Manganese (Mn): Max 0.8%
  • Silicon (Si): Max 0.5%
  • Phosphorus (P): Max 0.02%
  • Sulfur (S): Max 0.008%
  • Nickel (Ni): Min 47%, Max 50%
  • Iron (Fe): Balance
Properties
  • Coefficient of Thermal Expansion: Approximately 0.8 x 10-6 /°C, which is lower than that of INVAR 36, INVAR 42, and INVAR 48, providing even better thermal stability.
  • Density: About 8.1 g/cm³.
  • Thermal Conductivity: Approximately 11 W/m·K, contributing to its stable thermal properties.
  • Magnetic Properties: INVAR 49 is ferromagnetic and can be magnetized.
  • Mechanical Properties: Provides good mechanical strength and dimensional stability, though it may be less than some other high-strength alloys.
Applications
  • Alloy 49 is used in research equipment and devices where maintaining exact measurements and stability across varying temperatures is essential for experimental accuracy.
Advantages
  • Exceptional Thermal Stability: INVAR 49 has a very low coefficient of thermal expansion, making it suitable for applications that require high precision and stability over a wide temperature range.
  • High Dimensional Accuracy: Ensures precise performance and accuracy in environments with fluctuating temperatures.
  • Magnetic Properties: The ferromagnetic properties can be advantageous in specific magnetic applications.
Limitations
  • Cost: The high nickel content makes INVAR 49 more expensive compared to alloys with higher thermal expansion coefficients.
  • Strength: While it offers excellent dimensional stability, it does not match the mechanical strength or hardness of some other high-performance alloys, limiting its use in high-stress applications.
  • Machinability: Can be more challenging to machine compared to more ductile metals, which may impact production efficiency.

SUPRA 510 (NI50FE)

Supra 510, also known as NI50FE, is a nickel-iron alloy with a nominal composition of 50% nickel and 50% iron. This alloy is designed to exhibit a low coefficient of thermal expansion, making it suitable for precision applications where dimensional stability is essential. It is commonly used in environments where temperature fluctuations occur, requiring the material to maintain its shape and size accurately. Supra 510 is used in various high-precision applications due to its balanced properties of thermal stability and mechanical performance.

Composition
  • Carbon (C): Max 0.03%
  • Manganese (Mn): Min 0.30%, Max 0.60%
  • Silicon (Si): Min 0.15%, Max 0.30%
  • Phosphorus (P): Max 0.02%
  • Sulfur (S): Max 0.02%
  • Nickel (Ni): Min 49%, Max 51%
  • Copper (Cu): Max 0.20%
  • Iron (Fe): Balance
Properties
  • Coefficient of Thermal Expansion: Approximately 1.0 x 10-6 /°C, providing a low but slightly higher expansion rate compared to some other low-expansion alloys.
  • Density: About 8.0 g/cm³.
  • Thermal Conductivity: Approximately 12 W/m·K, supporting its stable thermal properties.
  • Magnetic Properties: NI50FE is generally ferromagnetic and can be magnetized, though its magnetic properties can vary with composition.
  • Mechanical Properties: Offers a good balance of strength and stability, suitable for precision applications but not as strong as some high-strength alloys.
Applications
  • In structural components, support and substrates require precision measurements such as optical and laser systems, telescopes, laser bench tops, and ring gyroscopes.
Advantages
  • Good Thermal Stability: Supra 510 offers a low coefficient of thermal expansion, making it suitable for precision applications with moderate temperature variations.
  • Balanced Mechanical Properties: Provides a good combination of dimensional stability and mechanical strength.
  • Magnetic Properties: The ferromagnetic nature can be beneficial for specific magnetic applications.
Limitations
  • Cost: The cost may be higher compared to alloys with higher thermal expansion coefficients due to its composition and performance characteristics.
  • Strength: While offering good dimensional stability, it may not match the mechanical strength or hardness of some specialized high-performance alloys.
  • Machinability: Machining can be more challenging compared to more ductile metals, which might affect production efficiency.

KOVAR

Kovar is a nickel-cobalt-iron alloy known for its low coefficient of thermal expansion, which makes it highly compatible with glass and ceramics. It contains approximately 29% cobalt, 17% nickel, and the balance is primarily iron. Kovar’s properties make it particularly useful in electronic and electrical applications, especially where a consistent thermal expansion is crucial to prevent cracking or failure. Developed for high precision and reliability, Kovar is often used in the fabrication of electronic components, lead-throughs, and various sealing applications.

Composition
  • Carbon (C): Max 0.04%
  • Manganese (Mn): Max 0.50%
  • Silicon (Si): Min 0.20%
  • Nickel (Ni): Min 29%
  • Iron (Fe): Min 53%
  • Cobalt (Co): Max 17%
  • Aluminum (Al): Max 0.10%
  • Chromium (Cr): Max 0.20%
  • Magnesium (Mg): Max 0.10%
  • Zirconium (Zr): Max 0.10%
  • Titanium (Ti): Max 0.10%
  • Copper (Cu): Max 0.20%
  • Molybdenum (Mo): Max 0.20%
Properties
  • Coefficient of Thermal Expansion: Approximately 5.0 x 10-6 /°C, which is close to that of borosilicate glass, making it ideal for glass-sealing applications.
  • Density: About 8.2 g/cm³.
  • Thermal Conductivity: Approximately 13 W/m·K, contributing to its stable thermal performance.
  • Magnetic Properties: Kovar is generally magnetic due to its iron content.
  • Mechanical Properties: Provides good mechanical strength and ductility, which allows it to be processed into various shapes and forms for different applications.
Applications
  • Power tubes, microwave tubes, transistors, diodes and hybrid packages.
Advantages
  • Low Thermal Expansion: The alloy’s low coefficient of thermal expansion makes it highly suitable for applications involving glass and ceramics.
  • Compatibility: Excellent compatibility with glass and ceramics ensures reliable sealing and bonding.
  • Mechanical Strength: Provides good mechanical strength and ductility for various applications.
Limitations
  • Cost: The alloy’s composition and specific properties can make it more expensive than other materials with higher thermal expansion.
  • Machinability: Can be more challenging to machine compared to more ductile metals, which might impact production efficiency.
  • Magnetic Properties: Its magnetic properties may not be suitable for applications requiring non-magnetic materials.

VIM VAR CORE IRON

VIM VAR Core Iron is a high-purity iron alloy produced through Vacuum Induction Melting (VIM) and Vacuum Arc Remelting (VAR) processes. This refined alloy is known for its exceptional purity, low carbon content, and controlled alloying elements, which contribute to its superior magnetic and mechanical properties. VIM VAR Core Iron is primarily used in applications requiring high magnetic permeability, low core loss, and stable magnetic properties over a range of temperatures. It is extensively used in electrical and electronic applications, such as transformers, inductors, and magnetic shielding.

Composition
  • Carbon (C): Max 0.020%
  • Manganese (Mn): Max 0.35%
  • Silicon (Si): Max 0.15%
  • Phosphorus (P): Max 0.030%
  • Sulfur (S): Max 0.025%
  • Chromium (Cr): Max 0.20%
  • Nickel (Ni): Max 0.15%
  • Vanadium (V): Max 0.10%
  • Titanium (Ti): Max 0.10%
  • Aluminum (Al): Max 0.10%
  • Iron (Fe): Balance
Properties
  • Magnetic Permeability: High magnetic permeability, making it ideal for use in magnetic cores and components.
  • Core Loss: Low core loss, which contributes to the efficiency of electrical devices.
  • Density: Approximately 7.9 g/cm³.
  • Electrical Resistivity: Low electrical resistivity, which supports efficient magnetic performance.
  • Mechanical Properties: Good mechanical strength and ductility, though primarily optimized for magnetic applications.
Applications
  • Soft magnetic components where vacuum integrity is needed such as power tubes and microwave devices, in addition, relays, solenoids, and magnetic pole pieces for scientific instruments.
Advantages
  • High Magnetic Permeability: Provides excellent performance in magnetic applications due to its high permeability.
  • Low Core Loss: Minimizes energy losses in electrical components, enhancing overall efficiency.
  • Purity and Consistency: The VIM VAR production process ensures high purity and consistency in properties, critical for high-performance applications.
Limitations
  • Cost: The high-purity production methods (VIM and VAR) can make VIM VAR Core Iron more expensive compared to other core materials.
  • Specific Use: Its properties are optimized for magnetic applications, making it less suitable for structural or high-strength applications.
  • Machinability: The alloy’s properties may make it more challenging to machine compared to more ductile materials, which can impact production processes.

EXPANSION ALLOYS

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