4J32

4J32 (UNS K93600) is a low-expansion iron-nickel-cobalt alloy (also known as "Invar 32 – 5") optimized for ultra-low thermal expansion coefficient and excellent dimensional stability. This alloy contains approximately 32% nickel and 5% cobalt, which together form a unique crystal structure that minimizes thermal expansion across a wide temperature range—unlike soft magnetic alloys such as 1J79, which prioritize magnetic properties. It maintains stable dimensions from -60 °C to 200 °C (212°F to 392°F) and is widely used in industries requiring extreme dimensional precision, such as aerospace instrumentation, precision optical equipment, and microelectronics, where even minimal thermal deformation could compromise performance.

Behaviour that matters in service

• Ultra-Low Thermal Expansion — The 31 – 33% nickel and 4.5 – 5.5% cobalt content forms a face-centered cubic (FCC) structure with minimal lattice expansion under temperature changes—resulting in a thermal expansion coefficient as low as 1.5×10⁻⁶/°C (20 – 100 °C), ideal for precision components requiring dimensional stability.
• Excellent Dimensional Stability — Maintains near-constant dimensions across a wide temperature range (-60 °C to 200 °C), avoiding thermal deformation that could disrupt alignment in optical systems or electrical connections in microelectronics.
• Good Mechanical Properties — Balances low expansion with sufficient tensile strength (≥500 MPa) and ductility (≥25% elongation), enabling fabrication of complex-shaped components without compromising structural integrity.
• Precision Fabricability — Can be cold-rolled to thin strips with tight dimensional tolerance (±0.001 mm) and machined with high precision using carbide tools; post-fabrication stress relief annealing (600 – 700 °C for 1 – 2 hours) further enhances dimensional stability by eliminating residual stresses.
• Basic Corrosion Resistance — Offers moderate resistance to atmospheric oxidation and mild humidity, suitable for indoor precision equipment; for harsh environments (e.g., marine or industrial atmospheres), surface coating (e.g., nickel plating or passivation) is recommended to prevent rusting.

Typical applications

• Precision Optical Equipment — Used in optical lens mounts, mirror supports, and laser alignment components for telescopes, microscopes, and laser processing machines—ensuring optical alignment remains stable under temperature fluctuations.
• Aerospace & Defense — Applied in gyroscope frames, satellite antenna brackets, and missile guidance system components—withstanding extreme temperature variations in space or high-altitude environments while maintaining dimensional accuracy.
• Microelectronics & Semiconductors — Utilized in semiconductor wafer chucks, precision lead frames, and microchip packaging components—preventing thermal warping that could damage delicate electronic circuits during manufacturing or operation.
• Metrology & Test Instruments — Suitable for precision measuring tools (e.g., coordinate measuring machine (CMM) probes), standard gauges, and calibration blocks—providing consistent dimensions for accurate measurement across different ambient temperatures.
• Medical Precision Equipment — Employed in surgical laser guides, medical imaging device components (e.g., CT scanner collimators), and implantable device housings—ensuring dimensional stability in body temperature or sterilization cycles.
• Automotive Precision Components — Used in advanced driver-assistance system (ADAS) sensor mounts (e.g., LiDAR and camera brackets), ensuring sensor alignment remains accurate to avoid misinterpretation of road conditions.