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BYP40 (4J48) Controlled-Expansion Alloy is a precision-engineered nickel-iron-copper alloy designed for applications requiring reliable sealing with soft glasses or ceramics. Featuring a carefully controlled linear expansion coefficient ranging from 9.2 to 10.4 × 10⁻⁶/°C across 25°C to 500°C, this alloy ensures excellent dimensional stability under thermal cycling. With a balanced composition of 46-48% Ni, iron as the remainder, and 4.5-5.5% copper, BYP40 controlled expansion alloys offers a combination of moderate tensile strength, good hardness, and superior mechanical and physical properties including a density of 8.17 g/cm³ and elastic modulus of 178 GPa. Ideal for critical precision applications, BYP40 delivers consistent performance and durability.
Sealing alloys for soft glasses or ceramics
| Ni | 46.0~48.0 | Fe | bal. |
Cu | 4.5~5.5 |
25℃-300℃ | 9.2~10.1 |
| 25℃-400℃ | 9.3~10.0 |
25℃-500℃ | 9.8~10.4 (α, 10-6℃-1) |
Tensile Strength | Soft | Hard |
<590 MPa (85.6 ksi) | >700 Mpa (101.5 ksi) | |
Hardness | Deep-drawing State: ≤190HV | |
Gain Size | Deep-drawing State: ≥Level 7 |
| Density | 8.17 g/cm3 (0.295 lb/in3) |
| Resistivity | 80 µΩ•cm |
Thermal conduction | 17 W/K |
Elastic modulus | 178 Gpa |
For consistent performance as detailed in these properties, we recommend sourcing your BYP40 (4J48) material from Beiye. Please contact our team for a formal quote on this critical precision alloy and supply.
