Beryllium Copper is a copper alloy used in aerospace applications. Melting point: 870 °C. Tensile strength: 1,380 MPa.
Some spacecraft parts have to do several hard jobs at once: carry electricity, shed heat, and spring back into shape after years of shaking without ever wearing out. Beryllium copper is the metal engineers reach for when one part has to do all of that.
Quick facts
- What it is: A high-strength copper alloy (a metal blend) made of copper plus roughly 0.5-3% beryllium, a light, stiff metal. Also called copper beryllium, BeCu, or “spring copper.”
- Common grades: Wrought types like C17200 and C17500; cast types like C82000-C82800.
- Strength: Tensile strength up to about 1,400 megapascals (200,000 psi) when fully hardened – approaching steel.
- Hardness: About Rockwell C45 (a standard hardness scale).
- Heat flow: Thermal conductivity around 107 watts per meter-kelvin, roughly 3-5 times that of tool steel.
- Electricity: Conducts nearly as well as plain copper.
- Melting range: About 866-982 degrees Celsius (1,590-1,800 degrees Fahrenheit).
- Bonus traits: Non-sparking, non-magnetic, and corrosion-resistant (even in seawater).
What it is and how it works
Beryllium copper is a precipitation-hardening alloy, which means its strength is built in two stages. In its soft, “solution-annealed” starting state the metal is bendy and easy to machine or shape into springs, contacts, and complex parts. After shaping, it is heat-treated – usually held at a few hundred degrees Celsius for an hour or more. That heat causes tiny crystals called beryllides to form throughout the copper. Think of those crystals like grains of sand mixed into wet cement: once they set, they lock the structure in place. The result is a part that still conducts electricity and heat almost like copper, but now springs back again and again without tiring and resists wear like hardened steel.
Because beryllium is non-magnetic and the alloy will not throw sparks when struck, it is safe to use near magnetically sensitive instruments and around fuel-rich or explosive atmospheres.
Why it matters
Spacecraft and launch vehicles need components that are strong, fatigue-resistant (able to flex repeatedly without cracking), electrically and thermally conductive, non-magnetic, and dependable for an entire mission. That is a rare combination to find in one material. Beryllium copper’s springiness keeps electrical connector contacts pressed firmly together through violent vibration and big temperature swings. That is why it underpins “no-fail” aerospace connectors, including the fly-by-wire connectors in commercial airliners. Its heat conductivity helps pull warmth away from high-performance electronics. Its non-sparking, non-magnetic nature suits fuel-handling areas and guidance instruments where magnetic interference cannot be tolerated. Lightweight BeCu bearings and bushings also trim structural weight.
The main trade-offs: beryllium dust and fumes created during machining are a health hazard requiring ventilation and controlled handling (finished solid parts are safe to handle), and the alloy is relatively expensive. Designers can also tune the balance of strength versus conductivity by adjusting the heat-treatment cycle, choosing high-strength grades like C17200 or higher-conductivity grades like C17500.
Where it is used
- Electrical and electronic connectors: BeCu contact springs are standard in high-reliability connectors, including airliner fly-by-wire systems and satellite and spacecraft wiring harnesses.
- Guidance and navigation systems: Copper-beryllium gyroscope gimbals and yokes in aircraft, vehicle, and missile guidance, where non-magnetic behavior is essential.
- Landing-gear and control hardware: Low-friction, high-strength bearings, bushings, and control-rod and aileron bushings that cut weight.
- Precision instruments: Altimeter and pressure diaphragms, bellows, and springs in flight instrument panels.
- Sealed extreme environments: Undersea fiber-optic “repeater” (signal-amplifier) housings, showing reliability and corrosion resistance much like space hardware.
One common mix-up worth clearing up: the James Webb Space Telescope’s mirrors and the Spirit and Opportunity Mars rover structures use pure beryllium metal, not beryllium copper. They are different materials. Even so, about 80% of all beryllium produced ends up in copper-beryllium alloys.
Cu 97-98%, Be 1.8-2.0%, Co 0.2-0.3%
| DENSITY | 8 kg/m³ |
| TENSILE STRENGTH | 1,380 MPa |
| YIELD STRENGTH | 1,170 MPa |
| STRENGTH-TO-WEIGHT | 167272.7 kN·m/kg |
| MELTING POINT | 870 °C |
| MAX SERVICE TEMPERATURE | 315 °C |
| THERMAL CONDUCTIVITY | 115 W/m·K |
| THERMAL EXPANSION | 17.8 µm/m·K |
| CATEGORY | Copper Alloy |
| DESIGNATIONS | UNS C17200, AMS 4650, CDA 172 |
| MANUFACTURER | Materion (Brush Wellman) |
| DENSITY | 8 kg/m³ |
| TENSILE STRENGTH | 1,380 MPa |
| YIELD STRENGTH | 1,170 MPa |
| MELTING POINT | 870 °C |
| MAX SERVICE TEMP | 315 °C |
| THERMAL CONDUCTIVITY | 115 W/m·K |
| THERMAL EXPANSION | 17.8 µm/m·K |
| CORROSION RESISTANCE | Good |
| WELDABILITY | Fair |
| MACHINABILITY | Good |
| COST RATING | High |
