Beryllium

Beryllium is a hard, brittle, gray-white metal with physical and mechanical properties, including high heat capacity and thermal conductivity, that make it especially suitable for electronic components and specialized aerospace applications. Beryllium is particularly well suited for use as a structural material in space technology as it is the lightest structural metal known. Because of its combination of low weight, high stiffness and certain mechanical properties, such as a precise elastic limit, and transparency to x-rays and other high-energy electromagnetic radiation, beryllium is an excellent material for use in optical components and precision instruments. Beryllium is also used as an alloying element in copper, nickel, aluminum and magnesium alloys. 

Typical Properties:

• Crystal Structure:
  
  • α phase, close-packed hexagonal; a = 0.22858 nm, c = 0.35842 nm at room temperature
  • β phase, body-centered cubic; a = 0.255 nm at 1270 ^oC
• Atomic Weight: 9.0122
• Density: 1.848 g/cm³ at 20 ^oC
• Melting Point: 1283 ^oC
• Boiling Point: 2770 ^oC
• Coefficient of Linear Thermal Expansion: 18.4 µm/m ⋅ K (average coefficient), 25 ^oC - 1000 ^oC
• Specific Heat: 1.886 kJ/kg ⋅ K at 20 ^oC
• Latent Heat of Fusion: 1.30 MJ/kg
• Thermal Conductivity: 210 W/m ⋅ K
• Electrical Conductivity: 38 to 43% IACS
• Electrical Resistivity: 40 nΩ ⋅ m at 20 ^oC
• Temperature Coefficient of Electrical Resistivity: 0.025 Δρ/ρ₍₎/K
• Magnetic Susceptibility:  Mass: 
  
  • -0.79 x 10^-9 mks at 93 K
  • -1.0 x 10^-9 mks at 293 K
  • -1.2 x 10^-9 mks at 573 K
• Spectral Hemispherical Emittance: 61% for λ = 650 nm
• Thermal Neutron Cross Section: 0.01 b
• Hardness: 75 to 85 HRB
• Poisson’s Ratio: 0.07 to 0.075 (vacuum hot pressed)
• Elastic Modulus: 303 GPa
• Impact Strength: 1.4 to 5.4 J
• Plane-Strain Fracture Toughness: 9 to 13 MPa√m
• Resistance to Specific Corroding Agents: Beryllium reacts appreciably with oxygen and nitrogen above 760 ^oC. Impure beryllium containing carbide or chloride reacts with moist air at room temperature. Beryllium does not react with hydrogen at any temperature; it reacts with fluorine at room temperature and with Cl, B, I, HCl, HF, and CO₂ at elevated temperatures. Beryllium has excellent resistance to pure water at temperatures up to 300 ^oC if carbide and chloride are absent and if grain size is fine. Beryllium is attacked by dilute HF, HCl, H₂SO₄, and HNO₃, at room temperature.