Tungsten
W
Description
Tungsten, also known as wolfram, is a dense, silvery-white transition metal. It is defined by its extreme physical robustness, holding the record for the highest melting point of all elements in pure form. It is a critical refractory metal used in high-stress, high-temperature industrial environments.
Crystallographic Structure
Tungsten predominantly crystallizes in the Body-Centered Cubic (BCC) lattice (the $\alpha$-phase). This structure is less densely packed than FCC or HCP systems, contributing to its distinct mechanical properties.
- Crystal System: Cubic (BCC)
- Lattice Parameter: $a = 3.1652$ Å
- Coordination Number: 8
- Atomic Packing Factor (APF): 0.68
- Space Group: $Im\bar{3}m$
Properties
- Atomic Number: 74
- Atomic Mass: 183.84 u
- Melting Point: 3,422°C
- Boiling Point: 5,930°C
- Density: $19.3\text{ g/cm}^3$ (Similar to gold)
- Tensile Strength: Highest of all metals at temperatures above 1,650°C.
- Thermal Expansion: Very low coefficient, nearly matching that of borosilicate glass.
Applications
High-Temperature Filaments: Used in incandescent light bulbs, cathode ray tubes, and vacuum tube filaments.
Industrial Tooling: Used to create Tungsten Carbide ($WC$), a ceramic-metal composite used for high-speed cutting tools, drill bits, and abrasives.
Aerospace & Military: Utilized in rocket engine nozzles, counterweights, and kinetic energy penetrators.
Electrodes: Essential for Gas Tungsten Arc Welding (TIG welding) due to its ability to withstand intense arc heat without melting.
Unit Cell Axes
a=3.16 b=3.16 c=3.16
Unit Cell Angles
α=90° β=90° γ=90°
Lattice Type
bcc
Grid Expansion
Appearance
Coordination