Tungsten has the highest melting point of all metals at 3422°C (6192°F).
Factors Affecting Tungsten's Melting Point
Purity of Tungsten: The purity of tungsten significantly affects its melting point. Pure tungsten has a melting point of 3422°C, but other elements (such as molybdenum, iron, chromium, etc.) in tungsten alloys may alter the melting point, usually lowering it slightly. The type and content of alloying elements directly influence the melting point.
Crystal Structure: Tungsten typically has a body-centered cubic (BCC) crystal structure, which provides high thermal stability, contributing to its very high melting point.
Pressure Conditions: Under extremely high pressure, the melting point of metals may change. In such conditions, the melting point of tungsten may slightly increase because high pressure tends to compact the metal’s crystal structure, raising its melting temperature.
Although tungsten has an extremely high melting point, these factors still influence its melting point and melting behavior to some extent.
Why Tungsten Has a High Melting Point
Strong Metallic Bonds: Tungsten atoms are held together by strong metallic bonds, and tungsten’s atomic radius is relatively large, leading to strong interactions between atoms. This requires more energy to break these metallic bonds, resulting in its extremely high melting point.
Crystal Structure: Tungsten’s body-centered cubic (BCC) crystal structure provides excellent thermal stability, allowing tungsten to maintain a stable lattice arrangement at high temperatures. In comparison to other crystal structures like face-centered cubic (FCC), metals with BCC structures generally have higher melting points.
High Atomic Nucleus Charge: Tungsten’s atomic nucleus contains 74 protons, which gives it a higher nuclear charge, enhancing the attraction between atoms. This helps tungsten maintain its lattice structure at high temperatures, resisting melting.
Electron Configuration: Tungsten’s outer electron configuration further strengthens the stability of its metallic bonds. Even at high temperatures, tungsten’s electron cloud structure remains stable, contributing to its high melting point.
Application of Tungsten
Tungsten, with its high melting point of 3422°C, is widely used in aerospace, electrical electronics, nuclear energy, metal processing, and military fields.
In aerospace, tungsten is used to manufacture high-temperature components, such as rocket nozzles and reentry vehicle shells; in the electrical industry, it is used for filaments and electron tube electrodes; in nuclear energy, it serves as shielding material to withstand high temperatures and radiation; in metal processing, tungsten is used to make high-temperature cutting tools and molds; and in the military, its high density and melting point make it a key material for armor-piercing projectiles and missile components.
Tungsten’s high melting point makes it valuable in applications under extreme temperatures and harsh environments.
Tungsten Melting Point Comparison with Other Metals
| Metal | Melting Point | Melting Point (°F) |
| Tungsten (W) | 3422°C | 6192°F |
| Platinum (Pt) | 1768°C | 3214°F |
| Gold (Au) | 1064°C | 1947°F |
| Molybdenum (Mo) | 2623°C | 4743°F |
| Iron (Fe) | 1538°C | 2800°F |
| Copper (Cu) | 1085°C | 1985°F |
| Aluminum (Al) | 660°C | 1220°F |
Tungsten Alloys Melting Point
| Tungsten Alloy | Melting Point |
| Tungsten-Copper (W-Cu) | ~2500°C |
| Tungsten-Nickel-Iron (W-Ni-Fe) | 2800°C – 3100°C |
| Tungsten-Molybdenum (W-Mo) | ~3000°C |
| Tungsten-Tantalum (W-Ta) | ~3000°C |
| Tungsten-Bismuth (W-Bi) | ~2400°C |
How to Melt Tungsten Alloys
Melting tungsten alloys is a challenging task due to their extremely high melting point. Special equipment and high-temperature processes are typically required. Here are common methods for melting tungsten alloys:
Arc Melting
Principle: Arc melting uses the high-temperature heat produced by an electric arc to melt tungsten alloys. This method can be conducted in the absence of air, making it suitable for the high-temperature melting of tungsten and its alloys.
Equipment: Arc furnaces (such as vacuum arc furnaces) are used to provide the high temperatures needed.
Advantages: Can generate extremely high temperatures, making it ideal for melting tungsten and its alloys. It can also be conducted in a vacuum or inert gas atmosphere to reduce oxidation.
Laser Melting
Principle: High-energy laser beams concentrate heat on the surface of the tungsten alloy, precisely controlling the laser power to heat the alloy above its melting point.
Equipment: Laser melting equipment is commonly used for small-scale melting or precision processing.
Advantages: High precision, suitable for localized melting.
Induction Heating Melting
Principle: Electromagnetic induction is used to heat the tungsten alloy to its melting point. Induction furnaces generate eddy currents in the alloy through high-frequency currents, rapidly heating the metal to the melting temperature.
Equipment: High-frequency induction furnaces.
Advantages: Quick heating, precise control of the heating process, and it can be performed in an inert gas environment to prevent oxidation.
Hydrogen Reduction Method
Principle: Hydrogen gas is used in combination with high temperatures to reduce tungsten oxides to metallic tungsten. After reduction, the alloy is further heated to melt it.
Equipment: Hydrogen reduction furnaces.
Advantages: Suitable for reducing tungsten oxides and melting tungsten alloys, ideal for processing tungsten alloys.
Resistive Heating Method
Principle: Direct electrical current is passed through the tungsten alloy, causing it to heat up due to electrical resistance. Due to tungsten’s high resistivity, this method requires high-power currents.
Equipment: Resistance furnaces.
Advantages: Suitable for small-scale melting, relatively simple operation.
Vacuum Melting
Principle: Tungsten alloys are heated in a vacuum environment to their melting point to avoid oxidation and other chemical reactions.
Equipment: Vacuum arc furnaces or vacuum induction furnaces.
Advantages: Ideal for processing high-purity tungsten alloys in a vacuum environment to avoid oxidation or contamination.
Considerations During Melting:
Temperature Control: Given tungsten’s extremely high melting point, strict temperature control is necessary to ensure the alloy melts completely without oxidation.
Inert Gas Protection: Inert gases such as argon or helium are often used during the melting process to prevent tungsten alloys from reacting with oxygen in the air at high temperatures.
Equipment Durability: High-temperature equipment must be made from heat-resistant materials to withstand the extreme temperatures during tungsten alloy melting.
In summary, melting tungsten alloys requires special equipment and conditions, often utilizing high-temperature arc melting, laser, or induction heating technologies, along with inert gas protection to prevent oxidation and ensure successful melting.
