Why can hard alloys withstand high temperature and high pressure？

Hard alloys, often referred to as cemented carbides or tungsten carbide (WC) alloys, are known for their exceptional hardness, strength, and resistance to high temperatures and pressures. The key factors contributing to the ability of hard alloys to withstand high temperatures and high pressures include:

1. Composition:

Hard alloys are typically composed of tungsten carbide (WC) grains embedded in a metal binder, commonly cobalt (Co). Tungsten carbide is extremely hard and has a high melting point, contributing to the material's ability to withstand high temperatures.

2. Hardness:

Tungsten carbide is one of the hardest materials known, second only to diamond. The hardness of hard alloys arises from the strong covalent bonds between tungsten and carbon atoms. This hardness allows the material to resist wear, abrasion, and deformation even in high-pressure and high-temperature environments.

3. High Melting Point:

Tungsten, the primary component of tungsten carbide, has a very high melting point of around 3,422 degrees Celsius (6,192 degrees Fahrenheit). This high melting point makes hard alloys suitable for applications where extreme temperatures are encountered.

4. Thermal Stability:

Hard alloys exhibit good thermal stability, meaning they can maintain their hardness and mechanical properties at elevated temperatures. This is essential in applications where temperatures can reach levels that would compromise the performance of other materials.

5. Strength and Toughness:

The combination of tungsten carbide grains and the metal binder (cobalt) provides a balance of strength and toughness. While tungsten carbide is extremely hard, the cobalt binder adds toughness and ductility to the material, allowing it to withstand both high pressures and shock loads.

6. Resistance to Deformation:

The hardness and high compressive strength of hard alloys make them resistant to plastic deformation, even under high-pressure conditions. This resistance to deformation contributes to the material's durability in challenging environments.

7. Chemical Inertness:

Tungsten carbide is chemically inert and does not react with many substances at high temperatures. This property enhances the material's stability and resistance to corrosion, oxidation, and chemical degradation.

8. Wear Resistance:

Hard alloys are renowned for their exceptional wear resistance, making them suitable for applications where materials are subjected to abrasive wear, friction, and high pressures.

Due to these properties, hard alloys find extensive use in industries such as mining, oil and gas drilling, metalworking, manufacturing, and other applications where high temperatures and pressures are common challenges. The combination of hardness, strength, and other favorable characteristics makes hard alloys a preferred material for demanding environments.