The reason why cemented carbide is brittle is due to the characteristics of its internal structure.

Tungsten carbide is usually made from a mixture of metal (such as cobalt、nickle,usually we called binders) and one or more carbides (such as tungsten carbide). The particles of these carbides are evenly distributed in the metal matrix, forming a structure similar to ceramics. This structure has the characteristics of high hardness, high wear resistance and high corrosion resistance, so it is widely used in the manufacture of tools, bearings and abrasives.

However, the ceramic structure of cemented carbide also makes it prone to fracture. Under the action of external force, the particles inside the cemented carbide are prone to shear deformation, resulting in internal stress concentration. If the stress concentration exceeds the strength limit of cemented carbide, cracks will occur and eventually lead to fracture.

Therefore, cemented carbide is brittle and prone to fracture. In order to reduce brittleness, measures such as controlling particle size and distribution, increasing the toughness of the metal matrix, etc. can be adopted.