Carbide

Carbide (specifically tungsten carbide, in woodworking tools) is an extremely hard, wear-resistant material, brazed as small individual teeth or cutting tips onto a steel blade or bit body rather than forming the whole tool. It holds a working edge dramatically longer than plain high-speed steel, especially cutting abrasive materials like particleboard, MDF, and other resin-bonded sheet goods that dull plain steel edges fast.

The tradeoff is brittleness -- carbide is harder but more prone to chipping on impact than tougher, more flexible steel, which is why carbide-tipped blades and bits need more careful handling (never run into metal, staples, or nails) than an all-steel equivalent would.