Cobalt-based alloy powder

Cobalt-based alloy powder
Cobalt-based alloys are formed by incorporating an appropriate amount of tungsten and carbon into a cobalt-chromium alloy. The addition of tungsten further strengthens the cobalt matrix through solid solution strengthening. Carbon has very low solubility in cobalt, so the added carbon and excess tungsten form carbides such as W, W₂C, and M₆C. These hard phases are dispersed throughout the cobalt matrix, resulting in precipitation strengthening. This enables the alloy to maintain excellent high-temperature strength and hardness even at 800°C. As a result, cobalt-chromium-tungsten-carbon alloys exhibit outstanding comprehensive properties, including high-temperature wear resistance, high-temperature oxidation resistance, and thermal fatigue resistance. At temperatures below 417°C, cobalt has a hexagonal close-packed (HCP) structure with a low coefficient of friction, contributing to its excellent wear resistance. At 417°C, a phase transformation occurs from the hexagonal close-packed lattice to a face-centered cubic (FCC) lattice, generating volumetric stress. Therefore, during surfacing or spray welding, the workpiece is generally preheated to 500°C–600°C to prevent cracking in the cobalt-based weld layer. Examples include CoCrMo, CoCrMoW, Co01, Co06, Co12, Co21, and others.