Addition method of grain growth inhibitor used for preparation of ultrafine hard alloy

The invention relates to an addition method of a grain growth inhibitor used for the preparation of ultrafine hard alloy. The method comprises the following steps: designing components of Co-based alloy powder; preparing Co-based alloy powder containing the grain growth inhibitor by adopting a coprecipitation process; and weighing corresponding tungsten carbide powder and the Co-based alloy powder according to formula proportions, mixing, adding a wet grinding medium, carrying out wet grinding to make the surface of particles of the tungsten carbide powder uniformly coated by the Co-based alloy powder containing the grain growth inhibitor. The invention also discloses an ultrafine hard alloy with the crystal grain size below submicron (including but not limited to a nanometer level range). The carbonization temperature of the ultrafine hard alloy is not limited by Co, and WC carbonization is complete, so crystal grains are complete, and have few defects.