Alloy powder, nanocrystalline powder and magnetic core

An alloy powder comprising particles, wherein:

• the particles include specific particles;
• each of the specific particles has a surface layer on which a divided trace is formed, the divided trace being a mark at which molten alloy is divided;
• the divided trace has at least a hill-like ridge aggregate structure or a combination of a crater structure and the hill-like ridge aggregate structure, the hill-like ridge aggregate structure being an aggregate of a plurality of hill-like ridges;
• each of the specific particles has an oxide layer located under the surface layer;
• the oxide layer located just under the divided trace has a thickness that is thicker than a thickness of the oxide layer located not just under the divided trace;
• the oxide layer located just under the divided trace has a thickness of 30 nm or more;
• and
• each of the specific particles has a sphere shape formed with the divided trace.