Fine composite metal particles and magnetic beads

摘要

Fine composite metal particles each comprise a metal core (1) comprising a magnetic metal as a main component and having an average particle size of 10 µm or less, and a multilayer coating (2, 3) of two or more different inorganic materials. Said fine composite particles are formed by the steps of mixing oxide powder of said magnetic metal with at least one of carbon powder and boron-containing powder to provide a mixed powder, and heat-treating the mixed powder in a non-oxidizing atmosphere. An innermost inorganic layer (2) partially or entirely covering said metal core (1) is mainly formed by carbon and/or boron nitride.