PURPOSE: To obtain the titled particles suitable for removing burr of mechanical parts, etc., by blending aluminum and iron oxide powder as raw materials in a ratio of three phase coexistence range of corundum phase alumina, α phase iron and iron alumina spinel and in specific ratio of iron and alumina and subjecting the blend to solid-phase exothermic reaction.

CONSTITUTION: Aluminum and iron oxide powder as raw materials are blended in a ratio capable of forming three phase coexistence range of corundum phase alumina, αphase iron and alumina spinel, the amount of iron is ≥48wt% and that of Aluminum is ≥11wt%, the blend is molded or put in a container having one open end, one end of the molded article or the container is heated in an inert gas atmosphere, a solid- phase exothermic reaction is started, the reaction is propagated successively in a layer state with the reaction heat, the prepared solid reaction product is ground to give the aimed particles which have three phases of corundum phase alumina, α phase iron and iron aluminum spinel detected by X-ray diffraction method, and have ≥48wt% iron and ≥11wt% aluminum and preferably ≤44μm particle diameter.

EFFECT: Having improve efficiency of magnetic abrasion method and improved economic efficiency.