PREPARATION OF NANOCRYSTALLINE/AMORPHOUS STRUCTURE IN SOFT MAGNETIC FE-BASED ALLOYS BY MECHANICAL ALLOYING

摘要

Iron-based soft magnetic alloys were prepared by mechanical alloying method in planetary ball mill from pure elemental powder. Phase conditions and morphology of as-milled powders were investigated by means of XRD and SEM/EDX. Also, grain size as function of milling time was estimated by using XRD and TEM methods. Thermal stability and phase conditions after heating were studied using DTA and XRD. Mechanical alloying of soft magnetic Fe-based alloys led to the formation of supersaturated solid solution, multiphase or possibly amorphous structure. The solid solution and amorphous phases were quite homogeneous. As function of milling time, grain refinement can be described by the equation D=Ct~n with n ranging between -0.30 to -0.45. The transformation temperature depends on alloying elements and lies in range 900-1000K for solid solution structure. Multiphase structures showed lower thermal stability in this respect (700-800K) and crystallised in steps with forming of complicated boride phase mixture and some intermetallic phases.