Grain Size Influence on Microwave Absorption Properties in Nanocrystalline Fe40Co60

Abstract

The work we have undertaken consists of preparing nanocrystalline Fe40Co60 powders by the Mechanical Alloying (MA) route. Characterization of obtained powders was applied on two steps. First, structural properties were investigated. X-ray Diffraction (XRD) was used to identify the formation of a disordered α (Fe40Co60) solid solution with a bcc lattice after 60h milling. By the Halder-Wagner approach lattice size, average grain size and residual strain were fixed. The morphology of milled powders was investigated by Scanning Electron Microscopy (SEM). Then bulk specimens were prepared by cold compaction for microwave measurements. Microwave dielectric permittivity and conductivity were determined using cavity perturbation technique. Microwave absorbing characteristic was measured according to line transmission method. Results obtained confirm that the developed structure after milling is the main factor that influences the microwave properties of nanocrystalline Fe40Co60 powders compared to elemental Fe.