X-ray line profile analysis of the ball-milled Fe–30Co alloy

This work deals with the microstructural properties of the Fe–30Co alloy prepared by ball milling of elemental iron and cobalt powders. The obtained mixed powder has been characterized by means of scanning electron microscope, X-ray microanalysis, laser diffraction, X-ray diffraction and microhardness measurements. X-ray line profile analysis based on the Rietveld method and adopting two different models has been used for the microstructural study. The refinement of the X-ray patterns shows that after 3 h of high energy milling the Fe(Co) is formed. The obtained Fe(Co) solid solution is characterized by body centered cubic structure with a lattice parameter a = 0.28564 ± 0.00004 nm and an ellipsoidal crystallite and microstrain field. The dissolution of cobalt in iron matrix is accompanied by the compression of the crystalline lattice by 0.37%. The progress of milling process produces an increase of the Debye–Waller factor and the dislocation density leading to the hardening of the powder. The variation of microhardness with milling time shows a change in hardening mechanisms.