Amorphization of ErFe2 obtained by milling under different atmospheres

In the present work, high-energy milling under two different atmospheres wa s applied to the ErFe2 intermetallic compound and to the chemical elemental powders of Er and Fe with ErFe2 stoichiometric composition. Sample A is th e compound milled under Ar, sample B the compound milled under N-2 and samp le C the elemental powders milled under N-2 atmosphere. X-ray diffraction ( XRD) and Mossbauer spectroscopy (MS) results of the samples A and B show a segregation process with increase of the milling time. Under N-2 atmosphere , the initial compound was nearly dissociated with 50 h of milling, while w ith Ar atmosphere the segregation process was completed with 100 h of milli ng. From the analysis of the XRD and MS results, it was possible to observe the appearance of other phases at intermediate milling times, in both samp les A and B. One phase was associated with an amorphous ErFe2 alloy with a magnetic ordering temperature, obtained by AC magnetic susceptibility, at a bout 190 K, a second phase was attributed to nanocrystallites of alpha-Fe a nd a third one associated with an fee Er high-pressure phase stabilized by N atoms. In the case of sample B, for milling times longer than 400 h, XRD and MS results indicate the presence of an Fe-Er-N disordered alloy, with m agnetic ordering temperature above room temperature. The XRD and MS results of sample C show the formation of an ErFe2 amorphous phase, with about 87% of MS relative area in this phase at 68 h of milling.