Fe_(50)Ni_(50) synthesized by high energy ball milling: A systematic study using X-ray diffraction, EXAFS and Mossbauer methods

摘要

Fe_(50)Ni_(50) alloy powder was prepared by milling the 1:1 stoichiometric mixture of Fe and Ni high purity elements using high energy vibrational ball-mill. Final powdered material was obtained directly after 30 h of milling process and the Rietveld analysis of the X-ray diffraction pattern of the sample reveals the presence of two Fe-Ni phases: the disordered y-(Fe(45)Ni_(55)) alloy, with 91% of total fraction of the material (Fe-Ni solid solution plus grain boundary regions) and the chemically-ordered FeNi phase (9%), with L1_0 tetragonal structure. Average grain sizes of these Fe-Ni phases are respectively 60 nm and 20 nm. Results of extended X-ray absorption fine structure of Ni and Fe as well as ~(57)Fe Mossbauer spectroscopy also suggest the presence of atomically ordered FeNi phase. Mossbauer data have also shown that both Fe-Ni phases are magnetically ordered at room temperature. Our results indicate that high energy milling method can simulate extreme conditions of sample preparation required for the formation of the T-FeNi phase.