Structure and hyperfine interactions of mechanically synthesized Co-Fe-Ni alloys

摘要

Mechanical alloying method was applied to prepare Co_(50)Fe_(40)Ni_(10), Co_(40)Fe_(40)Ni_(20), Co_(50)Fe_(35)Ni_(15) and Co_(60)Fe_(30)Ni_(10) alloys. X-ray diffraction and M6ssbauer spectroscopy were used as complementary methods to obtain structural and hyperfine interactions data of the as-milled samples. X-ray diffraction proved that during mechanical alloying process the solid solutions with b.c.c. lattice were obtained in the case of Co_(50)Fe_(40)Ni_(10), Co_(50)Fe_(35)Ni_(15) and Co_(60)Fe_(30)Ni_(10) alloys, while for Co_(40)Fe_(40)Ni_(20) composition the solid solution with f.c.c. lattice was formed. Result obtained for Co_(50)Fe_(40)Ni_(10) alloy is consistent with the phase diagram for the Co-Fe-Ni bulk alloys prepared by melting. On the other hand, the milling process of Co_(40)Fe_(40)Ni_(20), Co_(50)Fe_(35)Ni_(15) and Co_(60)Fe_(30)Ni_(10) alloys resulted in the formation of the single solid solution, while for these chemical concentrations the melted alloys are a mixture of b.c.c + f.c.c. phases. Mossbauer spectroscopy revealed hyperfine magnetic field distributions, which reflected the different surroundings of ~(57)Fe isotopes by Co, Fe and Ni atoms, depending on the chemical composition of the alloy. The most probable atomic configurations were determined on the basis of the local environment model.