| Abstract: | A nanoporous FePt alloy has been fabricated by dealloying a melt-spun Fe_(60)Pt_(20)B_(20) alloy composed of nanoscale amorphous and face-centered-cubic FePt(fcc-FePt) phases in H_2 SO_4 aqueous solution.The nanoporous alloy consists of single fcc-FePt phase with an Fe/Pt atomic ratio of about 55.3/44.7,and possesses a uniform interpenetrating ligament-channel structure with average ligament and pore sizes of 27 nm and 12 nm,respectively.The nanoporous fcc-FePt alloy shows soft magnetic characteristics with a saturation magnetization of 37.9 emu/g and better electrocatalytic activity for methanol oxidation than commercial Pt/C in acidic environment.The phase transformation from disordered fcc-Fe Pt into ordered face-centered-tetragonal FePt(L1_0-FePt) in the nanoporous alloy has been realized after annealing at823-943 K for 600 s.The volume fraction of the L1_0-FePt phase in the alloy increases with the rise of annealing temperature,which results in the enhancements of coercivity and saturation magnetization from 0.14 kOe and 38.5 emu/g to 8.42 kOe and 51.4 emu/g,respectively.The ligament size of the samples is increased after annealing. |
