Hot-press sintering of MA Fe-based nanocrystalline／amorphous soft magnetic powder

Microstructures and magnetic properties of Fe84 Nb7 B9, Fe80 Ti8 B12 and Fe32 Ni36 (Nb/Ⅴ) 7 Si8 B17 powders and their bulk alloys prepared by mechanical alloying(MA) method and hot-press sintering were studied. The results show that: 1) After MA for 20 h, nanocrystalline bcc single phase supersaturated solid solution forms in Fe84-Nb7 B9 and Fe8o Ti8 B12 alloys, amorphous structure forms in Fe32 Ni36 Nb7 Si8 B17 alloy, duplex microstructure composed of nanocrystalline γ-(FeNi) supersaturated solid solution and trace content of Fe2B phase forms in Fe32 Ni36-V7 Si8 B17 alloy. 2) The decomposition process of supersaturated solid solution phases in Fe84 Nb7 B9 and Fe80 Ti8 B12alloys happens at 710 -780 ℃, crystallization reaction in Fe32 Ni36 Nb7 Si8 B17 alloy happens at 530 ℃ (the temperature of peak value) and residual amorphous crystallized further happens at 760 ℃ (the temperature of peak value), phase decomposition process of supersaturated solid solution at 780 ℃ (the temperature of peak value) and crystallization reaction at 431 ℃ (the temperature of peak value) happens in Fe32 Ni36 V7Si8B17 alloy. 3) under 900 ℃, 30 MPa,0.5 h hot-press sintering conditions, bulk alloys with high relative density(94.7%- 95.8%) can be obtained. Except that the grain size of Fe84 Nb7B9 bulk alloy is large, superfine grains (grain size 50 - 200 nm) are obtained in other alloys. Except that single phase microstructure is obtained in Fe80 Ti8B12 bulk alloy, multi-phase microstructures are obtained in other alloys. 4) The magnetic properties of Fe80 Ti8 B12 bulk alloy(Bs = 1.74 T, Hc = 4.35 kA/m) are significantly superior to those of other bulk alloys, which is related to the different phases of nanocrystalline or amorphous powder formed during hot-press sintering process and grain size.

Hot-press sintering of MA Fe-based nanocrystalline/amorphous soft magnetic powder