【摘要】 研究了低Pt含量的Fe_90-xPt₁₀B_x（x=15～40,原子分数,%）系液态急冷合金热处理前后的组织结构和磁性能。结果表明,x由15增加至25～30可提高合金的非晶形成能力,急冷合金由非晶+fcc-FePt复相组织转变为单一非晶态结构;当x进一步增加至35和40时,合金分别由fcc-FePt+Fe₂B+FeB和L1₀-FePt+FeB纳米复相组织构成。经适当热处理后,x=15～20时的合金具有fcc-FePt+Fe₂B复相组织而呈软磁性;当x=25～40时的合金形成了由有序面心四方结构的永磁L1₀-FePt相和软磁Fe₂B/FeB组成的纳米复相组织,显示出永磁特性,其中x=30的合金经823 K热处理900 s后具有最佳的永磁性能,矫顽力、剩磁和最大磁能积分别为173.2 kA/m,1.20 T和88.3 kJ/m³,其优异的永磁性能源于分布均匀、平均晶粒尺寸约为15 nm的永磁L1₀-FePt相和软磁Fe₂B相间的交换耦合作用。更多还原

【Abstract】 The structure evolution and magnetic properties of melt-spun Fe_90-x Pt₁₀B_x（x=15～40） alloys before and after annealing were investigated.The results show that the increase of x from 15 to 25～30 can improve the amorphous forming ability of the alloy,and the melt-spun structure transforms from a composite composed of amorphous and fcc-FePt phases to a single amorphous phase.Further increasing x to 35 and 40 results in the formation of fcc-FePt+Fe₂B+Fe B and L1₀-FePt+FeB phases,respectively.After appropriate annealing,dual phases of fcc-FePt+Fe₂B are formed for the alloys with x=15～20,which have soft magnetic properties,while the nanocomposite structure consisting of L1₀-FePt together with Fe₂B and/or Fe B phases is obtained for the alloys with x=25～40,which exhibit the characteristics of the nanocomposite magnets.The best permanent magnetic properties are obtained for the alloy with x=30 annealed at 823 K for 900 s,of which the coercivity,remanence and maximum energy product are 173.2 kA/m,1.20 T,and 88.3 kJ/m³,respectively.The good permanent magnetic performance is due to the formation of a more fine and homogeneous L10-FePt/Fe₂B nanocomposite structure with an average grain size of about 15 nm.更多还原