Research On The Preparation And Properties Of FePCu Nanocrystalline Soft Magnetic Alloys

Fe-based nanocrystalline soft magnetic alloys have both high magnetic flux density which istypical characteristic of traditional soft magnetic materials and high permeability and low coercivityof amorphous alloys. It has been a hot topic in both academia and industry since its advent. In recentyears researchers have devoted themselves to developing new alloys without expensive earlytransition metal elements such as Nb, Zr et al in order to decrease the cost of nanocrystalline softmagnetic alloys.In this thesis we make full use of the good glass forming ability (GFA) near the eutecticcomposition of Fe-P binary phase diagram to fabricate Fe83P16Cu1ternary amorphous ribbon. And softmagnetic properties, thermal stability and crystallization kinetics of the amorphous alloy as well as thechange of magnetic properties during the annealing process are investigated. Melt-spun Fe83P16Cu1amorphous alloy ribbons have low thermal stability whose crystallization activation energy of α-Fephase is238kJ/mol. The temperature range of crystallization is narrow for Fe83P16Cu1amorphousribbons and the coercivity of the alloy depends strongly on annealing temperature. Fe83P16Cu1nanocrystalline soft magnetic alloy with a grain size around18nm can be obtained after annealing theamorphous alloy at563K for2min, and it shows good soft magnetic properties (coercivity, Hc=8.7A/m, magnetic flux density, B8000=1.65T).In order to widen the range of annealing temperature and improve the antioxidant ability of theFe83P16Cu1alloy the P is partially substituted by Si. For the Fe83P16-xSixCu1alloy appropriate additionof Si is effective to widen the annealing temperature range and decrease the annealing temperaturedependence sensitivity of Hc, thus improving the controllability during crystallization process.However, when the content of Si increases to4at.%there exist crystallized (200) textures of α-Fewhich deteriorate soft magnetic properties of melt-spun ribbons. The activation energy of α-Fe inFe83P13Si3Cu1amorphous alloy is253kJ/mol. And Fe83P13Si3Cu1nanocrystalline soft magnetic alloywith Hc=7.3A/m, B8000=1.58T can be obtained after annealing the amorphous precursor at593K for2min.In order to further decrease the P content of the alloy in this thesis we have tried to substituate P byjointly adding Si and C with the adjust of the Fe content. It reveals that the Fe80P9Si3C7Cu1alloy hasgood GFA and soft magnetic properties. The jointly adding of Si and C further widens the annealingtemperature range and increases the activation energy of crystallization. Fe80P9Si3C7Cu1nanocrystalline alloy ribbons with good soft magnetic properties (Hc=5.9A/m, B8000=1.68T) can be obtained afterannealing the amorphous precursor at653K for2min.The Fe80P9Si3C7Cu1nanocrystalline soft magnetic alloy developed in this thesis has no expensiveearly transition metal and metalloid B, which makes this alloy have low material cost. Moreover,compared with traditional amorphous soft magnetic alloys the amorphous precursor of this alloy hasmuch lower annealing temperature and shorter annealing time, thereby low energy consumption inannealing process. Low production cost and good soft magnetic properties of this alloy promoise itspotential application in the future.