Preparation And Properties Of FeZrB-based Amorphous-nanocrystalline Alloy

Fe-based amorphous and nanocrystalline soft magnetic alloys have more excellent synthetical soft magnetic properties than traditional soft magnetic materials,displaying excellent energy-saving and environmental protection characteristics.It is a basic functional material with market competitive advantages.Remarkably,FeZrB alloys have high saturation magnetization and strong amorphous formation ability,to study them has been considered as one of the important research directions of Fe-based amorphous and nanocrystalline soft magnetic alloys.Changing compositions of the FeZrB alloys can significantly influence the microstructures and the magnetic properties,however,such research works are lacking,which is impossible to guide the composition design of this kind of alloy materials scientifically and pertinently.The crystallization phases of FeZrB alloys were studied by changing the compositions of alloying elements,optimizing heat treatment processes,adding magnetic element Co and nanocrystalline forming element Cu.The effects of the different compositions on the crystallization phases were discussed,and so were the effects of different crystallization phase constitutions on the magnetic properties of the alloys.This work can provide experimental data and theoretical support to effectively design compositions and improve the performance of Fe-based soft magnetic alloy materials,guiding the research and development of these alloys.The main results are as follows:(1)FeZrB alloys with different compositions were prepared by the single-roller rapid quenching technique.The influence of different compositions on the primary crystallization phase constitution and the magnetic properties of FeZrB alloys was studied.Results show that different compositions could lead to different primary crystallization phases.Four groups of primary crystallization phases are observed in the alloys with different compositions,i.e.?-Fe phase,?-Fe+Fe₁₂Si₂ZrB phases,?-Fe+?-Mn phases,and?-Fe+Fe₂B+ZrB phases,wherein,Fe₁₂Si₂ZrB phase and?-Mn phase are metastable.The saturation magnetization(M_s)and coercivity(H_c)of FeZrB alloys with different primary crystallization phases show the relationship as follows:M_{s(?-Fe phase)}>M_{s(?-Fe+?-Mn type) phases}>Ms(?-Fe+Fe2B+ZrB phases)>Ms(?-Fe+Fe12Si2ZrB type phases);Hc(?-Fe+?-Mn type phases)>Hc(?-Fe+Fe2B+ZrB phases)>Hc(?-Fe+Fe₁₂Si₂ZrB type phases)>Hc(?-Fe phase).(2)Fe₈₄Zr₇B₉,Fe₇₈Zr₇B₁₅and Fe₈₁Zr₉B₁₀alloys with different primary crystallization phases(?-Fe phase,?-Fe+Fe₁₂Si₂ZrB phases and?-Fe+?-Mn phases)were further studied.The effects of different heat treatment conditions[temperature(T_a),holding time and heating rate]on microstructures and magnetic properties of these three alloys were also studied.These three alloys have different crystallization processes.Different crystallization phases lead to different trends of M_sand H_c.Different heating rates and holding time also have different effects on the phase constitutions and magnetic properties of these three alloys.The features of primary crystallization phases in each alloy are the most obvious at the heating rate of 20 K/min and the holding time of 40 min.(3)Based on Fe₈₄Zr₇B₉,Fe₇₈Zr₇B₁₅and Fe₈₁Zr₉B₁₀alloys,[(Fe_1-xCo_x)₈₄Zr₇B₉,(Fe_1-xCo_x)₇₈Zr₇B₁₅and(Fe_1-xCo_x)₈₁Zr₉B₁₀](x=1/6,1/3,1/2)amorphous alloys were prepared by replacing Fe element with different amounts of Co element.The nanocrystalline alloys were prepared by being heat treated at different temperature with the heating rate of 20K/min and the hold time of 40 min,the effects of different Co content on the crystallization and magnetic properties of FeZrB alloys were investigated.For the Fe₈₄Zr₇B₉alloy,the increasing Co content mainly affects the high-temperature crystallization phases of the alloys;for the Fe₇₈Zr₇B₁₅and Fe₈₁Zr₉B₁₀alloys,the increasing Co content significantly changes the crystallization process.The primary crystallization phase in low Co content alloys is?-Fe(Co)phase,and that in high Co content alloys consists of the metastable?-Mn phase and?-Fe(Co)phase.The disappearance of the?-Mn phase in the alloys heat treated at higher temperatures is beneficial to obtain low H_cat higher temperatures.(4)Fe₈₄Zr₇B₉Cu₁,Fe₇₈Zr₇B₁₅Cu₁and Fe₈₁Zr₉B₁₀Cu₁amorphous alloys were prepared by adding 1 at.%Cu element into Fe₈₄Zr₇B₉,Fe₇₈Zr₇B₁₅and Fe₈₁Zr₉B₁₀alloys,respectively.The nanocrystalline alloys were prepared by being heat treated at different temperatures with the heating rate of 20 K/min and the hold time of 40 min.The effect of the Cu element on the microstructures and properties of the alloys was studied.The addition of Cu significantly reduces the thermal stability,simplifies the crystallization process,and inhibits the precipitation of the primary crystalline metastable phase.For the FeZrBCu alloy,different compositions have little effect on the primary crystallization phase constitution.The primary crystallization phases are the same,all of them are single?-Fe phase.While the addition of Cu significantly reduces the H_cof FeZrB alloys and increases the thermal stability of H_cwhen temperature is lower than 923 K.