| Fe-based amorphous alloys with unique atomic structure have attracted great attention due to their high strength and hardness,high wear resistance,excellent soft-magnetic properties(SMPs)and corrosion resistance,which are expected to be a novel generation of structural and functional materials.However,the most significant disadvantages of the amorphous alloys are the limitation of amorphous formability,almost zero plastic deformation at room temperature and low saturation magnetic flux density,which seriously restrict their practical applications.Therefore,the exploration of Fe-based amorphous alloys with certain amorphous formability and excellent mechanical,magnetic and chemical properties has become a research topic in the field of contemporary structural and functional materials,which is of great scientific significance and practical value.Up to now,the development of Fe-based amorphous alloys is mainly around the FeB(Si)and FePC systems.The former has large amorphous formability,high strength and hardness,while the latter has good plastic deformation and catalytic degradation ability.Thus,in this work,based on the strategy of endogenous second phase,the plastic deformation and magnetic softness of FeB(Si)-based amorphous alloys are investigated;using magnetic exchange-coupling between elements,the magnetic softness and chemical catalytic properties of FePC-based amorphous alloys are studied.The effect of enhanced plasticity of FeCoBSiNb by controlling the structure heterogeneity with Cu addition,the effects of Co/B addition on the SMPs of FePCCu amorphous/nanocrystalline alloys,and the effect of FeCoPCCu amorphous alloy on the degradation of organic dyes are systematically investigated,respectively,using X-ray diffraction,transmission electron microscopy,scanning electron microscope,differential scanning calorimeter,DC B-H loop tracer,impedance analyzer,vibrating sample magnetometer,testing machine and UV-vis spectrophotometer,etc.Main researchful works include:(1)The effects of Cu addition on amorphous formability,plastic deformation and magnetic softness of FeCoBSiNb amorphous alloys were systematically investigated.It was found that the structural evolution was drastically activated through single phase to multi-phases transition on crystallization behavior with Cu addition,which induced an obvious change of primary crystallization phase from(Fe,Co)23B6 to?-(Fe,Co).With 0.3 at.%Cu addition,the thermal stability and amorphous formability were improved and critical diameter of alloy up to 4 mm,which may be owed to the competition between different primary crystallization phases.Although the magnetic softness of the alloy was slightly decreased due to the Cu addition,the room temperature plastic deformation of alloy distinctly increased from 0.4%to 3.7%with a high strength over 4 GPa.The improved plasticity was strongly related to the nano-scale heterogeneous structure(?-(Fe,Co)clusters)introduced to the glassy alloy by phase separation with minor Cu addition,which can hinder the propagation of shear bands,promote multiple shearing and enhance the plasticity.(2)The effects of Co addition on amorphous formability,thermal stability and magnetic softness of FePCCu amorphous alloys with high Fe content were systematically investigated.It was found that amorphous formability and thermal stability of the alloys can be improved as the precipitation of?-Fe phase during the quenching process was inhibited by substitution of Co for Fe.Meanwhile,the mechanism of enhanced Bs for quenched alloys with Co addition was explored,and the relationship between magnetic properties and magnetic valence was revealed.After crystallization,the FeCoPCCu nanocrystalline alloy exhibited excellent SMPs with saturation magnetization of 1.8 T,coercivity of 6.6 A/m and effective permeability of 15510.The relationship between microstructure and magnetic properties was explored and the main causes of abnormal changes in coercivity before and after Co addition were discussed,which was closely related to the large magnetocrystalline anisotropy constant and weak ferromagnetic exchange-coupling of?-(Fe,Co)grains.(3)The effects of metaloid B element on amorphous formability,thermal stability,SMPs and microstructures of FePCCu alloys were investigated.It was found that the addition of small atom B can promote the formation of densely atomic structure of alloys.The melting and solidification curves revealed the eutectic behavior induced by proper B addition,which promoted the enhancement of amorphous formability.The mechanism of B substitution for P on tuning the magnetic properties of Fe PBCCu amorphous alloys was explored,which was supported by electron transfer theory and experiment.Based on high saturation magnetization amorphous matrix,the Fe PBCCu nanocrystalline alloys with excellent SMPs were developed,and the factors related to SMPs were further explored.The intrinsic relationship between structural heterogeneity and relaxation behaviour of alloys was investigated by thermodynamic behavior,and the origin of the excellent SMPs of nanocrystalline alloys was revealed.(4)The effects of Co addition on decolorization performance of FePCCu amorphous alloy for degrading methylene blue(MB)using Fenton-like reactions were investigated.It was found that amorphous alloy with proper Co addition exhibited excellent dye degradation ability compared to its counterpart,and with excessive Co addition,the alloy showed a good corrosion resistant.The such difference of dye degradation ability caused by Co addition was explored.The effects of MB solution concentration and p H on the degradation efficiency of alloy were studied,and the reusability of FeCoPCCu amorphous alloy for degradation of organic dyes was also explored by the cycle experiments.It was found that Fe79.2Co4P10C6Cu0.8 amorphous alloy exhibited a long service life after 13 degradation cycles(100 mg/L MB solution can be rapidly degraded within 15 min).Such excellent degradation ability and recyclability were mainly attributed to the continuous shedding of the nano-whiskers oxidation layer in the reaction.The“fresh”amorphous surface is in full contact with MB solution to ensure the continuous Fenton-like reaction. |
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