| Recently,with the rapid development of precision electronics technologies,the demand for thin and light magnetic shielding materials is growing quickly.The 50%Ni-Fe alloy foil is an excellent soft magnetic material and has the superior magnetic shielding performance,which can be used as core of transformer and sensor.It also has the great potential for applications in ultra-thin electronic components and buzzer diaphragm.Up to now,the electrodeposition is well known as a technological and economical method,capable of producing large scale and high purity nanocrystalline metals in one step.And the cost reduces as the thickness of product decreases.Therefore,the electrodeposition method has been attracting more and more attention.However,the magnetic properties of electrodeposited Fe-Ni alloy are lower than that of the rolled Fe-Ni alloy after heat treatment,which limits the practical application of these materials.In this work,in order to expand the application range of the electrodeposited Fe-Ni alloy foil,the magnetic properties and mechanical properties of electrodeposited Fe-Ni alloy foil were improved by high-temperature heat treatment.The evolution in microstructure and texture of the electrodeposited Ni-Fe alloy foil were also studied after heat treatment.To solve the sticking problem,the sticking mechanism and associated control method were studied.The sticking could be hindered by coatings of MgO on the surface of the alloy foils through electrophoretic deposition.The results presented in this work will provided a reference for industrial appications.Firstly,the microstructure of electrodeposited Fe-Ni alloy was studied.Based on fully understanding of its basic characteristics,heat treatment experiments were carried out under different heat treatment conditions by using high-temperature tube furnace.SEM and XRD were used to study the effect of heat treatment on the microstructure of electrodeposited Fe-Ni alloy.The results showed that the grain size of the electrodeposited Fe-Ni alloy increased from nano-scale to micro-scale level,and the average grain size increased with increasing annealing temperature and holding time.In order to deeply understand the microstructure evolution of electrodeposited Fe-Ni alloy during annealing,the grain growth was in situ online investigated using a heating stage microscope.The various alloy foil microstructures observed in this study underwent three stages as the annealing temperature and holding time increased,i.e.,fine-grain microstructure,mixed-grain microstructure,and coarse-grain microstructure.Because the grain orientation had great influence on the magnetic properties,the grain orientation was analyzed by EBSD technique.The results showed that the {111} texture of the alloy foil was preferred with the increase of annealing temperature and holding time.Secondly,the soft magnetic DC magnetic measurement system(NIM-2000S)was used to study magnetic properties.The effect of recrystallized microstructure on magnetic properties was studied.The results showed that the magnetic property was improved after heat treatment,but the saturation magnetic induction intensity changed little after heat treatment.Since the magnetic properties could be further improved by the texture optimization,the method of controlling the texture of electrodeposited Fe-Ni alloy foil was studied.The results showed that the {110}texture can be obtained by a rapid heating treatment.The electrodeposited of Fe-Ni alloy with {100} texture can be obtained by electrodeposition on the basis of(100)oriented single crystal copper.In addition,in order to expand the application range of the electrodeposited Fe-Ni alloy foil,the mechanical properties of the foil were studied after heat treatment.The results indicated that the annealed electrodeposited Fe-Ni alloy foil had good plasticity and was easy to be processed.Due to the compact microstructure of the alloy after heat treatment,the microstructure defects of the original electrodeposited Fe-Ni alloy foil were eliminated,and the elastic modulus was increased by 30%.It can meet the requirement of the elastic modulus of diaphragm material.Finally,the sticking phenomenon occurred easily during heating treatment of electrodeposited Fe-Ni alloy foil.To solve the sticking problem,sticking mechanism was studied.The results indicated that the formation and growth of the symbiotic grains at the interface of the alloy foils leaded to sticking phenomenon.On this basis,the methods of inhibiting electrodeposited Fe-Ni alloy foil during annealing at high temperature were studied.The results indicated that the MgO coating with good surface quality can be obtained after electrophoretic deposition. |
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