Influence Of Magnetic Field On Structure And Property Of Cu-Fe Alloy With Different Composition

High-strength, high-conductivity Cu-based alloys have excellent physical and mechanical properties. And they have potential applications as the high pulsed magnetic field conductors, lead frames and other devices. Especially, Cu-Fe systems have been widely attracted since their strengths are significantly increased by the addition of Fe and the cost of Fe is lower. Controlling and optimizing solidified structure of Cu-Fe alloys and raising the combination property are concerned in the investigations on Cu-Fe composites. In this thesis, the influence of vertical and horizontal magnetic field on the solidification microstructure of Cu-Fe alloys is investigated. Further, these solidified Cu-Fe alloys are drawn to form in-situ deformed Cu-Fe composite by many passes drawing. Effect of Fe percent and magnetic field on the evolution of the microstructure, mechanical propertis and conductivity is presented. The followings are the results.1) With the increasing of Fe weight percent, the morphology of Fe-rich phases is transformed from the spherical pattern to dendritical pattern in the microstructure of Cu-Fe alloys. When imposed by the vertical and horizontal magnetic field, the distribution of the phase in the Cu-Fe alloys is more homogenous.2) With the increasing of imposed magnetic field strength, the relative strength in the (111) crystal plane of Cu for Cu-Fe alloys strengthens, which indicates that the preferred growth of (111) crystal plane is enhanced by imposition of magnetic field. The analysis of EDX shows that Fe contents in the Fe dendrites decrease with the increase of magnetic flux density and its distribution is more homogeneous. Further more, the analysis on micro-hardness of Cu-Fe alloys indicates the micro-hardness is increased by imposed by magnetic field.3) After many passes drawing, the Fe-rich phase in Cu-Fe alloys solidified with and without magnetic field are both gradually elongated and refined with the increasement of drawing ratio. In the range of the lower drawing ratio, the tensile strength of Cu-Fe composites is almost satisfied with the rule of mixture. 4) With the increasing of Fe weight percent, the tensile strength of Cu-Fe composites increases. At the fixed drawing ratio, the strengths of Cu-Fe alloys solidified with magnetic field are lower than the ones of Cu-Fe composites solidified without magnetic field. However, the increasement extent of the tensile strength increases when imposed by magnetic field. While the Fe percent is up to 12%, the strength is almost same with and without magnetic field.5) With the increasing of Fe weight percent, the electrical conductivity of Cu-Fe composites rapidly increases firstly, and then stabilizes at the value of 30%IACS. The effect of magnetic field on the conductivity of Cu-Fe composites is smaller.