Study On Optimization Of Co-reduction Process And Microstructure And Properties Of Copper-iron Alloy With High Strength And High Conductivity

With the development of industries such as electronic,automobile,communication and construction,higher requirements have been put forward on the performance of materials,with a high strength and an excellent electrical conductivity simultaneously.Cu-Fe alloy,combining the advantages of good conductivity of Cu and superior strength and hardness of Fe,can be used for the fields of magnetic recording,optical devices,sensors,etc.However,there are still many shortcomings in the fabrication of Cu-Fe alloy.In this study,Cu-Fe alloy was prepared by in-situ symbiotic co-reduction method,in order to solve the issues of segregation,uneven mixing,impurity generating and low efficiency in the traditional fabrication method.The effects of in-situ symbiotic conditions,heat treatment process and Fe contents on the morphology,microstructure and properties of Cu-Fe alloy have been studied.The main research results are as follows:(1)Raw materials of Cu(NO3)2·3H2O and Fe(NO3)3·9H2O,as raw materials,were mixed as the precursors solution,which can be used to obtain Cu(NO3)2/Fe(NO3)3 composite powder by spray-drying.Subsequently,Cu(NO3)2/Fe(NO3)3 composite powder was thermally decomposed and reduced in hydrogen to obtain a Cu-Fe composite powder with uniform particle distribution and excellent bonding.Herein,Cu-Fe composite powder was obtained by spray drying of 10% concentration Cu(NO3)2/Fe(NO3)3 solution at a feed rate of 6 m L/min,decomposition at 450°C,and reduction at 600°C.The particle size was relatively fine and there was no large-scale agglomeration,in which the Cu and Fe has a good bonding.(2)During the heat treatment process,the grain size of Fe particles was increased,and the proportions of impurities,strain were decreased.However,the grain refining strengthening and solid solution strengthening were weakened.With the increase of heat treatment temperature and time,the electrical conductivity,the elongation and the magnetization were gradually increased,whereas the tensile strength,hardness and coercive force were decreased.Among them,the comprehensive properties of tensile strength,hardness,electrical conductivity and magnetic property of Cu-Fe are optimized after heat temperature of 600°C and heat time of 5 h.(3)As the Fe content increases,the probability of Fe phase particles collision and agglomeration was increasesd due to “spherical motion”,resulting into the increased size of Fe phase.Herein,the increase of the Fe phase size can induce an increase in the interfacial repulsive force between the Cu phase and the Fe phase,leading to the refining of the crystal grains.Nevertheless,the strain of Cu-Fe composite powder was increased,which can be attributed to the differences of ductility and thermal expansion coefficient between Cu and Fe phase.On the other hand,when the Fe content was increased from 30% to 70%,the tensile strength,the hardness,the magnetization and the coercivity force were increased by 35%,24%,219%,131%,respectively.However,the elongation and the electrical conductivity were reduced by 43% and 38% respectively.