Effects Of Alloying Elements On The Cu/?-Fe Interfacial Properties:A First-principles Study

Deformation processed Cu-Fe in situ composites is an unlimited potential copper alloy,which has the advantage of wide raw material sources,low cost of iron,theoretical high-strength and high-conductivity property.However,due to the relatively higher solubility of Fe in the Cu matrix at high temperature and slow kinetics of Fe precipitation,the dissolved Fe induce strong impurty scattering and reduce the electrical conductivity of Cu severely.Therefore,accelerating the precipitation of Fe has become the key to improving properties of Cu-Fe alloy.Adding a third alloying element is a possible way to reduce the solubility of Fe in copper alloy.However,the selection of appropriate alloy elements in Cu-Fe alloy remains to be solved.In this thesis,the work of adhesion,interfacial energy,lattice misfits and electronic structure are calculated by first-principles calculations based on density functional theory.The effects and mechanisms of alloying elements on Cu/?-Fe interfacial properties are studied to provide theoretical basis for the selection of alloy elements.The main details and results of the research are listed below:(1)The most favorable sites of alloying atoms in the interface region were analyzed.All elements are inclined to soluble in Cu matrix.Mg,Ag and Cd are located at farthest site and next nearest neighbor site separately because of the exclusion of ?-Fe,while other eleven elements are located at the nearest neighbor sites.(2)The effects of alloying elements on the Cu/?-Fe interfacial properties were studied.The alloying elements B,Si,P,Al and Zr can improve the stability of Cu/?-Fe interface by increasing the work of adhesion,while B,Si,P etc.reduce interfacial energy,which is beneficial to the nucleation of ?-Fe.Therefore,B,Si,P,Al and Zr may accelerate the precipitation and form stable ?-Fe phase.(3)The working mechanisms of alloying elements were revealed.The work of adhesion is in inverse proportion to the solute volume of alloy element,while interfacial energy determined by lattice misfit and atomic bonding strength of Cu/?-Fe interface.Therefore,alloy elements which have smaller solute volume and stronger atomic bonding strength can accelerate the precipitation of ?-Fe from Cu matrix by increase the work of adhesion and reduce interfacial energy.