| Copper and copper alloy is one of the earliest metal materials found and used by human beings.It is an indispensable resource in people's production and life,and has important application value in national economy and national defense construction.With the continuous progress of science and technology,the continuous development of new industries,the demand for copper alloy properties and output is also increasing.High strength conductive copper alloy is a kind of high performance copper alloy that has strength far higher than pure copper and excellent electronic conductivity.With the rapid development of electronic information,rail transportation,national defense industry and other fields,as a matter of great importance functional materials,high strength conductive copper alloys are being more and more widely used.Thus,it is of great significance to develop a new type of high strength conductive copper alloy material.The preparation methods of high strength conductive copper alloy mainly include alloying method and composite material method,which means intrducing the alloying elements and reinforced particles or fibers into copper matrix,and then by a series means of controlling the solidification microstructure,deformation,heat treatment and other method to improve the strength of the copper alloy as much as possible,and also maintain the electrical conductivity.This paper proposes a new type of copper alloy,Cu-Mg-Te,through adding Mg and Te element to improve the mechanical performance and the anti arc impact ability of copper alloy,respectively.The comprehensive properties of Cu-Mg-Te alloy are further improved from the point of micro-alloying effect of rare earth elements.The effect of the strengthening mechanism of the main adding element,micro-alloying effect of rare earth element,solidification microstructure control by using electro-magenetic and ultrasonic field,deformation and heat treatment,on the microstructure and performance of the copper alloy were analyzed in this paper.In this paper,the mechanism element Mg and Te and the influence of content of element Mg and Te in copper alloy on the mechanical and electrical properties of Cu-Mg-Te alloy are studied.Element Mg plays a role of solid solution strengthening in the alloy.In conclusion,through experimental comparison and analysis,when the content of Mg is 0.2?0.7%,the as cast Cu-Mg-Te alloy has good mechanical and electrical properties.The effect of Te addition on the electrical conductivity and mechanical properties of the alloy is not obvious.The arc voltage of alloy is raised and the arc erosion resistance of alloy is improved because of the reduction of the valence electron density through adding element Te with low boiling point.When the content of Te is too high,it will affect the subsequent deformation treatment of the alloy.Therefore,the reasonable Te content should be controlled between 0.1-0.4%.The properties of Cu-Mg-Te alloy are improved by adding microalloying elements such as rare earth Y,Ce and B,because these microalloying elements can preferentially react with oxygen and other harmful impurities in the molten alloy,also simultaneously increase the nucleation number in the molten,which will result in molten purification and grain refining.When the Y is lower than 0.06%and the B is lower than 0.03%,the grain size of the alloy can be reduced to 150?m,the tensile strength,elongation,conductivity and other indicators of the alloy have also been improved.The effect of rare earth Ce on the microstructure refinement of Cu-Mg-Te alloy is very obvious.The properties of the alloy are further improved by rolling deformation and annealing treatment.After hot rolling with 70%deformation,the grain size decreases to 90?m,and meanwhile,the tensile strength and elongation are significantly improved.With the increase of the subsequent cold rolling deformation,because of the obvious work hardening,the tensile strength of the alloy gradually increases,but the elongation decreases.When the cold rolling deformation is 90%,the tensile strength of the Cu-0.52Mg-0.18Te-0.04Y alloy reaches 620MPa,the electrical conductivity is 55%IACS.Annealing treatment leads to a decrease in tensile strength,but elongation and conductivity increase significantly.By reasonably controlling the temperature and time of annealing treatment,the alloy being at the recovery stage has good comprehensive properties.The Cu-0.52Mg-0.18Te-0.04Y alloy was deformed by 70%hot rolling and 90%cold rolling,and annealed at 350 for 1h,the conductivity of the alloy was close to 60%IACS,the elongation was restored to 8%,and the tensile strength reached 560MPa.Electromagnetic field can effectively improve the internal quality of Cu-Mg-Te-Y alloy ingot.The internal microstruce of electromagnetic continuous casting of Cu-Mg-Te-Y alloy is very compact,and the defects like porosity can be effectively removed.Electromagnetic field can expand the area of equiaxed zone,refine grain size obviously,basically eliminate the segregation of Mg element in Cu-Mg-Te-Y alloy,making the Cu2Te phase smaller and more uniform,and significantly reduce the content of oxide impurities in the alloy.Compared with common continuous casting ingot,with the same conductivity,the tensile strength and elongation of electro-magnetic continuous casting Cu-Mg-Te-Y alloy increases by 26.3%and 13%,respectively.After the susquent 70%cold rolling deformation,the tensile strength and elongation of the electro-magnetic continuous casting ingot reaches 480MPa and 14%,respectively.The Cu-Mg-Te-Y alloy treated by the power ultrasonic field during the solidification process can obviously refine the microstructure and improve the element distribution.After 300W,120s ultrasonic vibration treatment,the grain size of the alloy decreases from centimeter to 100?m,and the distribution of element Mg and Te is more uniform,which can effectively reduce the defects such as slag inclusion,porosity and crack in the alloy.The tensile strength of Cu-Mg-Te-Y alloy treated by ultrasonic vibration increases from 151.3MPa to 197.4MPa,and the elongation from 17%to 24.7%.After directly cold rolled with 70%deformation,the tensile strength of Cu-0.38Mg-0.13Te-0.05Y alloy is 465.8MPa,elongation 17%and electrical conductivity 62.6%IACS.The results show that Cu-Mg-Te alloy obtained by electro-magnetic continuous casting and power ultrasonic vibration process can be directly cold deformed,the performance of which is quite consistent with the conventional continuous casting Cu-Mg-Te alloy after two times rolling deformation namely hot rolled and cold rolled.Therefore,the application of electro-magnetic field and ultrasonic field in the actual production of copper alloy can simplify the production process and decrease the product cost. |
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