| Cu-Ti alloy is a typical age hardening high strength and high elasticity alloy.Under the current environment-friendly research requirements,it is considered to be a promising alternative to the traditional Cu-Be alloy and widely studied.Among them,Cu-2Ti and Cu-3Ti alloys are widely used because of their balanced properties.However,even after heat treatment and work hardening,there is still a certain gap between the properties of Cu-Ti binary alloy and that of Cu-Be alloy.It is found that alloying elements such as Sn,Cd,Zr,Mg,Fe,Cr can be used to strengthen Cu-Ti alloy,so as to improve and optimize the properties of the alloy.In this paper,Cu-3Ti is taken as the research object.By studying the aging characteristics of the alloy at different temperatures,the discontinuous precipitation kinetics of the alloy at different temperatures is analyzed and calculated to determine the best aging process of the alloy.In addition,the effect of Cr on the structure,properties and aging behavior of the alloy was studied by adding Cr,and the effect of different aging temperature on the discontinuous precipitation kinetics of deformed Cu-Ti(Cr)alloy was also studied.The main research contents and conclusions are as follows:(1)The cu-3ti alloy was prepared by vacuum melting.The aging temperature of 400 ?,450 ?,500 ? and 550 ? was selected to age the alloy.The aging time was 0-96 h respectively.It was found that the peak aging time of the alloy could not be controlled precisely because it was too fast under the aging temperature of 550 ?,which easily resulted in the alloy not reaching or entering the over aging stage,At a low aging temperature of 400 ?,the peak aging time of the alloy is about 72 hours.Therefore,the best aging temperature of cu-3ti alloy is 500 ? and 450 ? according to the difficulty of experimental operation and the prospect of industrial application.In addition,it was found that the peak hardness of the alloy aged at 450 ? was higher than 500 ? in the same aging time,and there was no significant difference between the conductivity of the alloy aged at 450 ?,so 450 ? was the best aging temperature for cu-3ti alloy.(2)The aging kinetics of discontinuous precipitation in cu-3ti alloy was calculated.It was found that the n value decreased with the increase of aging temperature,which indicated that the nucleation site of discontinuous precipitation changed from grain intersection to grain intersection,and the K value increased with the increase of temperature.The activation energy of the discontinuous precipitation is 35 kJ / mol,which indicates that the growth of the discontinuous precipitation is controlled by the grain boundary diffusion.(3)Cu-3ti and Cu-3ti-0.5cr alloys were prepared by vacuum melting.The two alloys were rolled at 50%,70% and 90% deformation respectively at room temperature.The aging treatment was carried out at 450 ? for 0-12 h.It was found that the addition of Cr slowed down the process of amplitude modulation decomposition and discontinuous precipitation of Cu-3ti alloy,and the precipitated phases of Ti Cr were formed on the grain boundary.(4)It is found that the addition of Cr increases the peak hardness of the alloy most obviously at 90% rolling deformation.In addition,under the condition of 450 ? and 90% rolling deformation Aging for 12 hours,the decrease of conductivity caused by Cr addition is the smallest,only 1.2% IACS.Therefore,the comprehensive properties of the alloy obtained by aging at 450 ? and rolling at 90% are the best.(5)The volume fraction of Cu-3ti and Cu-3Ti-0.5Cr discontinuous precipitation in rolling aging state was calculated.It is found that the addition of Cr can reduce the volume fraction of discontinuous precipitation after full aging,but accelerate the discontinuous precipitation in the early and middle stages of aging process. |
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