Research On The Microstructure And Performance Of TiC_0.5-Al₂O₃/Cu Composites Prepared Base On In-situ Dissociation Of Ti₂AlC

Copper matrix composites play an important role in the development of human society.With the rapid development of modern industry,many higher and newer requirements are put forward for the performance of copper matrix composites.The Cu-Ti C composites are widely used in electronics and electricians,transportation,aerospace and other fields because of their good electrical and thermal conductivity,high strength and hardness,and good wear resistance.However,the poor wettability and weak interfacial bonding strength between Ti C particles and Cu matrix greatly limit the performance improvement of the composites.Ternary layered ceramic Ti₂Al C phase has excellent properties of both metal and ceramic.In structure,Al atoms are weakly bonded with other two kinds of atoms,which are easy to break at high temperature and Al atoms are easy to diffuse out.In this paper,Ti C_0.5/Cu（Al）composites were prepared by using pure Cu powder and Ti₂Al C powder with a mass fraction of 1%by high-energy ball milling and spark plasma sintering.On this basis,Ti C_0.5-Al₂O₃/Cu composites were prepared by adding Cu₂O powder as an oxygen source.The effects of sintering temperature,ratio of ball to powder and ball milling time on the microstructure and properties of Ti C_0.5/Cu（Al）composites,and the effects of primary and secondary ball milling on the microstructure and properties of Ti C_0.5-Al₂O₃/Cu composites were studied.Both materials were cold rolled with70%deformation.The microstructure of the composites was characterized by metallographic microscope,field emission scanning electron microscope and field emission transmission electron microscope.The relative density,hardness,electrical conductivity and tensile properties of the composites were tested by Vickers hardness tester,electric conductivity tester and universal electronic testing machine.（1）Cu-1 wt.%Ti₂Al C powders were sintered at different temperatures.It was found that Ti₂Al C was decomposed into Ti C_0.5 particles completely at 900℃,and Al atoms were separated from the initial position into Cu matrix to form Cu（Al）solid solution.The Ti C_0.5/Cu（Al）composites were successfully prepared.With the increase of the ratio of ball to powder and ball milling time,the finer effect of Ti C_0.5 particles on the matrix is better,but the density of sintered materials is worse.When the ball milling speed is 220 r/min,the ratio of ball to powder is 10:1,and ball milling time is 6 h,the sintered materials tend to be completely dense and have the best comprehensive properties,and the electrical conductivity is 77.9%IACS.The microhardness is 111 HV,the tensile strength is 349.4 MPa and the elongation is 18.8%.（2）The interfacial reaction between Cu₂O and Ti₂Al C shows that at 900℃,the width of the interfacial reaction zone exceeds 270μm,the Al atom in Ti₂Al C dissociates from its initial position and grabs O in Cu₂O to form Al₂O₃ particles,and Cu₂O is reduced to Cu.（3）The Cu powder,Cu₂O powder and Ti₂Al C powder were used to prepare mixed powder by primary ball milling and secondary ball milling respectively,and then Ti C_0.5-Al₂O₃/Cu composite material was successfully prepared by SPS sintering at 900℃.Compared with The Ti C_0.5/Cu（Al）composite material prepared by the same process,Ti C_0.5-Al₂O₃/Cu composites have higher electrical conductivity.At the same time,it is found that the density of the composite prepared by secondary ball milling is higher,and the size of the complex particles of Ti C_0.5 and Al₂O₃ in the matrix is smaller.With the increase of the primary ball milling time,the comprehensive properties of the composite are also improved.When the primary ball milling time is 9 h,the electrical conductivity of Ti C_0.5-Al₂O₃/Cu composite is 83.2%IACS,the microhardness is 107.0 HV,and the tensile strength and elongation are 312.9 MPa and41.5%,respectively.（4）After 70%cold rolling,the microhardness of Ti C_0.5/Cu（Al）composite was increased from 111 HV to 137 HV,the tensile strength was increased from 349.4 MPa to 439 MPa,and the elongation decreased from 18.8%to 12.9%.The microhardness of Ti C_0.5-Al₂O₃/Cu composite increased from 107.0 HV to 132.7 HV,the tensile strength increased from 312.9 MPa to 452.0 MPa,and the elongation decreased from 41.5%to 11.3%.