Fabricated And Investigation On Microstructure Properties Of Novel TiC_0.5-Al₂O₃/Cu Composites

TiC/Cu matrix composites have been widely studied and applied in some specific fields,such as electromagnetic gun guide material,electrified railway overhead wire and auto automatic welding electrode,etc.These application fields have put forward more severe tests on its electrical conductivity,thermal conductivity,mechanical properties and friction and wear properties.However,due to the poor wettability between TiC and Cu,the interface bonding is not strong and the mechanical properties do not meet the requirements.In addition,the electrical conductivity of TiC/Cu matrix composites is also low.In order to make TiC/Cu matrix composites more suitable for these applications,it is necessary to improve the wettability between TiC and Cu matrix and enhance the electrical conductivity of the materials.In this paper,TiC_0.5-Al₂O₃/Cu matrix composites were prepared by SPS sintering with Ti₂Al C and Cu₂O/Cu as starting materials.The reaction mechanism,the effect of preparation process on the material properties,the cold deformation behavior and the friction and wear properties of the materials were studied.The results are as follows:(1)Ti₂AlC-Cu₂O/Cu system has started to react at 900?,and the reaction is completed at 980?.Ti₂Al C particles were completely decompose into submicron TiC_0.5 particles at 980?.Al atoms diffused from Ti₂Al C into Cu matrix and then reacted with Cu₂O to form Al₂O₃ grains.(2)With the increase of sintering temperature,the relative density and conductivity of the materials firstly decreased and then increased,while Vickers hardness and yield strength first increased and then decreased and reached the maximum value at 980?.The properties of the materials prepared at different sintering temperatures were compared.When the sintering temperature was 980?,the comprehensive properties of the materials were the best.With the addition of(Ti₂Al C+Cu₂O)increasing,the electrical conductivity of the material decreases gradually,the Vickers hardness and compressive yield strength of the material increase.The properties of the materials prepared with different Ti₂Al C supplemental amounts were compared.When the Ti₂Al C supplemental mass fraction was 3%,the comprehensive properties of the materials were the best.With the increase of ball milling time,the electrical conductivity of the composite materials decreases firstly and then increases,while the Vickers hardness and yield strength increase firstly and then decrease.The properties of the materials prepared by adding Ti₂Al C with different original particle sizes were compared.When the original Ti₂Al C ball milling time was 8 h,the comprehensive properties of the materials were the best.In summary,the optimal preparation process as follows:the mass fraction of Ti₂Al C is 3%,ball milling time is 8 h and sintering temperature is 980?.(3)With the increase of cold rolling deformation,fibrous microstructure began to appear.The TiC_0.5 particles distributed in the matrix were broken into fine particles and distributed in a streamlined manner.When the cold rolling deformation was 50%,the fibrous microstructure distribution was very uniform,and the aspect ratio of TiC_0.5particles was large.The Vickers hardness of the material increases with the increase of cold rolling deformation,but the conductivity of the material changes little.The elongation of the material decreases from 12.5%to 10.52%,and the elongation remains above 10%,which indicates that the material can also maintain good plasticity after cold rolling.The fracture morphology analysis shows that there are a lot of dimples and shear ridges in the fracture,which indicates that severe plastic deformation has been carried out during the tensile process.In addition,with the increase of cold deformation,bremsstrahlung becomes shallow and more.The wear mechanism of the material is adhesive wear plus abrasive wear.With the increase of the cold rolling deformation,the friction coefficient of the material decreases,and the width of the wear mark also decreases accordingly,which indicates that the cold plastic deformation can improve the friction and wear properties of the material to some extent.Meanwhile,it can be observed from the wear mark morphology that the friction mechanism changes,and the abrasive wear mechanism plays a major role.