Preparation And Properties Of High Softening Temperature Cu-WC Composites

The rapid development of new technologies such as 5G heat pipes and integrated circuits has put forward higher standards for the comprehensive properties of highperformance copper-based materials such as heat dissipation,mechanical properties at high service temperatures,and electrical conductivity.In this paper,a small amount of ultra-fine WC particles are dispersed in the copper powder particles by mechanical alloying process,and uniform and refined WC/Cu composite powder is prepared;Then a part of the composite powder is cold-pressed before sintered in two atmospheres(Hydrogen,vacuum),the other part of the composite powder was directly subjected to vacuum hot pressing sintering;Through the observation and analysis of XRD,SEM and TEM microstructure of the samples at different sintering temperatures,the properties such as density,strength,hardness,electrical conductivity,softening resistance and other properties of the samples were characterized;Finally,the optimal sintering process was determined and the strengthening mechanism of copper matrix composites strengthened by dislocation packing effect under the Orowan mechanism was analyzed.The main conclusions obtained are as follows:(1)1 wt.%WC/Cu and 2 wt.%WC/Cu-based sintered blocks were prepared by mechanical ball milling,cold pressing and sintering in two atmospheres of hydrogen and vacuum.The effect of green compaction on the density of sintered samples was studied,and the optimal pressing pressure of the composite material was determined to be 200 MPa.The temperature parameters were adjusted on the basis of the optimal pressing pressure,and the properties of the WC/Cu matrix composites,such as density,electrical conductivity and Vickers hardness,were studied at different sintering temperatures.Finally,the optimum hydrogen sintering temperature of the composite material is 1112 ℃,and the optimum vacuum sintering temperature is 1087 ℃.(2)Through mechanical alloying combined with vacuum hot pressing sintering,ultrafine WC particles uniformly dispersed Cu-based composite blocks were prepared at 1050 ℃ hot pressing sintering,and the relative density even reached full density.In addition,with the increase of hot-pressing sintering temperature,the change values of electrical conductivity and thermal conductivity are in a certain synchronization with the change value of relative density.(3)The 1 wt.%WC/Cu and 2 wt.%WC/Cu samples,successfully prepared by hot pressing sintering and hot rolling at 1050 ℃,not only have excellent tensile strength(406.72 MPa,405.12 MPa)and high hardness(126.6 HV,124.1 HV),but also have high electrical conductivity(99.1% IACS)and high softening temperature(850 ℃,900 ℃).In addition,the strengthening mechanism of ultrafine WC/Cu matrix composites is mainly due to the dislocation clogging effect in the Orowan mechanism to strengthen the composites,and the tensile properties of the composites after hot rolling are more determined by the interfacial strength of the reinforcement/matrix,and the substantial increase in the high softening temperature originates from the inhibition mechanism of WC particles on dislocation recovery and recrystallization.