Preparation And Hot Deformation Behavior Research Of Wc-Al₂O₃/Cu Composites

Resistance welding is widely used in many areas of modern industry, the electrodeworks in a typical thermal-mechanical coupling condition. Resistance weldingelectrode material should have good high temperature performance, high strength, goodthermal and electrical conductivity properties, and high softening temperature. Thiswork uses the powder metallurgy method to prepare the WC-Al₂O₃/Cu composites.Main processes:（1） mixing powder according to the proportion with low energy;（2）preparation of composite powder by high energy ball milling process, and study theinfluence of the milling time in microstructure and properties of the composite powder;（3） preparation WC-Al₂O₃/Cu composites with a certain density by pressing at roomtemperature and sintering process in the vacuum, then conduct the research on thevariation of the density with pressure;（4） dense the sintered WC-Al₂O₃/Cu compositeby plastic deformation, including hot extrusion and rolling process, and study theinfluence of different process on the microstructure and properties of compositematerials. The test of the composite powder which obtained after different milling timeand its block shows that the milling time has a very important effect on microstructureand mechanical properties of composite powder.This work studies mechanical properties, thermal properties, electricalconductivity and softening temperature of5wt%WC-2wt%Al₂O₃/Cu composites and10wt%WC-2wt%Al₂O₃/Cu composite. The tensile test and hardness test show that thetensile strength of two kinds WC-Al₂O₃/Cu composite with different components,5wt%WC-2wt%Al₂O₃/Cu composite and10wt%WC-2wt%Al₂O₃/Cu composite, are234.25MPa and244.54MPa, and for hardness,147.5HB and150.5HB, respectively;then the thermal performance tests show that the coefficient of thermal expansion oftwo kinds composites are10.14×10-6/K and9.87×10-6/K, and for thermal conductivity,338.250Wm-1K-1and321.163Wm-1K-1,respectively; two kinds WC-Al₂O₃/Cucomposites’ electrical conductivity are85.28%IACS and77.41%IACS, and thesoftening temperature of the two kinds of the composite are both higher than900℃.Compare the main properties of5wt%WC-2wt%Al₂O₃/Cu composite and10wt%WC-2wt%Al₂O₃/Cu composite with resistance welding electrode material in thenational standards and find that the properties of two kinds WC-Al₂O₃/Cu compositesare higher than the national standards, therefore, this material is likely to be a new typeof resistance welding electrode material.This work studies the hot deformation behavior of10wt%WC-2wt%Al₂O₃/Cucomposite by thermal compression tests, and analyses the relationship of the flow stress and deformation temperature, strain rate. Then draws the hot processing map of theWC-Al₂O₃/Cu composite material under certain temperature and strain rate which isbased on the dynamic material model （DMM）, to provide guidance and basis for theplastic processing of this material.