Preparation And Properties Of Fe-Cu Composites By Vacuum Hot-pressure And Liquid Phase Sintering

Fe-Cu composites can combine the electrical conductivity and thermal conductivity of copper with the high strength and wear resistance of steel,which has high research potential.The ratio of Fe and Cu added can make the composite's electrical conductivity and mechanical properties unable to be taken into account.The Fe-Cu composite material was designed and prepared to be composed of iron-based framework and copper-branched structure,the electrical conductivity and mechanical properties of material were balanced.In this paper,vacuum hot-pressed liquid-phase sintering method was used to prepare Fe-Cu composite materials.Cu and Fe-based pre-alloyed steel powders were mixed in a planetary ball mill.After sintering,the materials were sintered and formed,and the theoretical copper content was studied.The effect of different sintering processes on the microstructure and properties of the prepared material was observed.The surface morphology of the sintered material was observed using OM,and the best sintering process was determined.In order to further improve the conductivity of the material,the content of copper was adjusted to make the copper branch structure thicker,and the effect of the increase of copper content on the electrical conductivity and mechanical properties was studied.Heat treatment and strengthening of the materials with increased copper content were studied.The effects of heat treatment on the microstructure and mechanical properties of the materials were investigated.The microstructure after heat treatment were analyzed by XRD and TEM.In the end,the SEM was used to observe the surface of the material after tribological behavior with different copper content,before and after heat treatment and loading current.The tribological behavior of the material was systematically studied.The main findings are as follows:1.For Fe-Cu composites,the best process parameters for vacuum hot-pressed liquid-phase sintering were sintering temperature 1040^oC,sintering pressure 20MPa,sintering time25min,and vacuum degree of sintering maintained at 6×10^-3Pa,containing 28.6wt.%Cu.The Fe-Cu composite had tensile strength of 600MPa,elongation of 8.3%,and conductivity of 15%IACS.2.The composite material containing 50.0wt.%Cu prepared by the optimum sintering process can achieve 31%IACS conductivity,copper cross-sectional area of 453.66?m² and tensile strength of 457MPa.During the preparation of Fe-Cu composites,Fe₄Cu₃ phase was formed,and the composites containing 37.2wt.%Cu were strengthened and toughened.After quenching and tempering,the iron matrix was tempered sorbite,and the interface between Fe and Cu was good.The tensile strength was 588MPa and the conductivity was20%IACS.3.The microscopic morphology of the specimen after tribological behavior was analyzed.Under small load or small sliding speed,the material wear was a combination of abrasive wear and adhesive wear,and the wear mechanism was adhesion under large load or large sliding speed.Wear,and there was a crack.After the current was loaded,the tribological behavior of the material was mainly the adhesive wear.Under the large current,the surface of material was more likely to form cracks,and the copper branch structure was more easily softened to form the third body.