Research On The Microstructure,properties And Densification Process Of SiCp/6061Al Composites Prepared By Hot-press Sintering

In order to investigate the effects of process parameters on the densification process of Si Cp/6061 Al composites in depth,in this paper,Si Cp/6061 Al composites with a volume fraction of 10% were prepared from micron-sized 6061 Al and Si C particles using vacuum hot-press sintering technique.The effects of these three process parameters on the densification process were also analysed based on the effects of sintering temperature(430°C～510°C),sintering pressure(15-30 MPa)and holding time.Meanwhile,two-dimensional and three-dimensional hot-pressing models were developed using the multi-particle finite element method to simulate the hot-pressing process of 6061 Al powder and Si Cp/6061 Al composite powder with 10% volume fraction at different sintering temperatures(430°C～510°C)and sintering pressures(15～30 MPa).The densification process was investigated from two perspectives:macroscopic densification changes and microscopic particle displacement and deformation.Finally,the reliability of the finite element simulation results was verified from both theoretically and experimentally,and the influence of the process parameters on the powder densification process is summarised.The experimental results show that the Si Cp/6061 Al composites prepared at a sintering temperature of 490°C,a sintering pressure of 25 MPa and a holding time of 1h have the best homogeneity,the highest densities and the best mechanical properties.The reinforcement particles smashed in the ball milling process and the sharp corners ground down formed small size reinforcement particles distributed around the matrix particles,which made the bond between the matrix and the substrate stronger and the tensile strength of the composite increased significantly.The simulation results show that the maximum value of the densities increases gradually with the increase of pressing temperature and pressing pressure.The maximum growth rate of the final density was found in the range of 470℃～490℃ and20～25 Mpa for the pressing temperature and pressure respectively.The Si Cp/6061 Al composite powder has better particle rearrangement due to the small and medium size Si C compared to the pure 6061 Al powder particles of the same size.Compared with the3 D model,the 2D model has a slightly lower particle rearrangement effect,and the calculation is more efficient.The combination of experiments and simulations demonstrates that different process parameters influence the different stages of densification.Increasing the sintering temperature results in a more plastic deformation and flow capacity of the material,which also increases the densification.Increasing the pressure results in more adequate particle rearrangement and greater plastic deformation,which also contributes to the increase in densification.Increasing the sintering temperature,increasing the sintering pressure and extending the holding time all increase the diffusion distance between the particles,where increasing the temperature increases the diffusion coefficient and diffusion activation energy,increasing the pressure allows the particles to bind more tightly and extending the holding time changes the duration of diffusion,all of which make the diffusion more adequate.51 pictures,5 tables,96 references.