Simulation Study On Deformation Behavior Of Copper-based Powder In Hot-pressing Process

The deformation of particles in the process of copper-based powder compaction is the main factor for the increase of density.It is very important to study the deformation behavior of particles in densification process to improve the density and properties of alloy products.Based on the discrete body finite element method,The densification behavior of particles in the two-dimensional idealized arrangement(square and hexagonal arrangement)of pure Cu and Cu-W particles is investigated using MSC/Marc finite element analysis software on the optimization of the particle finite element model,At the same time,the influence law of pressing process(pressing force,interparticle friction,temperature)on the forming density and grain strain is studied.The results have important reference value for improving the density and properties of copper-based alloys.The article results are as follows:(1)Using MSC/Marc finite element software,a finite element model of the twodimensional ideal arrangement(square and hexagonal arrangement)of pure Cu and Cu-W particles is established.the flow of the compacts during the compaction process and particle position displacements at different positions.of the two powders are studied.The results show that a whole downward flow during the pressing process.The displacement of the uppermost row of particles is the largest and decreases in descending order.The displacement of the joints in the same particle at different positions mainly occurs in the Y direction and the dot of the maximum displacement occurs at the initial point of contact between the particles.(2)The deformation characteristics of typical particles and the densification of green compacts during the press forming process of pure Cu and Cu-W heterogeneous powders are analyzed.The results show that the Cu particles deformation in pureCu-pressed starts from the initial contact point of the particles along the axial direction toward the center of the particle and on both sides,Eventually the Cu particles will become square and hexagonal in two regular shapes.In the Cu-W heterogeneous pressing process,the Cu particles become concave arcs on the outer surface in contact with the W particles.At the end of pressing,there is still a certain gap between the square array particles,and the gap between the hexagonal array particles has been basically filled.(3)The magnitudes of strain of copper particles in different directions during the compaction process of pure Cu and Cu-W foreign powders are analyzed,and the strain of Cu particles from surface to interior during Cu-W hetero-compression is analyzed.The results show that the main strain range of the square-arranged Cu particles is in the range of 30° to 150°C and the strain range of the hexagonal Cu particles is roughly a “W” distribution,and the maximum strain values of pure copper are respectively 0.45 and 0.41.The maximum strain values of the Cu-W heterogeneous presses are respectively 1.0 and 0.85.The strain value at the location node of the outer surface of the particle is not necessarily the largest along the central direction,it is related to the shape of the deformation of the particle and the location of the node.(4)The effects of pressing force,interparticle friction,and temperature on the forming relative density are studied.The results show that the maximum relative densities achieved by the square arrangement and the hexagonal arrangement are respectively 0.960 and 0.996,regardless of homogeneity or heterogeneous compaction.The increase of temperature can affect the plastic strain process of copper particles and soften the particles,which reduces the pressing force needed for forming.The internal friction of the particles only affects the hexagonal Cu-W heterogeneous pressing process,When the friction coefficient is between 0 and 0.2,the relative density changes up to 0.7%;When the friction coefficient is greater than 0.2,the relative density changes up to 0.2%.