Study on the Densification Mechanism of Ti-6Al-4V Powder during High Velocity Compaction Based on the Evolution of Microscale Pores

The high velocity compaction process of Ti-6Al-4V powder is simulated by using two-dimensional multi-particle finite element method. The morphological features of pores among particles are quantitatively characterized. The change laws regarding the morphology and area filling of various typical pores during the compaction process are analyzed in detail. The powder densification mechanism is studied from the aspect of the evolution of microscale pores. The simulation results show that when the compaction pressure is lower than a critical value（about 1 500 MPa）, pores are mainly filled by particle rearrangement and plastic deformation, so that the slope of the density-pressure curve is steep, and the green powder assembly is easily densified. Above that critical pressure,the slope of the density-pressure curve gradually decreases, and powder densification becomes difficult. Microscopically, at the stage of particle rearrangement and plastic deformation, there are many quadrilateral pores with large area-ratios