Observing the Impact of Electric Current Percolation in Ti-6Al-4V Powders during FAST/SPS Processing with XCT Analysis

Abstract

A field assisted sintering technology (FAST) process at a range of temperatures under 20 MPa were interrupted at 0 s of dwell time to study early densification of Ti-6Al-4V samples. Powder compaction simulations were used for comparison to the early densification and quantitatively similar constructions observed to within 1.2% porosity variation. It was inferred from this validation, as well as XCT data that the increased necking in the axial direction was a feature of early densification due to the pulsed electric current percolation through the powder and resulting localised heating at particle-particle boundaries. Columnar features created by this are observed, and some qualitative visual analysis performed to quantify this necking angular development. Additionally, for these 0 dwell time samples, a process lag time was proposed, also seen in FEM simulations from previous work due to heat conduction time from the displacement of the optical pyrometer.