Texture and structure evolution of tantalum powder samples during spark-plasma-sintering (SPS) and conventional hot-pressing

Spark-plasma-sintering (SPS) is a compaction method whereby pulsed current is applied using a similar setup as conventional hot pressing. SPS experiments of tantalum powder samples have been performed at different sintering temperatures between 1500 °C and 1900 °C applying a comparatively short sintering time of 1 min. The compacted samples have been characterised in respect of texture, density, Vickers hardness, and phase composition. All results were compared with data obtained from conventional hot pressed samples which were compacted between 1500 °C and 1700 °C for 60 min. The density of the SPS compacted samples reached 80-95% of the theoretical value depending on the sintering temperature. The corresponding Vickers hardness is increased. The obtained pole figures as identified by XRD measurements of the spark-plasma-sintered and conventional hot pressed samples indicate a pronounced fiber texture in [1 1 1] direction independent from the sintering method. The experiments show a rearrangement to a more isotropic texture with increasing sintering temperature.