High temperature tensile properties and their application to toughness enhancement in ultra-fine grained W-(0-1.5)wt% TiC

Ultra-fine grained (UFG) W-TiC consolidates are very promising for use as divertors in fusion reactors, however, the assurance of room-temperature ductility of UFG W-TiC remains unsettled. The assurance requires a sufficient degree of plastic working for the consolidates and thus overcoming of poor plastic workability in UFG W-TiC by applying superplasticity. Therefore, the magnitudes of elongation to fracture and flow stress which are important measures for plastic working were examined for UFG W-(0–1.5)%TiC (in wt%) at 1673–1973 K where superplasticity occurs without appreciable grain growth. It is shown that the elongation and flow stress are strongly dependent on TiC addition and atmosphere (Ar, H2) during mechanical alloying (MA). As the TiC addition increases, the elongation significantly increases without appreciable increase in the flow stress level. W-TiC fabricated with MA in H2 exhibits larger elongation and larger strain rate sensitivity of flow stress than W-TiC with MA in Ar. These results were applied to perform plastic working and the room-temperature bend test results for plastic worked W-1.0%TiC are shown.