Properties of Potassium Doped and Tantalum Containing Tungsten after Heavy Ion Irradiation

Tungsten potassium (WK) alloy has been reported as one of the ideal plasma-facing materials (PFMs). Tantalum alloying is a good method to improve the mechanical properties of tungsten. The effect of tantalum contents on the irradiation resistance of WK alloy has not yet been reported. In this study, WK (containing 82 ppm potassium) alloy with 1 wt. % Ta and 3 wt. % Ta, specifically WK-1Ta and WK-3Ta, were fabricated with sparking plasma sintering and irradiated with 7.5 MeV W2+ ion. The relative densities of WK-1Ta and WK-3Ta are 97.2% and 96.4%, respectively. The average grain sizes of WK-1Ta and WK-3Ta are 2.08 & mu;m and 1.51 & mu;m, respectively. The Vickers hardness of WK-3Ta is nearly 20% higher than that of WK-1Ta, both before and after irradiation. Irradiation hardening was confirmed by nano indentation test results. After irradiation, the number of dislocation loops formed in WK-1Ta and WK-3Ta are very similar, and the dislocation loop density of WK-3Ta is only slightly higher than that of WK-1Ta. This phenomenon is consistent with nano hardness analysis results. Compared to the reported nano hardness results of WK alloys, both WK-1Ta and WK-3Ta had higher hardness than the WK alloys before irradiation. Compared to the irradiation hardening results for the reported WK alloys, the existence of Ta may have positive influence on resistance to irradiation hardening.