Recrystallization behaviour of high-flux hydrogen plasma exposed tungsten

V Shah,J.T.S Beune,Y Li,Th Loewenhoff,M Wirtz,T.W Morgan,J.A.W Van Dommelen

doi:10.1016/j.jnucmat.2020.152748

Abstract

Knowledge of a material’s thermal stability under extreme synergistic particle and heat loads is crucial for developing high performance reactor materials. In this work, the recrystallization behaviour of tungsten under the influence of hydrogen is investigated by low energy high flux hydrogen plasma exposure for various lengths of time. The microstructural changes following exposure are probed by micro-indentation, electron back-scatter diffraction measurements and the characteristic time for recrystallization is assessed using the Johnson–Mehl–Avrami–Kolmogorov (JMAK) model. A recrystallization activation energy in the range of 425 to 440 kJ.mol-1 is determined, identical to that of oven annealed samples, thereby indicating an insignificant influence of hydrogen plasma on the recrystallization kinetics of tungsten.

Highlights

Over the past decade, the refractory metal Tungsten (W) has been identified as the leading candidate material for the plasma facing components (PFCs) for the divertor of future fusion reactors due to its favourable high temperature properties
The refractory metal Tungsten (W) has been identified as the leading candidate material for the plasma facing components (PFCs) for the divertor of future fusion reactors due to its favourable high temperature properties. The lifetime of these W PFCs is crucial for the efficiency, economics and good performance of the reactor as the divertor performs the vital function of extracting heat, helium and other impurities from the plasma [1,2]
Insights into the microstructural changes due to recrystallization were probed by performing microindentations, as recrystallization is characterized by a distinct reduction in hardness

Summary

Introduction

The refractory metal Tungsten (W) has been identified as the leading candidate material for the plasma facing components (PFCs) for the divertor of future fusion reactors due to its favourable high temperature properties. It should be noted that the picture is not fully complete, as there have been studies depicting an increase in the total elongation following recrystallization as compared to deformed state (similar testing temperature), implying a decrease in BDTT [11,14,15]. This is followed by a systematic post-mortem analysis to determine the recrystallization kinetics and compared with literature studies

Test samples

Magnum PSI: hydrogen plasma exposure

Post exposure characterization

Results and discussion

Conclusion

Declaration of Competing Interest