Characterization of dose dependent mechanical properties in helium implanted tungsten

In this work, we utilized spherical nanoindentation to investigate the mechanical property changes of helium (He) implanted tungsten (W) at different damage doses. According to the indentation stress-strain curve, two dose dependent phenomena were revealed: one is an increase in yield stress with increasing damage dose, and the other is enhanced softening following yield. Experimental measurements such as transmission electron microscopy (TEM) and positron annihilation spectroscopy (PAS) techniques, as well as molecular dynamics (MD) simulation were combined to explore the intrinsic mechanism of the dose dependent phenomena. This study proposed an efficient and promising way to measure the damage of the plasma facing materials and established an effective correlation between the mechanical property changes of He implanted W and its microstructure evolutions.