Surface morphology and microstructure evolution of trace titanium and yttrium in W-K-Mo-Ti-Y alloys under transient heat loads

Trace titanium and yttrium (~0.1 wt.%) were doped to the novel W-K-Mo-Ti-Y alloys to investigate their performance under simulated transient heat loads in fusion reactor. The micro-structure, Vickers micro-hardness, cracks formation and surface roughness after transient heat loads were analyzed through X-ray diffraction analysis (XRD), Vickers Micro-hardness device, scanning electron microscopy (SEM) and three dimensional (3D) industrial optical microscope, respectively. It indicated that the transient heat loads would lead to surface cracking and roughening on the loaded surface, as well as a decrease on micro-hardness. Further, trace titanium and yttrium doping in the samples could largely mitigate surface roughening after transient heat loads. Both titanium and yttrium have significant influence on the surface cracking threshold and plastic deformation, indicating the improvement of transient heat loads resistance in this novel alloy.