Morphological and nanomechanical alteration of tungsten in extreme environments, like those in edge localized modes in nuclear fusion environments, up to 46.3 GWm−2 heat fluxes were experimentally simulated using electrothermal plasma. Surface and subsurface damage to the tungsten is seen mainly in the form of pore formation, cracks, and resolidified melt instabilities. Mirco voids, rosette-type microfeatures, core-shell structure, particle enrichment, and submicron channels all manifest in the damaged subsurface. The formation of voids in the subsurface was determined to originate from the ductile fracture of hot tungsten by plastic flow but not developed to cracking. The voids were preferentially settled in grain boundaries, interfaces. The directionality of elongated voids and grains is biased to the heat flow vector or plasma pathway, which is the likely consequence of the thermally driven grain growth and sliding in the high-temperature conditions. The presence of a border between the transient layer and heat-affected zone is observed and attributed to plasma shock and thermal spallation of fractural tungsten at high temperature. Plasma peening-like hardening effects in tungsten were observed in the range of 22.7–46.3 GWm−2 but least in the case of the lowest heat flux, 12.5 GWm−2.

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Tungsten and tungsten carbide were exposed to high heat flux (29.8-59.6GW/m2) using a femtosecond laser with different incident angles (0°, 30°, 45°, 60°). The total heat flux was accumulated through laser pulses in ambient air. The aim of these experiments was to simulate the high heat flux conditions and oxidation to show the surface damage and ablation in harsh environments. At 1–8 laser pulses numbers, the tungsten surface was more durable than tungsten carbide, but at very high pulse numbers (~ 5,200) the opposite was true. Due to laser induced plasma formation, the surface damage mostly took the form of craters that were near-circular at low impact angles and more elongated at higher angles. A cluster of tungsten oxide debris also formed on the tungsten surfaces. Laser Induced Periodic Surface Structures (LIPSS) and grooves were formed during laser exposure, and their geometries vary with laser intensity and with laser impact angle. The period of laser induced surface changes increased for both tungsten and tungsten carbide surfaces as the incident angle increased. More mass was lost in from tungsten than tungsten carbide, which agrees on the morphological responses. The mass loss by laser ablation overwhelmed the possible mass gains from surface oxidation.