Surface cracking of tungsten-vanadium alloys under transient heat loads

• Transient thermal shock stability of W-V alloys.
• The alloys with lowest V concentration are highly damaged in terms of high crack density.
• The alloy with intermediate V content (5 wt%) shows better cracking resistance against transient heat loads.
• Peak surface temperatures of all samples at all tested power densities are well below melting point.
• W-V alloy of high V concentration, has better mechanical strength but undergo much higher surface temperature during heat loading.

To evaluate high heat load performance of tungsten-vanadium (W-V) alloys as a potential candidate for plasma facing materials of fusion devices, the target materials with three different V concentrations (1, 5 and 10 wt%) are exposed to thermal shock loading. The alloys are fabricated by cold isostatic pressing and subsequently sintered in a vacuum furnace. Thereafter, they are exposed to different high heat flux densities ranging from 340 to 675 MW/m2 for single shot of 5 ms duration in an intense electron beam test facility. The alloys with lowest V concentration (1 wt%) are highly damaged in form of seriously cracking. The ones with intermediate V content (5 wt%) has shown comparatively better performance than both highest and lowest V contents alloys. The results indicate that improved mechanical properties and reduced thermal conductivity due to V addition comprehensively affect the cracking behavior of W-V alloy under transient thermal shock.