Microstructure of electrodeposited tungsten coatings after 30 keV helium ion implantation

Abstract

Compact and smooth tungsten coatings on nuclear grade graphite (IG-430) substrate were successfully prepared by an electrodeposition method from Na2WO4 - WO3 molten salt. The average grain size and the thickness of the prepared coating was about 20.34 μm and 120 μm, respectively. In addition, the electrodeposited tungsten coatings were subjected to ion implantation with 30 keV helium (He) ions to different fluences to evaluate their irradiation resistances. The microstructure evolution of the electrodeposited tungsten coatings was investigated. The results show that all samples suffered surface blistering after ion implantation, and the tungsten coating surface suffered more morphology changes with the increase of ion fluences. Serious blistering, ripple-like structure and grain boundary separation were formed on the coating surfaces after implantation of the highest He fluence of 1 × 1018 cm−2. Moreover, the levels of grain damage were dependent on the tungsten grain orientations. The levels of damage on tungsten grains with low index orientations increased in the order of (100), (110), and (111).