Study On Ablation Of Materials Irradiated By High-Intensity Pulsed Ion Beam

The experimental investigation of ablation on metallic materials, graphite and oxide coatings irradiated by high-intensity pulsed ion beam (HIPIB) were performed in TEMP-6 HIPIB apparatus with the ion energy of 300 keV, the pulse width of 70-80 ns, the ion current density of 60-500 A/cm~2 and the energy density of 1-12 J/cm~2 and ETIGO-II apparatus with 1 MeV, 50-60 ns, 1500 A/cm~2 and -90 J/cm~2, respectively. The changes in their surface morphologies and phase structures were investigated, combining the theoretical modeling of surface ablation process, in order to explore the interaction mechanism between HIPIB and materials. Based on the ablation effects of HIPIB irradiation on materials surface, the applications of HIPIB are possibly extended in the surface modification of materials.As revealed by the experimentals on metal Ti by HIPIB at 100-200 A/cm~2 up to 5 shots and at 1500 A/cm~2 up to 3 shots, the micro non-uniformity of geometrical factors on the irradiated surface, e.g. micro-protrusions and caves etc., induced a selective melt and ablation, which caused the ablated surface morphology with a primary feature of cater formation at 100 A/cm~2 by droplet ejection and waviness formation at 200 A/cm~2. As the ion current density increased up to 1500 A/cm~2, a flat surface on the center of ion beam caused by uniform ablation and the morphologies with a feature of coexistence of waviness and craters adjacent to the center were observed. As increasing shot number from 1 to 5 at 200 A/cm~2, the surface morphology of irradiated Ti samples became smoother and more uniform. However, the phase structure on these irradiated Ti surfaces was unchanged, being a single a-Ti phase. The irradiation of intermetalics γ-TiAl by HIPIB was performed at 60-200 A/cm~2 up to 50 shots and at 50-90 J/cm~2 with 1 shot. The surface underwent the heterogeneous thermal effects, i.e. the selective heating, melting and ablating, due to the existence of element with low melting point and grain boundary. The heterogeneous thermal effects led to an ablated surface morphology with a feature of coexistence of waviness and craters, as well as serious cracking on the surfaces of γ-TiAl along the grain boundaries. A selective ablation of Al element was confirmed by the fact that new phases...