Structure-phase states of the metal surface and undersurface layers after the treatment by powerful ion beams

The structural phase state and strength properties of the surface layer and bulk were studied for metals and alloys with different melting temperatures exposed to high-power ion beams (HPIBs). It has been established that, irrespective of the ion beam specific power (Q ≈12-50 MW cm^-2) and in the absence of surface melting, a characteristic feature of the surface morphology is crater formation. The disclination and microtwin-type rotation defects, microcracks, the surface layer amorphization and dislocation substructures of different dislocation density were observed inside and in the vicinity of craters. It has been shown that changes in the element and phase states of the surface layer are due to vapor-plasma cloud deposition and adsorption of the gas medium of the accelerator working vacuum. A physical concept of the formation of high local gradients (moments) of stresses with their relaxation through disclination-type rotation effects under the HPIB action has been developed. A high-energy substructure with a high continuum disclination density was found experimentally. The evolution of the defect substructure was examined, depending on the distance from the surface under irradiation. Physical models of the crater formation and mechanisms for the formation of the dislocation-disclination substructures under the HPIB irradiation are proposed.