Surface patterns formation by ion irradiation of PAN based сarbon fibers

Surface patterns on PAN based сarbon fibers under 3 and 30 keV He+ and 30 keV Ar+ ions irradiation were experimentally studied. It has been found that the depth distributions ν(х) of the number of displacements per atom (dpa) have a strong effect on the surface patterns on PAN-based carbon fibers. For not steady state profiles ν(х), a ridge-like structure oriented along the fibers is formed on the surface. At sufficiently high irradiation fluences with a steady-state profile ν(х), a corrugated structure is formed with corrugations transverse to the fiber axis. The corrugation effect is explained by twinning during plastic deformation of fiber shell crystallites caused by radiation-induced dimensional changes and mechanical stresses. •Irradiation with 30 keV Ar+ leds to the formation of corrugations on the carbon fiber.•Irradiation with 30 keV He+ leds to the formation of ridges along the carbon fiber.•Depth profiles of dpa have a strong effect on the surface patterns on carbon fibers.•Twinning is an important factor in the relaxation of ion-induced stresses in fiber shell.