Defect structures in metals exposed to irradiation of different nature

Abstract

The regularities of the defect structure formation in near-surface layers of metals and alloys under irradiation of different types are presented. Three types of irradiation were used to treat the targets: high-dose ion implantation (HDII), high-power ion beam (HPIB) and high-power pulsed microwave (HPPM). In the case of HDII the continuous and repetitively-pulsed regimes were used. Different ions (B, C, Ar, Fe, Ni, Hf, Cu, Mo, Pb, Zr, La, W, Dy) of 40–200 keV energy were implanted to the irradiation dose of 1 × 10 16 to 1 × 10 18 ion cm −2 in α-Fe, Cu and Mo metals and Ni 3Fe, Cu-Co-Al and VT18U alloys. Two-component pulsed HPIB (50% C + 50% H) was used to treat α-Fe. The energy of ions was 300 and 400 keV, the ion current density was 60, 100 and 200 A cm −2 and the pulse duration was about 100ns. Cu, α-Fe, Ni and Mo metals were exposed to HPPM with wavelengths of 2.85 and 10.0 cm. The microwave power flux density was varied from 2 to 400 kW cm −2, whereas the pulse duration was varied from 50 to 300 ns. The exposure to HDII, HPIB or HPPM irradiation leads to the generation of dislocations in the near-surface layer of metallic materials. The thickness of the near-surface layer with induced dislocation structure depends on the type of irradiation and is equal to several micrometres for HPPM, tens of micrometres for HDII and hundreds of micrometres for HPIB. The defect structures induced by irradiations mentioned above are similar to the defect structures formed in metals and alloys during plastic deformation at one-axis tension or compression. The main reason for defect structure formation in the metals exposed to irradiation is the high level of stresses originating in the target near-surface layer. The mechanisms of stress origination, the value and the nature of the stresses are determined by the type of irradiation.