Nanostructuring of Cu-TiB ₂ induced by ion irradiation

The evolution of Cu-TiB ₂ alloys during irradiation with 1.8 MeV Kr ions was investigated. Room temperature irradiation led to the precipitation of ≈4 nm cubic-phase TiB precipitates, while irradiation at 650 °C led to the precipitation of ≈5 nm hexagonal-phase TiB ₂ precipitates. Precipitates were identified in irradiated thin films by electron microscopy, using diffraction patterns, chemical analysis, and high-angle annular dark field imaging. For elevated irradiation temperature, the size of these precipitates and their number density, ≈2-3 × 10 ²³ m ^-3, remained unchanged on increasing the dose from 1 × 10 ¹⁶ ions/cm ² to 3 × 10 ¹⁶ ions/cm ², indicating that the irradiation had led to the formation of a stable nanostructure. No extended defects such as dislocation loops were detected even at the highest dose, equivalent to 75 displacements per atom, suggesting that this type of nanostructuring can impart high radiation resistance.