Abstract
Irradiation hardening regimes in metallic materials have been identified and characterized based on the mechanical property database for dozens of bcc, fcc, and hcp pure metals and alloys irradiated mostly at low temperatures (< ~200 oC). The semi-log plots of yield stress versus dose data display that the softening or pre-hardening regime is a common regime for the metallic materials, and therefore there exist at least four irradiation hardening regimes in the strength-dose curves: the pre-hardening, main hardening, saturation, and embrittlement regimes. The dose range of the pre-hardening regime increased with the strength of material, which indicates that strengthening materials by any means can delay or mitigate irradiation effects. In the majority of the metallic materials, the exponent of the power-law hardening function was about 0.5 in the main hardening regime and about 0.1 in the saturation regime. In these positive hardening regimes, the low strength pure metals such as Fe, Ta, Cu, and Zr displayed lower hardening exponents. It was found that the transition to the saturation regime occurred either by the plastic instability at yield or by the saturation of defect accumulation. For all materials analyzed, the doses to saturation in irradiation hardening were in the range of 0.003 � 0.08 dpa.