Irradiation in BCC materials: Defect-induced changes of the effective dislocation mobility and their relation with the dose-dependent fracture response

Abstract : The mechanical response of nuclear structural materials and their lifetime are strongly affected by radiation effects. This influence is of concern, especially in body centered cubic (BCC) materials, which exhibiting a well-defined ductile to brittle transition. The ductile to brittle transition temperature (DBTT) itself is dose-dependent and may rise to or above the room temperature. In current work, the irradiation effect is modeled to predict the dose-dependent changes of the effective dislocation mobility, represented by the Defect Induced Apparent Temperature Shift (DDIAT). Mainly dislocation based crystal plasticity material model is used rather than a phenomenological approach. This material model accounts for both thermally activated dislocation mobility and dislocation mobility in an athermal regime of BCC materials. The defect-induced evolution of DDIAT in turn analyzed and their relations with the fracture response are highlighted and discussed.